SOME EFFECTS OF CHROMATIC 1LTIJMJIIATIOF, ICTLECTAKCE, AFP PRODUCT ROTATION OK GOKTH'G EFFICIEECY OF CHERRIES AND TOMATOES By Blaine Frank Parker A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Agricultural Engineering Year 195^ ProQuest Number: 10008400 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10008400 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 06- 1346 ABSTRACT This work concerns the sorting efficiency of cherries and. tomatoes a 3 affected 'by the spectral distribution of the illuminant, the reflectance of the fruit and its defects, and the rotation of the fruit as it moves along on the sorting belt. The investigation of illumination was begun by running reflectance curves for the outside surface of cherries, tomatoes, and cherry defects. These curves were used as basic data for •calculating a number of possible spectral distributions of illumination which should enhance the perceptibility of defects on red ripe cherries. It was found theoretically possible to enhance the perceptibility of dark defects on cherries by selection of illuminant spectral distribution; by the same analysis perceptibility of under-color defects could be increased only slightly. An effort was made to produce a spectral distribution from commercially available illuminants and gelatine filters which would enhance the perceptibility of dark defects on cherries. Four illuminant- filter combinations (rose pink, magenta, purple, and red) which con­ siderably enhanced dark processing plants. defects on cherries were tested in cherry Red and rose pink were eliminated because some workers complained that these colors of illumination caused eye strain and headaches; magenta was eliminated mainly on the basis of workers* comments which favored the purple illumination. The purple Illumination, produced by incandescent filament lamps and the purple filter, was tested for six five-hour periods during which samples of cherries were taken from the sorting belt with the purple Illuminant and from, a compareion belt with the regular illuminant. The results of tests using purple illumination showed that the sorting efficiency was increased about 10 percent (statistically significant at the 95 percent confidence interval)* This represented an improve­ ment of approximately 50 percent over the regular illuminant used in the plant. The perceptibility of dark defects on red tomatoes may be enhanced by the same method as used for cherries. tomato processing plants. No tests were conducted in The problem of color grading tomatoes was discussed briefly. Reflectance curves were run for three common belt colors (white, tan, and black) used in cherry processing plants, and recommendations were made for belt reflectance based on the reflectance curves and the theory of adaptation of the eye. Rotation of cherries as they move along sorting belts was investi­ gated and two devices for rotation of cherries, a stationary rod and a friction-coated rotating rod, were developed and tested. The rotating rod was more efficient than the stationary rod when the belt was com­ pletely loaded with cherries* Rate of inspection, spreading cherries on the sorting belt, fluorescence of cherry defects, sorting cherries by transmitted light, and other factors which affect efficiency were discussed briefly. iciuuiLLDiFiKru'r rr’ r u author gratefully acknowledges the guidance, suggestions and he iiiWrcst of Irofessor I). F. Vieut under whoso direction the research was conducted. lie expresses appreciation to Dr. C. D. Hans e of the Physics department for his suggestions and contributions and to Professor A. W . Farrail for making avallab3c the necessary funds for conducting the research. Also, he expresses sincere appreciation to the following; Dr. D. B. Judd, Head, Colorimetry Unit, national Bureau of Standards and hr, I. Liraeroff of the national Bureau of Standards for their suggestions; Michigan State Highway Department for use of its spectrophotometer and Mr. Bruce W. Preston of the highway department for his suggestions on its operation; Mia W. G. Pracejus, Lamp Department General Electric Co. for providing data on spectral distribution of commercial lamps; Min M. I. Morse, DuPont Co. and Mr. J. 0. Thompson of the Pittsburgh Plate Co. for information on spectral•reflectance of paint; Mr, Abe Vander 17eole of the Dunkloy Co. ICalsmzoo, Michigan for suggestions and samples of cherry sorting belts; Paw Paw Canning Company, Paw Paw, Michigan, Lawrence Packing Company, Lawrence, Michigan, and Northport Cherry Factory, Northport, Michigan for their cooperation in the field tests; and to many others who contributed suggestions or materials for the project. The writer expresses his deep gratitude and special thanks to his wife, Peggy, for her untiring work in sorting the cherry samples and for typing the manuscript several times as well as the final draft. continued aid and encouragement has been of priceless value. Her VITA Blaine Frank Parker was b o m on June 12, 192^ in Gaston County, Forth Carolina and lived on a farm, until he was eighteen years old. In high school he was active in debating, 1+-H Club, F.F.A. and was president of hia senior class. He attended Brevard Junior College at Brevard, Forth Carolina two semesters and entered the Army Air Force in March, 19^3* The following three years were spent as an Aerial Gunnery Instructor with overseas duty in England. In April of 19^+6 he entered Virginia Polytechnic Institute and enrolled in Agricultural Engineering. He was active in the student branch of the American Society of Agricultural Engineers, serving as reporter and vice president; Alpha Zeta, serving as Chancellor; Omicron Delta Kappa; and Phi Kappa Phi. During the summer of 19^7 vorked as an Agricultural Engineering Aide on a hay curing project for the LAS.P.A. He worked one full year before graduation on a co-op training program with the Tennessee Valley Authority. In March 1950, after completing requirements for the B. S, degree, he studied Education and other courses of his choice at George Peabody College in Nashville, Tennessee. Beginning in September, 1950 he worked two years as instructor In the Agricultural Engineering Department at Virginia Polytechnic Institute. Requirements for the Masters degree in Agricultural Engineering were completed in September, 1952 and the thesis was published in Agricultural Engineering in October, 1953 under the title "Nomographs and Data for Determining Winter Ventilating Rates for Poultry Laying Houses". In Septmeber, 1952 he entered Michigan State College to work for the Ph. 1, degree in Agricultural Engineering; minor, Physics. He is a member of the National Physics Honorary Society, Sigma Pi Sigma. On June 20, 1953 he married Mary Margaret Isenberg of Morristown, Tennessee. He registered as a Professional Engineer in 1952 and is a member of the following professional organizations: American Society of Agricultural Engineers, National Society of Professional Engineers, and Virginia Society of Professional Engineers. TABLE OF CONTENTS Page INTRODUCTION............ 1 Scope .... Cherry Problem. ....... Types of defects ......... Illumination for sorting ...... Viewing entire cherry surface........... ... ....... Cherry production in Michigan...............,..... «... Tomato Problem, ..... h 5 5 6 8 DEFINITIONS............... Terminology Used for Measurable Quantities, "PhysiGs'J....... Terminology Used for Theoretical Calculations.of.Visual.... Phenomena "Psychophysics"........ Terminology Used for Reporting Visual Phenomena, "Psychology". C-enoral Terms .... OBJECTIVES 2 2 3 .......... 10 10 11 11 13 REVTEU OF LITERATURE......... lk Illumination for Sorting............... lk Product Rotation and Other Factors Affecting Sorting Efficiency,.... 18 PERCEPTIBILITY’ DIFFERENCE............. 21 ....... 22 The Visual Process Three-Receptor Theory of Color V i s i o n . 23 2k General adaptation. ..... Color constancy ..... 26 Local and lateral adaptation. ..... 29 The Brightness Receptor. ...... 30 Principles of Perceptibility Difference................. 3^ For maximum perceptibility of colordifferences.. 3^ For maximum perceptibility of lightnessdifferences.... 35 PERCEPTIBXLITY OF DEFECTIVE CHERRIES Spectral Reflectance Curves Color Contrast....... ...................... 37 ........ 37 38 TABLE OF CONTENTS Continued PERCEPTIBILITY OF DEFECTIVE CHERRIES (cont*a) Page Lightness Contrast .......... 39 Contrast ratio. ..... 39 Commercially available illuminants ................ k2 Theoretical filters........... ^9 Commercially available filter’s ....... 5& PEECEPTIBILITY OF DEFECTIVE TOMATOES............................ 6l COLOR GRADING TOMATOES 63 .............................. PRODUCT ROTATION................................................ 67 Preliminary Test Using Marbles....... Rotation of Cherries ......... Rotat Ing rod .... Stationary rods ...... Deflection Plates....... 67 68 69 72 7^ OTHER FACTORS IN SORTING EFFICIENCY, , .......................... 75 Rate of Inspection ........ Viewing the Entire Surface of Product...................... Sorting Cherries by Transmitted Light...... Fluorescence of Defective Cherries...,..,.......... Specular Gloss .............. CHROMATIC ILLUIE.'ATION TESTS HI CHERRY PROCESSING PLANTS....... Tests Tests Tests at Plant A .,........ at Plant P ......... at Plant C ...... FURTHER ANALYSIS OF CHERRY SORTING............................. 75 76 76 'Jo 79 80 82 87 91 93 Psychological Reactions to Chromatic Illumination,...... 98 Contrast Ratio and Illuminant Efficiency....................102 Brightness Adaptation....... 107 Reflectance of Background....... 108 SUMMARY AND CONCLUSIONS........................ HI Principles of Perceptibility Differences...... .... .111 For maximum perceptibility of color differences,.......111 For maximum perceptibility of lightnessdifferences.... 112 Illumination for Cherry Sorting. ..... *112 TABLE OF CONTENTS Continued Page SUMMARY AMD CONCLUSIONS (cont'd) Sorting Dark Defects from Red Tomatoes... ............ Color Grading Tomatoes ......... Viewing the Entire Surface of the Product........ Other Factors....... APPENDIX I 115 115 116 117 REFLECTANCE CURVES................................. 119 APPENDIX II FIELD TEST DATA APPENDIX III SPECTRAL DISTRIBUTION OF G. P. FLUORESCENT AMD TUNGSTEN FILAMENT LAMPS............. .APPENDED REFERENCES ........ OTHER REFERENCES.......... .................... 139 -Lk6 lk8 151 LIST OF TABLES Table Sage I System of Romenclature for Color Terms. II Contrast Ratios and Relative Luminous Flux Reflected from Cherries Illuminated by Fluorescent or Incandescent Lamps .................................... bR III Contrast Ratios and Relative Luminous Flux Reflected from Cherries Illuminated by G. L, Do Luxe Warm White Fluorescent Lamp ■withCommercial Filters ...... 60 Percent of Three-Quarter Inch Diameter Glass Marbles Rotated by Devices on..Sorting Belt.......... 68 Filters and Illumination for Tests Using Deluxe Warm White Fluorescent Lamp at Plant A . ...... 3L IF F ........ 9 FI Summary of Tests at Plant A Using Deluxe Warm. White Fluorescent Lamps and Filters as Indicated............. 86 FII Summary of Tests at Plant B Using 100 Watt Filament Type Incandescent Lamps and Filters as Indicated....... 90 Fill Summary of Tests at Plant C Using 1^0 Watt Filament Type Incandescent Lamps and Filter B-23 as Indicated... 9^ IX Contrast Ratios and Relative Luminous Flux Reflected from Cherries Illuminated by 2910° K Tungsten Lamp with Theoretical Filters ............... 10b X Contrast Ratios and Relative Luminous Flux Reflected from Cherries Illuminated by G. E. Deluxe Warm White Fluorescent Lamp with Theoretical Filters*.............10U XI Contrast Ratios and Relative Luminous Flux Reflected from Cherries Illuminated by Fluorescent or Incandescent Lamp with Commerical Filters *.... 100 Corrections for Wavelength Scale of Cenco-Sheard Spectrophotometer. ..... 121 XII XIII List of Samples and Defects Counted for Chromatic Illumination Tests at Plant A ...... XIF List of Samples and Defects Counted for Chromatic Illumination Tests at Plant B............... 1^0 LIST OF TABLES Table Continued La_c XV Lj.st of Samples and. Defects Counted for Chromatic Tllumination Testa at Plant C.......... ......... ...... XVI Spectral Distribution of G, E. Fluorescent and Turpstcn Filaraent Lamps....... ...... ., *......,................1^7 r- -? -A.X. t -rr'or. an iunrovorient in peivceptibility of defects will man© it -juaij ' W p r ;luc higher grades ; tnus, result 1113 ru m g r m 1 ch i cry p'.a , ■<. Tomato Problems Some pha.ses of the tomato problem are rather similar to the cherry problem; namely, the tomatoes should be viewed on al.l surfaces and the visual appearances of defects and the ripe fruit are rather similar. Potation of tomatoes may be accomplished by roller conveyors. In processing plants where sorting belts are employed the tomatoes are rotated to some extent by hand. Mechanical rotation is desirable, but It not as critical as rotation of cherries. Since tomato defects are usually larger than cherry defects, the perceptibility of defects is not as acute. In canning Michigan tomatoes it is desired to separate tomatoes into grades one, two, and culls. The number one tomatoes are red ripe and mellow; number W o tomatoes are firmer and slightly lighter in color. The culla for canning are medium ripe and rather hard. This task would require critical color judgement if appearance were the only criterion. Actually, the workers use firmness as well as appearance for grading * The plant operators visited did not seem to be aware of any particular grading difficulties in this operation; however, it is conceivable that a better grading job could be acheived if special illuminants were to improve the perceptibility of color grades. There is another color sorting problem for tomatoes which are shipped into the state during the winter months and marketed as they become ripe. These tomatoes are graded into four color grades (green, 7 light pin!:, pin!, and red). Also, defective tomatoes are removed. The green and pink tomatoes are placed in storage for ripening and the red tomatoes are delivered to market* are again color graded. At a later date the stored tomatoes It is desirable to store tomatoes which will ripen at approximately the same time in the same storage since this will reduce the amount of re-grading necessary. The problem arises from the fact that marginal color decisions between green, light pink, pink, and red are difficult to make, especially when it is required to make these decisions continously for several hours. It Is desired to determine the effect of the spectral distribution of illuminants on the perceptibility difference of the various color grades. DEFII1ITI0KC The terminology used in color descriptions are necessarily complicated. However, it is imperative that one knows whether the terms used represent measurable quantities in the physical sense, theoretical quantities which are based on agreed standards but cannot be measured directly, or the perception of radiant energy as reported by an observer. There is need to discuss light in all these relations. The committee on Colorimetry of the Optical Society of America has developed a system which is very helpful in establishing definite nomenclature (Table I). The first group of terms in Table I are listed under "physics". These are measurable quantities of radiant energy without reference to the eye. The next group of terms are listed as "psychophysics". These terms refer to values which may be calculated considering the eye as a standardized light receptor. The accepted standard for the eye is that designated since 1931 ly the Intemation (official abbreviation, CIE).* Commission 011 Illumination The last group of terms, which depend on the observer’s mental Interpretation of radiant energy, are grouped under "psychology" and depend on wavelength sensitivity of the eye, level of adaptation and psychological factors (observer experience, attitude, etc.). * ICI was used until 1951 when the Commission adopted the abbrevia­ tion of the French name, Commission Internationale de I ’Eclairage. TABLE I System of Nomenclature for Color Terms (U) Physics_______ Psychophysics Visual Stimulus Radiant energy Spectral Composition Light Psychology Visual Sensation Luminous energy Color Color sensation Characteristics of Radiant Energy Characteristics of Light = Color Attributes of Color Sensation Radiant flux Radiance Irradiance Radiant reflectance Radiant transmit tanc e Luminous flux Luminance Illuminance Luminous reflectance Luminous transmittance Brightness Spectral distribution Chromaticity (Relative spectre! . Dominant wave­ length (or composition, Complementary) Quality) Radiant purity Visual Perception Purity Corresponding • Modes of Appearance Aperture (1-5) Illuminant (1-8) Illumination (1-3) Object modes: Surface (l-ll) Volume (1-9) Chromaticness Attributes of modes of appearance: 1 .Brightness (or Hue lightness Saturation 2. 3. h. 9. 6. 7. 8. 9. LO. .1, Hue Saturation Size Shape Location Flicker Sparkle Transparency Glossiness Luster 10 Id order to obtain a more definite understanding of the meaning of the words used, the following list of definitions are presented. TerminoLogy Used for Measurable Quantities, "Physics” ^. Radiance---radiant energy from a source per unit time per unit solid angle per unit projected area of source. 2. Irradian.ce-— E, radiant energy incident on a surface per unit time per unit area. 3. Radiant Reflectance (reflectance) R, ratio of reflected to incident radiant energy. b. Spectral Distribution Curve a curve showing the relative radiant energy at various wavelengths in the electromagnetic spectrum. Terminology Used for Theoretical Calculations of Visual Phenomena, hPsychophysics^ 1. Luminosity Function L, relative spectral eensitivity of the eye considered as a standardized receptor, the CIE standard observer (see Figure 3)« 2. Luminancer ^ L ^ ) &X.*, the effective stimuli from a o light source. That is, evaluation of a light source as to its effective­ ness in producing visual sensation,evaluated in terms of the CUE standard 00 observer. 3. Luminous Reflectance— , the ratio of reflected to incident light evaluated in terms of the CIE standard observer when using a specified Illuminant. * The subscript, is used in color notation to indicate that the variable is a function of X. * Luminous Transmittance-- , the ratio of o transmitted, to incident light evaluated in terms of the CIE standard observer when using a specified illuminant. Luminous Reflectance Ratio (Contrast ratio)-- , the ratio of the luminous reflectance of surface 1 to that of surface 2 . Terminology Used for Reporting Visual Phenomena "Psychology11 1. Hue 2. Achromatic— .lacking hue; I.e. white, grey, black 3. the range of colors; i.e. blue, green, red, Saturation purple,etc.series. the degree of departure of a chromatic color from the achromatic color of the same lightness. Brightness made by apparent luminance; i.e. mental perception the estimate of luminance a specified light source with a givenadapta- tive state for the eye. 5. Lightness apparent luminous reflectance of a surface. 6. Color Contrast— -mental perception of color difference; includes hue, saturation, and lightness. 7. Lightness Contrast mental perception of lightness difference. 8. Perceptibility Difference— -total visual difference, includes lightness contrast, color contrast, shape, surface characteristics, etc. General Terms 1. Light radiant energy in that part of the electromagnetic spectrum capable of producing visual sensation. 2. Background 3* Surround the part of the field on which objects are viewed. the area around the background which falls in the field of vision. U. Field of Vision (field) the entire visual area perceived by the eye; this includes the background, and objects which influence the adaptation of the eye. 5. Color Constancy the tendency of a person to perceive the daylight color of a surface regardless of the illuminant, within limits. of the spectral distribution OBJECTIVES In view of the foregoing statements concerning the importance of the cherry industry in Michigan and the need for improvement in the visual-manual sorting operation, the following objectives were established: 1. To find a suitable method of rotating cherries as they move along the sorting belt. 2. To determine the effect of the spectral distribution of the illuminant on the perceptibility of defective fruit in cherries and tomatoes, and on the perceptibility of the color grades of tomatoes. 3. To investigate the effect of belt speed, concentration of fruit on the sorting belt, width of view of the workers, and other factors which may influence sorting efficiency in fruit processing plants. 1 W I E W OF LITERATURE Illumination for Sorting In 1951 Peterson (5 ) performed limited tests on illumination of cherry sorting "belts using blue, green, gold, and red illumination. The blue, green, and gold illumination was obtained by using a light red filter over a pink fluorescent tubo. Green and gold were eliminated because the green gave a dark appearance to the cherries and the gold did not show up all the defects (5 ). From limited tabulated data Peterson stated that higher quality cherries were obtained by using blue fluorescent lamps than white lamps; however, he stated later: The blue fluorescent lights made all the cherries look slightly darker. .. . Blue light increases the brightness (he Intended lightness) of the brown spots making them easier to detect. The black spots on the darker cherries are found be be more difficult to see. The best testimony that can be given for blue light is that the workers say that blue lights are easier than white lights for the eyes on night work. Concerning the use of red light, Peterson stated that major defects were easier to detect while minor defects, which often cook out in the can, were less noticeable. He showed the results by the total pounds of defective cherries removed by an equal number of workers under each illuminant. during the same period.Peterson's The samples were taken tabulated results indicated an efficiency increase from 5 to 88 percent for the red illumination. That is, according to the data, if the workers under white light removed 100 pounds, those under red light removed from 105 to 188 pounds during the same period. listed in the table. Eleven weight values were According to his report pink lights presented a psychological problem, especially when the light source was in the worker’s view. Also,the workers complained occasionally about changes in the illumination. Linsday (6 ) suggested the use of colored Illumination for checking color proofs. He stated, as an example, that to check a yellow proof it should be examined under saturated blue light. By this procedure the yellow ink, which absorbs blue, appears very dark If printed on white paper. That is, the white background will reflect most of the blue light while the yellow ink will absorb most of the blue light. This makes the yellow proof show up with much greater contrast under saturated blue light than under white light. The applications presented by Linsday and Peterson depend mainly on lightness differences of a surface or surfaces. The following articles on lightness are concerned with changing the spectral distributions of illuminants in order to produce greater color contrast. White (7 ) working at Stanford University considered the change in spectral reflectance and appearance as fruits and vegetables mature. His main interest was in establishing color tolerances for peaches. Spectral reflectance curves for four grades of clingstone peaches were presented. It was pointed out that the curves were very similar between 500 and 620 Mu (millimicrons). Due to this small reflectance difference in the spectral region where the eye is most sensitive to light, White suggested that photoelectric sorting of peaches be investi­ gated. The greatest difference in reflectance of the grades occurred at approximately 675 Mu. 16 White examined, raw samples of products, presumably peaches, under 1^ different sources of commercial light. The sources of illumination included white and colored fluorescents, incandescent with daylight correction filters, and mercury vapor lamps. The greatest differences in color were observed when using light with approximately equal energy di stribution. He stated: The results of numerous observations with these sources, at intensities of 10 footcandles to several hundred footcandles, consistently indicated that the illuminant allowing easiest detection of color differ­ ence did not vary with the spectral reflectance curve. The greatest differences in color for any product resulted when daylight, daylight fluorescent, daylight incandescent, or any source having approximately equal energy distribution was used. Next he used illuminant-filter combinations in order to produce light in a number of restricted areas of the visible spectrum. Thirty- six Comi n g filters used in the tests were listed and he stated that the various combinations of these filters gave hundreds of observations of different lighting conditions. In the conclusions he stated, "The light source best suited to the detection of color differences is one having approximately equal energy distribution (daylight) throughout the visible spectrum." Nickerson's (8 ) writings are not in agreement with drawn by White. the conclusions Concerning illumination for the purpose of enhancing color differences, Nickerson stated, "The single Illuminant most sat­ isfactory for this purpose will depend upon the reflectance curve of the samples to be examined." In addition she referred to studies made by Taylor (9) which indicated that the illuminant best suited to enhance­ ment of color difference is one rich in energy in the region of the 17 spectrum where the samples to he examined have maximum absorption. She continued, "In other words, if yellow samples are to he examined, an illuminant rich in energy in the blue portion of the spectrum where the spectral reflectances of yellow samples are apt to differ most vride will enable an observer to discriminate differences more easily than when UBing an illuminant deficient in the blue portion of the spectrum." A review of Taylor's (9) article revealed the following pertinent quotation concerning the perceptibility of color differences, "Our tests indicate that small color differences are often most definitely revealed by an illuminant radiating energy throughout the visible spectrum, but being especially rich in energy in the spectral regions where the colored object has maximum absorption." Taylor followed with an example which illustrated that the rich portion of the illuminant should be in the region of maximum absorption for two reflectance curves which exhibit approximately the same difference in this region as in the region of maximum reflectance. The principle of enhancing color difference stated by Nickerson and Taylor is rather well established. In a discussion with Judd (10), Head of the Colorimetry Unit, National Bureau of Standards, the writer learned that the more accurate and positive way of stating this principle is as follows: Color difference is most pronounced by use of an illuminant with radiation throughout the visible spectrum but rich in energy in the region of the spectrum where the reflectance curves of the objects exhibit the greatest percent difference. This agrees with Taylor's example but not precisely with his statements. His statements are based on the fact that for many color differences occurring in industry, 16 the greatest percent difference in reflectance is in the region of maximum absorption. Product Hotation and. Other Factors Affecting Sorting Efficiency Peterson (5) reported that some processing plants attempted to rotate cherries mechanically at the half-way point along the sorting belt. The methods listed were wooden pegs, trip wire, and a square roller. He explained that the pegs were mounted vertically in two staggered rows across the belt; the trip wire was a piano wire stretched across the belt below the center of gravity of the cherries; and the square roller was a wooden roller which rotated in the opposite direction to th§ belt travel. (Roller action was not explained further). Peterson stated, "The disadvantages of the above methods are that the first two will Jam up when squashed cherries come along, and the latter method may do mechanical damage to the product." He attempted to rotate cherries with foam rubber fingers and stated that the fingers were 80 percent effective in turning the cherries; however, the term "effectiveness" was not defined and the concentration of cherries on the belt was not given. Peterson made several counts to determine the percent of defective cherries which were visible without rotation. He stated that without rotation approximately 30 percent of the defects were visible. Malcolm and DeGarmo (ll) reported rather exhaustive laboratory tests and some field tests on factors affecting sorting efficiency in processing plants. The tests Included nine variables: objects, 2 . direction of approach to worker, 3 * objects, rate of inspection, 5 * 1. shape of number of rows of rotation of objects, 6 . percent defective, ]. location of defects, 6. color contrast of defect with that of object, and 9* effect of mirrors on inspection efficiency. The following account of the rex>ort only includes those items which were deemed important to this work. All comments apply to spherical shaped objects as reported. Malcolm and DeGarmo (ll) reported previous tests by Rossi (12) which showed that for three-quarter inch to two inch objects the sorting efficiency is increased from approximately 75 percent to 98 percent by rotating the product 3 A sorting belt. in single rows. to 2 revolutions per foot of travel on the The product in this test was presented to the worker More complete tests by the authors verified the data collected by Rossi. Malcolm and DeGarmo used 2j inch diameter objects in their teste, but reported that the size of the product was not important in this report. They also reported tests on rotation by DeHart (1 3 ) which showed that the direction of rotation should be such that the top surface of the product travels in the same direction as the sorting belt (forward rotation). When the rotation of the product was in the reverse direction the workers developed nausea at certain critical belt and rotational velocities. For spherical objects of 2^- inch diameter painted an orange color, Malcolm and DeGarmo (ll) tested three speeds of rotation: 1.93, 3-0, and k . O revolutions per foot of translation. Slightly higher sorting efficiencies were shown for the two lower speeds of rotation. In their tests the sorting efficiency ranged from 3 to 9 percent greater for the direct approach to the worker as compared to the side approach which is commonly used on sorting belts. As the width of view increased (greater number of rows of objects) the side approach showed an Improvement in sorting efficiency. "Thus, it may be conjectured the This led the authors to state, that if 6 -row presentation had been tested side approach would have equaled the inspection efficiencyobtained under the same conditions for direct approach of the specimens." Inspection efficiency was not significantly affected by the percent of defects in the samples. Samples in the tests contained lk and 30 percent defective objects. Following is a partial list of the conclusions and recommendations presented by Malcolm and DeGarmo (11)* When objects are moved (translated) along a table or conveyor belt past a grader for visual inspection for defects located on a peripheral surface, the speed of rotation of the object, while it is being moved in translation, is a primary factor in obtaining greater inspection efficiency. Spheroidal specimens, which roll about numerous axes, should be rotated about 1 .6 revolutions per foot of translation when from 3 to 9 rows are presented for Simulataneous inspection. The presentation of specimens at regular intervals along the inspection belt is preferable to haphazard spacing, from the viewpoint of both inspection efficiency and operator satisfaction. For specimens that have a maximum "width" dimension of 2^ inches, four rows of specimens appear to be the optimum number of rows that should be presented for simul­ taneous inspection. There Is reason to believe that this number of rows might not be correct for smaller or larger specimens which would decrease or increase the width of the area over which the grader*s eyes searched during the visual inspection process. For use with the side approach, the equipment should be so constructed that the grader will be stationed about 8 inches from the nearest row of objects. Defects on objects within this 8 -inch range cannot be clearly seen by graders. fEiUExTIilLlTY EITTTldl.cE From Tab J,o I tine eleven attributes of inodes of appearance aa designated by the Optical Society of America are listed as follows; trIghtneas (or lightness), hue, saturation, sine, shape, location, flicker, sparkle, transparency, glossiness, and luster. Evans (it) stated that all eleven attributes of modes of appearance can occur for the surface mode. Thus, differences between surfaces may be perceived and reported in any of these specified ways. The perceived difference is a result of the cumulative effects of the difference due to these attributes of modes of appearance and perhaps others not included in these specifications. In considering illumination as a means of enhancing perceptibility difference between surfaces, the first three attributes are of prime importance; i. e, lightnessT hue, and saturation. It is not intended to imply that changes of illuminant quality and intensity do not influence the other surface differences, but that the other factors appear to be of relative-ly minor importance in fruit and vegetable sorting. Specular gloss and transparency will be mentioned later with respect to cherry sorting operations. As set forth in the definitions, the color perceived depends on lightness, hue, and saturation. From these three attributes in combina­ tion, the eye interprets the difference in color of surfaces; i.e. color contrast. In addition, the single attribute of lightness variation is Interpreted as lightness difference; i.e. lightness contrast. Thus, the perceptibility difference may be discussed in terms of two variables, color contrast and lightness contrast. However, another very important factor, adaptation of the eye, must also be evaluated. Adaptation depends on the quality and quantity of the light reaching the eye from all parts of the field of vision; thus, the color and lightness of background and general surrounds must enter Into the analysis of perceptibility difference. An exact relationship for the calculation of the general adaptation level is not known; however, it is considered a complex function of the average reflectance of the field of view and general illumination level (if). In order to analyze the illumination in more detail, it is necessazy to consider the visual process. Only those principles and theories by which color and lightness differences are usually explained are presented. For a more detailed explanation the reader is referred to textbooks on viBion, psychology, and color. (U,15,1 6 ,17 ,18 ) The Visual Process Light entering the eye Is focused by refraction at the surface of the cornea and by the lens to form an image at the back of the eye on the retina. From the lens to the retina, light is transmitted by a medium (vitreous humor) which absorbs part of the light. The retina is made up of approximately seven million extraordinarily small receptors (cones and rods) (15). When light strikes these receptors, each receptor absorbing enough energy initiates a nerve impulse which is transmitted to the brain via a nerve fiber. electrochemical action (A). The nerve impulse takes place through The molecular basis and chemical action of visual excitation is discussed in recently reported research (1 9 ). In the central part of the retina there Is a nerve fiber for each receptor, whereas in the outer regions of the retina a number of recepco are connected to a single nerve fiber (15). (This accounts for distinct vision at the center of the field of vision), These nerve fibers are combined into a cable (optic nerve) at the back of the eye. The optic nerve is then connected to the occipital lobes of the brain in the back part of the head. An illuminated surface reflects light to the eye and results in a pattern of excitation of the retina. This pattern is trans mitted to the brain and forms a pattern of excitation on the occipital lobes of the brain which is interpreted by the brain. The resulting sensation is called visual perception. Three-Receptor Theory of Color Vision According to this theory there are three photopigments or photopigment-filter combinations which have different sensitivity to various wavelengths of light(17 ). It is not known whether these receptors or photopigments actually exist; however, the postulation of such receptors enable us to explain many observed facts of color vision (15)» Helson (2 0 ) in 1938 reported that his research on adaptation Indicated color vision is recorded by only one mechanism. However, the three receptor theory was applied by Evans (15) in 19^+8 and by Judd (17 ) in 1952. Indeed this theory has been developed to the extent that the approximate color, which will be perceived in simple visual situations, may be calculated. In order to make this calculation It is necessary to have a weighing function (hypothetical sensitivity) for each receptor and to know the spectral irradiance on the eye. follows(17)1 The formulas used are as where: is the spectral irradlance on the eye :s,'\ x > anr^ ZX are In Figure 1 aa weighing functions for the color receptors, also: * x = —■ ——— r X/X+-Y+Z , y = Y/X+Y + Z , z = Z/X+Y+Z where: x, y, and z are the trichromatic coordinates of the CZE color mixture diagram, (This is the most widely used system for color specification from spectrophotometric data. A number of systems are possible). General adaptation. According to Evans (15) the color perceived, excluding psychological factors (attitude, intention, etc. of the observer), depends on the ratio of the output of the presumed color receptors. The output of a receptor depends in turn upon its level of adaptation as well as the amount and wavelength of light absorbed by it. The level of adaptation of each type of color receptor rises and falls with the amount of light received by each. The adaptation of color receptors is most easily presented by examples. When the eye is adapted to radiation with approximately the intensity and distribution of average daylight the color receptors are adapted to what may be called equal sensitivities (1 5 ). if & small green object is brought into the field of viow, the output of the green receptors will be greater than the blue and red receptors in the region of the retina where the object is focused. The object is then perceived as TRISTIMULUS VALUES 25 0.8 400 600 500 WAVELENGTH FIGURE I. WEIGHTING SPECTROPHOTOMETRIC IN 700 20 MILLIMICRONS FUNCTIONS DATA TO USED TO REDUCE COLORIMETRIC TERMS ( |7) green in color. This is a simplified illustration) adaptation due to the image of the green object is neglected. This will be discussed later. How suppose the eye is adapted to the spectral distribution of an incandescent lamp (Figure 2 ). With the eye adapted to this spectral distribution the green receptors are somewhat desensitized compared to the blue receptors since the green receptors are receiving more radia­ tion to which they are sensitive. Likewise, the red receptors are desensitized even more than the green since the radiation is considerably greater in the red portion of the spectrum. Then, the sensitivity distribution of the eye to different colors is opposite to the spectral distribution of the radiation received by the eye (15). Receptors receiving the least radiation to which they are sensitive have greatest outputs per unit received. Color constancy. — Due to adaptation of the color receptors an observer tends to see the same color for a given object even though the spectral distribution of the illuminant is changed. This is called "color constancy" and is usually complete for object-color perceptions of ordinary changes in the conditions of illumination 0 0 . Color constancy applies to a smaller degree for illuminants with sharp changes in spectral distribution and for saturated object colors (15)* Finally, if objects are viewed under spectrally homogeneous (single wavelength) illumination color constancy is not maintained. As an example of color constancy suppose a light red object is placed on a light gray background of equal lightness and illuminated by either an incandescent lamp (Figure 2) or by north skylight (approx. equal energy distribution throughout the visible spectrum), the object will 27 100 RELATIVE ENERGY 80 60 40 20 600 500 400 WAVELENGTH FIGURE 2 . TUNGSTEN IN MILLIMICRONS SPECTRAL , DISTRIBUTION OF 29I0°K (APPROX, 150 W. FILAMENT TYPE LAMP) 700 20 appear very nearly the same color under each illuminant. For the skylight illumination let us assume the energy received by the rod receptors is twice that received by the blue receptors and both arc adapted to the same level, Then, lor the incandescent lamp the rod receptors would receive a much greater ratio of the energy, perhaps four times the b.lue receptors, since this illurainant emits much more strongly in the red region. However, the blue receptors are more sen­ sitive due to the adapting gray background and the ratio of the output of the red receptor to the blue is still approximately two to one. That is^blue receptors are relatively more sensitive,and the radiation received by the blue receptors results in greater output than an equal amount of radiation absorbed by the red receptors* Color constancy is not maintained for spectrally homogeneous or strongly saturated illuminante. Observers using strongly saturated chromatic illuroinants report that objects exhibit: 1 . illuminant, 2 . achromaticness (no hue), or 3 * mentary hue of the illuminant (20). the hue of the the after-image comple­ Furthermore, the observed hue under strongly saturated illuminants depends mainly on the lightness of the object for the specified illuminant with respect to the lightness adaptation of the eye. (Lightness adaptation of the eye depends on all objects in the field of view). Daylight hue is of minor importance. However, if a small amount of light is added throughout the visible spectrum, the objects quickly regain their normal daylight hues. Non- selective objects are slower to regain their normal daylight hues than selective objects (21). The exact daylight color may not be attained until normal illumination, whatever this may be, is restored. Thus, the C O -L O I Ox U li o t jC C t iO U y bo d X S t O x ’ ooCl by ti.iC SpoC lir a l O . i S Gx’ X O U u l O n Oi W io - illimdnant; however^ the correct hue of the ohjcct wilt he perceived if a small amount of radiation is present throughout the visible spectrum. This includes a host of so called white and even certain non-saturated chromatic illuminants. But the color of an object may not he precisely the same under any of these illuminants. (bote that col.or includes hue, lightness, and saturation)* In summary, the general adaptation of the eye makes automatic corrections for a rather wide range of spectral distributions from surfaces so that these surfaces are Interpreted as the same hue regard­ less of the spectral distribution of the illuminant, within limits. Also, color is corrected by adaptation for ordinary spectral distribu­ tions encountered in daily living. Local and lateral adaptation. The foregoing discussion has been concerned with general adaptation and color constancy. In addition, two other types of adaptation, local and lateral, must be considered. Local adaptation means the adjustment of sensitivity of a portion of the retina due to the radiation falling on that particular part of tne retina. As the eye moves from place to place over a surface, the radiation received by any particular area of the retina will be con­ tinually changing according to the changes of the field (as in reading) . Lor such a visual task the eye moves in sroall jumps from place to place and stops instantaneously to pick up the image. The focus of this image on the retina causes an Initial retinal adaptation according to the pattern of the image. This is local adaptation (l^) • At a given task with a given illumination level, local adaptation and time contribute to the general adaptation level of the eye. 30 Lateral adaptation refers to the influence of receptors which are receiving radiation on adjacent receptors* It the eye adapts locally to a spot of light of a given wavelength, adjacent receptors will also he desensitized to these wavelengths through neural interactions* If a yellow-green sad a green object are viewed in proximity, the former will tend toward yellow and the latter toward blue-green. The reason for the apparent shift in color is lateral adaptation and this is a very important effect in "simultaneous contrast" (1 5 ). As an example, when two objects are viewed in proximity lateral adaptation Is a maximum and the image of the first object will tend to desensitize the adjacent receptors to the color of the first light Suppose the two objects are green but the first reflects more blue light than the second. It these objects are viewed in proximity the blue light in the first image will help desensitize the blue receptors in the region of the second image; thus, the output of the blue receptors in the second image will be reduced. This will result in an interpretation of less blue reflection for the second object than actually exist. tendency is for the objects to be perceived as complementary. The Thus, for greatest color difference the objects should be viewed in proximity (4). Color adaptation has been discussed upder three classifications: general, local, and lateral. Likewise, lightness adaptation may be considered under the same three classifications. The Brightness Receptor In addition to the three color receptors considered in the fore­ going discussion it is convenient to assume a fourth type of receptor, the brightness receptor. For color considerations this Is actually the £>•*■fcsri re cep cox* ox the elk sy 5 com uuu _s coi±smcred soparato^.y iicxw because of its explanation, iinpox’tance In 1 Ightness corrl.ro.st and simplied by of Evans (if) uses this technic* uc. 'file sensitivity Gf this receptor to the various wavelengths of the spectrum is given by the luminosity function (figure 3) • There are many similarities between lightness and color adaptation, General, local, and lateral adaptation aPI‘ly to this type of receptor as they do to any one of the color receptors . However, it should h e .remembered that there is only one type of receptor to he considered. Tire eye is capable of adapting over a range of luminance from about 1 0 ~'/ to 105 foot-iamberts but the momentary range perceived by the eye is approximately 1000 to 1 (If). For a given level of adaptation there is an intensity level below which all stimuli appear black (if). called the black point and it increases and decreases with the level of illumination. On the other hand, white is perceived for non-selective surfaces which reflect 75 to 100 percent of the light striking surface* This is the G-ray is perceived for non-selective surfaces which have reflect­ ances between the black and white surfaces; for example, gray is perceived for non-selective surfaces in the presence of other non-selective surfaces of higher reflectance. Gray is a relative sensation depending i on other surfaces in the field; i.e. on adaptation level of the eye. Because of this dependance on adaptation level, the eye cannot be depended upon to judge absolute magnitudes of intensity but it can detect very small intensity differences (1 5 )• The ratio of luminous differences for surfaces is expressed by the contrast ratio which has been defined as follows: 32 100 50 RELATIVE SENSITIVITY 75 25 400 600 500 WAVELENGTH FIGURE 3. FOR DAYUGHT RELATIVE ADAPTED IN 700 MILLIMICRONS SPECTRAL SENSITIVITY EYE ( CI E STANDARD) (22) 20 Con crast i*o.bu_o ® A good approximation of theae Intorgrals may be obtained by summation of using narrow wavebands throughout the visible spectrum. Contrast ratio X ( 2 , L- Li. ) For calculations of this type in color determinations a waveband of 10 millimicrons (Mu) is considered sufficient for general applications (IT) • The numerator or denominator for the contrast ratio is calculated by multiplying, waveband by waveband, the spectral distribution of the illuminant by the spectral reflectance of the object by the luminosity function of the eye, and by totaling the products throughout the visible spectrum. It is noted again that this calculation depends only on one receptor sensitivity curve while the color calculations require the inclusion of data from three color receptors. This is important in the consideration of lightness differences. Suppose the eye views a scene which adapts the brightness receptors to the same level when illuminated by certain intensities of either a daylight fluorescent lamp or an incandescent lamp. If two objects of different spectral reflectance are viewed under each illuminant, the objects will tend to maintain their own color since color adaptation tends to make up for color deficiencies in the illuminant. However, * The summation limits from ^00 to 720 Mu are omitted for convenience. These limits are used throughout this report and are justified since the luminosity function, L, is practically zero beyond these limits. A 10 Mu increment is used unless otherwise specified. if one of the objects has greater luminous reflectance than the other under the incarescent illuminant the eye will make* no correction for the difference in contrast ratio produced by change of illuminant. That is, there is no lightness constancy as found for color when the spectral distribution of the illuminant is charged. Thus, the lightness difference due to change in the spectral distribution of the illuminant is not corrected by adaptation of the eye since there is only one type of brightness receptor (if). In addition to local, lateral, and general adaptation, light is reflected from the image on the retina to other parts of the retina, This Is called entoptic stray light and results in excitation of these regions which increases the level of adaptation (2 3 ). Principles of Perceptibility Difference The following principles concerning optimlum visual conditions for perception of color and lightness differences were taken from the indicated reference, Tor maximum perceptibility of color differences. 1. The surfaces should be viewed in proximity (h). 2. The illuminant should radiate energy throughout the visible spectrum but should be rich In energy in the region of the spectrum where the reflectance curves of the surfaces exhibit the greatest percent difference (1 0 ). 3. Judd (1 7 ) states, "The most favorable condition for detecting chromaticity differences (Schonfelder, 1933) is to have the eye adapted to a chromaticity as closely like the two being compared as possible." This means that the color of the background should be the average color of the product being graded.* iv,u iiiaxlmum. p f > 1 Or OJ Q TO 7 2 0 Mu FOR CHERRIES AND DEFECTS UNDER DELUXE WARM W HITE FLUORESCENT LAMP 53 80 60 LUMINOUS FLUX (PERCENT OF TOTAL) 100 REFLECTED 40 20 ( X) FIGURE 13 FROM 600 500 400 WAVELENGTH IN 700 20 MILLIMICRONS PERCENT OF REFLECTED LUMINOUS FUUX INCLUDED “X TO 7 2 0 Mu FOR CHERRIES AND DEFECTS UNDER 2 9 I0 °K TU NG STEN LAMP 54 25/1 5/1 CONTRAST RATIO 20/1 10/1 5/1 DELUXE B 1H 600 500 400 ( X) WAVELENGTH IN 700 MILLIMICRONS F IG U R E 14 CO N TR A ST R ATIO FOR BLACK DEFECTS WHEN INCLUDING REFLECTED LUMINOUS FLUX FROM X TO 7 2 0 Mu 20 55 3/1 RATIO 2/1 I /I 2flC^K "[UliljSS]l£ CONTRAST F IIIO 1/2 1/3 1/4 600 500 400 (X) WAVELENGTH IN 700 20 MILLIMICRONS FIGURE 15. CO NTRAST RATIOS FOR BROWN AND UNDER-COLOR DEFECTS WHEN INCLUDING REFLECTED LUMINOUS FLUX FROM X TO 7 2 0 Mu Together Figures 11 to 15 show the various combinations of contrast ratios and percent of luminous r e f .ectancc from cherries and cherry defee ts wh_ch arc xllumanatcd by that part of the spectrum. from 720 Mu with tho specified illuminant. go Those curves show that the 29IC0 h tungsten lamp possesses the greatest possibility of increasing the contrasi ratio of dark defects* Using the curves for the tungsten lamp, if that part of the illumination from tOO to 6l0 liu were eliminated, ob percent of the total luminous reflectance from the red ripe cherries would be included (Figure 13) and the contrast ratios for black and brown defects would be 12,7/1 and 1*55A , respectively (Figures l^ and If). In addition, the elimination of this portion of the spectrum would greatly reduce the adaptation level of the eyes. This lower level of adaptation should provide improved visibility of the cherries since a lower level of adaptation would be closer to satisifying the condition of uniform field lightness, ‘ This same analysis may be applied to the fluorescent illuminants but with less success in including an equal percent of the reflected luminous flux from red ripe cherries and at slightly lower contrast ratios for the same wavelength, X . Since the contrast ratio for tho under-color and brown defects was increased only slightly, Figure l6 Is presented in order to consider the use of the portion of the spectrum from "X-to hOO Mu. From these curves the maximum contrast ratio for brown and under-color defects is l/l.8 and l/3 *9, respectively. Using the G. E. daylight fluorescent lamp without filters, the corresponding ratios are l/l*h and 1/3 .1, respectively* Observing again Figure 5 , it appears that no large CONTRAST RATIO 2/1 I/I 1/2 1/3 1/4 ( *) FIGURE 16. DEFECTS 600 500 400 WAVELENGTH IN 700 20 MILLIMICRONS CONTRAST RATIOS FOR BROWN AND WHEN INCLUDING REFLECTED LUMINOUS X TO 4 0 0 Mu UNDER-COLOR FLUX FROM increases in contrast ratio acre possible lor these defects by using other portions of the spectrum. In summary, by application of filters to fluorescent lamps, the contrast ratio for dark defects may be increased considerably and at the same tune a large part of the reflected luminous flux from the red ripe cherry may be included. The 2910° K tungsten lamp shows the greatest promise in accomplishing these objectives. under-color defects it appears For the brown and that the contrast ratio may be increased only slightly by use of filters; the G. E. daylight fluorescent lamp without filters gives nearly as good results as illuminant-filter combinations. Coiomerically available filters* In order to test the effect of increasing the contrast ratio on the perceptibility of cherry defects, it was necessary to obtain filters which would increase the contrast ratio for the dark defects, and compare the illumination produced in this manner with regular illuminants. It was decided to use low cost gelatine filters for this purpose and a number of filter samples were obtained from manufacturers. A sample of cherries and defects was obtained and viewed by placing various filters over the eyes and observing the apparent differences in lightness contrast. in the observations. A total of seventy filters were used Twelve filters were chosen and transmittances obtained with a spectrophotometer.* their spectral Also, four wratten filters with known spectral transmittances were provided by the Eastman ^Transmittance curves were run on the 3 ame spectrophotometer as discussed in the appendix for reflectance curves. Band width was Maintained at 12.9 Mu or leas. Kodak Gompany. The brcsvn or/l black defect contrast ratios obtained by applying these sixteen filters to G. f . deluxe warm white fluorescent lamps are listed in Table III. increments. The calculations were made at 20 Itu Since this increment is rather large these ratios are considered only as approximations for selection of several filters for field test. The highest range of contrast ratios is approximately 1.6/1 for brown to 11.3/1 for black defects for filter B- 29. This and other contrast ratios shew that it is possible to increase the contrast ratio by use of commerically available filters. From the group of filters considered filters B-7* B-ll, B-23, and. B -67 were selected for field tests. In making these selections the contrast ratios, luminous flux reflected from the red ripe cherries, and the appearance of the cherries and defects by filtered light were considered. TABLE III Contrast Eatios and Luminous Flux Reflected from Cherries Illuminated by G, F. Deluxe Warm White Fluorescent Lamp with Commercial Filters Filter Dsed to Cover Illuminant* none K-9 , yellow K-15, deep yellow K-25, red K-29, deep red B-6, rose pink B-7 , dark rose pink B-10 , light magenta B-ll, medium magenta B-13, rose B-20, light purple B-23, medium purple B-59, amber B-60, dark amber B-63, spec. It. red B-65, medium scarlet B-67, fire red Contrast Ratio Brown Defect Black Defect 1/1.15 1/1.15 1/1 .1 5 1.22/1 1.62/1 l.Ol/l 1 .0 4 /1 1.13/1 1.19/1 1 .4 9 /1 1 .4 8 /1 1 .4l/l l/l.ll 1/1.06 1 .1 4 /1 1 .2 5 /1 1 .4 1 /1 3.11/1 3.22/1 3.38/1 7 .4 4 /1 11.26/1 5.05 A 5.52/1 5.70/1 6.60/1 9.30/1 6.50/1 5.90/1 4.00/1 4.36/1 6.35/1 7.50/1 9 .4o/l Relative Luminous Flux from Red Ripe Cherries per watt *■* 253 220 210 134 87.6 l6l 148 117 114 100 38.4 5 2 .5 186 170 133 109 94 * Filter numbers are those designated by the manufacturer, East­ man Kodak Co., Rochester, N. Y.; Brigham Gelatine Co., Randolph, Vermont. "K1' indicates Kodak and "B”, Brigham. ** Calculations were made at 20 Mu increments. PERCEPTIBILITY OF DEFECTIVE TOMATOES Reflectance curves for red ripe tomatoes are presented in Figure 1 7 . In the discussion of tomato curves (Appendix I) it is noted that con­ siderable specular gloss entered into the measurements. Therefore, the curves actually should show lower reflectance by approximately 5 to 15 percent. The lower value applies to the short wavelengths and the higher to the long wavelengths. Laying aside this fact, the shape of the red ripe tomato curves are similar to the red cherry curves. of the defects are in the same range as the brown cherries. Some to black defective No reflectance curves were run for defective tomatoes; however, the reflectance curves for red ripe tomatoes indicate that the analysis used for dark defective cherries should also apply to dark defects on tomatoes. Observations were made at two tomato processing plants using filters over the eyes to simulate chromatic illumination. Dark defects and green spots appeared very dark and the tomatoes much lighter when using the same filters as employed in the c h e n y analysis. It was noted that the green spots should have appeared darker since the filters transmitted very little green light. Thus, it is concluded that dark or green spots on ripe tomatoes may be enhanced by use of filters similar to those listed for cherries. The problem of removing defective tomatoes Is not as acute as the cherry sorting problem because fewer tomatoes pass the observers per unit time and the defective spots are usually larger. 62 90 80 70 60 50 40 30 20 10 , 0 I I 20 I 40 I i I 60 I 80 1 1 500 _ _ _ _ _ _ _ _ _ _ _ _ 20 40 WAVELENGTH FIGURE 17. FOR i i 60 !_ _ _ _ _ _ 80 600 20 I_ _ _ _ _ i- - - - - - 1_ _ _ _ _ 40 60 __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 80 IN MILLIMICRONS 4 5 ° - 0 ° SPECTRAL REFLECTANCE MICHIGAN GROWN TOMATOES CURVES 700 20 COLOR GRADING TOMATOES The color grading problem for tomatoes was divided into two parte in the introduction: 1* grading tomatoea which are shipped into the state during the winter months into four color grades (green, light pink, pink, and red) and 2. grading Michigan tomatoes for canning into grades one, two, and culls. For the former problem, observations were made of the various color grades of tomatoes by using filters over the eyes to simulate chromatic illumination* The filters were selected from the college stores supply by use of a wedge interference filter which showed the color of illumina­ tion transmitted by each filter. The filter colors were straw, medium amber, pink, light red, light magenta, dark rose purple, light blue, and green. In general, there was little effect on color or confusion of color when filters were used over the eyes. Filters of low saturation gave only small changes in colors and those of high saturation caused con­ fusion of certain colors. It appeared that none of the filters used would be suitable for grading tomatoes into four color grades, AJfter reflectance curves of tomatoes were obtained it was noted that the reflectance of the color grades varied with respect to each other In several different regions of the visible spectrum (Figure 18). Besides,the reflectance for pink tomatoes had considerable variation (Figure Lo). Thus, it did not appear possible to enhance differences between four color grades by any single chromatic illuxninant. It is not 6k 90 80 70 60 50 40 30 20 10 0 ' i 20 l 40 l ' 60 l l ' 80 500 _ _ _ _ _ _ _ 20 40 WAVELENGTH FIGURE 18. FOR : _ _ _ _ _ _ _ i 60 IN I 80 I 600 i 20 1 40 I , 60 I_ _ _ _ _ _ _ _ _ _ 80 MILLIMICRONS 4 5 ° - 0 ° SPECTRAL FLORIDA GROWN REFLECTANCE TOMATOES CURVES L- 700 20 65 practical to use two or throe types of illumination which would specialize sorting along the belt since the relative number of each grade is quite variable. Referring to the previously mentioned color principles, an illuminant with a spectral distribution throughout the visible spectrum should be used. No conclusions can be drawn as to whether this illuminant should be rich in a particular portion of the spectrum. For analysis of the problem of grading Michigan grown tomatoes into grades one and two, reflectance curves for the Rutger9s variety were run. Two curves from tomatoes' of each of these grades are presented in Appendix I. The average for each type is shown in Figure 17; red ripe represents number one tomatoes for canning and light red number two tomatoes. From these curves it appears that the illuminant should radiate throughout the visible spectrum but may be especially rich in energy in the region of ^>30 to 6^0 Mu. However, before making any definite recommendations, additional reflectance curves should be run since these curves are based on only two samples and their difference is small. This is necessary in order to be sure that the correct reflectance curve for tomatoes of the two grades has been obtained. It is noted that the workers use firmness as a criterion for separating these grades and that some operators are not aware of any particular grading difficulty. Perhaps the nature and need of improvements in this type of grading should be investigated. PRODUCT ROTATION It has already been shown that viewing the entire surface of the product is an important factor in attaining high sorting efficiency. One common method of rotating large fruit (apples, potatoes, etc.) is the roller conveyor. This piece of equipment brings most of the surface of the fruit Into the worker's view and undoubtedly the sorting efficiency is higher than attained on sorting belts which only translate the product. Another method of rotating the larger fruit, spaced rods which travel at a different speed than the sorting belt, was used on a test machine by Malcolm and DeGarmo (11). Peterson (f) reported that several methods had been attempted in cherry processing plants for rotation of smaller fruit (approximately three-quarters Inch in diameter) but no satisfactory solution was presented. The work presented here was performed with cherries and should apply also to berries and other small spherically shaped fruit. Fourteen devices were considered originally for rotating cherries. A sketch and description of operation was prepared for each. These were discussed with many interested persons and four devices were chosen for preliminary tests. Preliminary Teat Using Marbles In the laboratory four devices were tried for rotating cherries on sorting belts. Three of the devices, a rotating roller and two types of deflection plates, are shown in Figure 19* The fourth device consisted of a one inch pip© with a slit cut along one side. Air pressure was 67 iu a O O _J 3 a: CO £ UJ _l < o oc o C O ro x O N co SORTING co z BELT UJ N C O GO co LjJ CHERRIES N ro CO C O Q O tr O Ui >- LU < a: 00 o UJ X FO R a UJ CM DEVICES CD S co CM U1 -I GO co lii H tr UJ £ H < UJ Z 2 s < □ Q UJ a go uj s (O ^ VC. 15 UJ UJ C O2 2 UJ *“ < X Q a: U TJ = C M o IE * ^ 19. ro s. ro C O £ UJ > UJ o C O FIGURE O. ROTATING ro 5 68 applied to blie pipe and a sheet of air directed from the elit onto the proouc I, The impact of the high velocity air caused the marbles to roll provided there vac an empty space on the belt. However^ air pressure did not appear to he economically feasible end the workers would prohahiy object to tho air blast. Preliminary tests using tho first three devices to rotate 3A diameter marbles at various belt speeds are shown in Tabic IV. inch Since marbles were uniform in size and had different surface characteristics than cherries> these data were considered only as an indication of the efficiency for rotation of cherries. Rotation of Cherries During the cherry season two devices were tested for rotation of cherries on sorting belts and a third device was tried in the laboratory. TABLE IV Percent of Three-Quarter Inch Diameter Glass Marbles Rotated by Devices on Sorting Belt Belt velocity ft,/ min. Dr" Defl. Plate Rotated Rotated Ip0 ° or 9 0 ° or more more 3/8” Diameter 3" Defl. Plate Rotating Rod * Rotated Rotated Rotated Rotated 150 ° or 90 ° or 150 ° or 90 ° or more more more more 27 10 91 21 8 98 82 31 11 68 90 92 31 11.9 90 30 97 2 0 .0 99 k2 99 2 5 .0 19 8 3 0 .0 37 2k * Peripheral velocity of rotating rod was 37*^ ft/min. 69 Rotating rod. A roller wua mounted across the "bolt and rotated lo cause the cherries to go over It (see Figure 19). Tho roller was made of a 9'/l6 inch steel rod wrapped with friction tape: which served as a friction coating (Y/l6 inch overall diameter). The friction coating turned tho cherries as they were lifted over the roller. The peripherul velocity of the roller ranged from 29 to 60 feet per minute. Bolt velocity was 2 k feet per minute. The procedure for tests was as follows. Cherries were placed on the holt one layer deep in front of the roller and. the belt was run for 6 inches in order to minimize friction on the stationary fruit guards (sides of table) during the test. A mixture of white paint pigment and flexible collodion was used to paint two rows of 90 cherries each across the belt. was started. This paint dried in one or two minutes and the belt When both test rows had passed over the roller the belt was stopped.and a count made of all cherries rotated 90 ° °r more and those rotated I5 O0 or more. Another count of the total number of cherries was made as the painted cherries were removed from the unpointed cherries before the next test. It should be noted that the 90° and 150° are only approximate since the writer’s Judgement was used to determine this factor. An effort was made to count each test in a similar manner. Plates II and III show pictures which were taken before and after rotation of cherries with the rotating rod. Results of the tests with the rotating rod are shown in Figure 20. The efficiency of this device is shown by W o curves which give the percent of cherries rotated 90 ° or more and the percent of cherries rotated 150° or more. The peripheral velocity of the roller was twice 70 th© belt velocity at maximum efficiency. PLATE II. Before Test of Rotating Rod. Fifty cherries were painted in each row. PLATE III. After Test of Rotating Rod. Many of the one hundred painted spots were turned under. m PLATE IY. Stationary Rod. Mounted on Sorting Belt in Processing Plant. This belt is lightly loaded with cherries compared to Plate I. 71 in in UJ CD UJ Ll. O X m O CO o o z * o o CO z o h ir fc < x Jr - uj o x ^ o u_ 10 ro >o O UJ UJ ti­ is O X ro ^ o 04 UJ UJ in £L 001 CSJ 04 Q31V10H S3ldd3H0 30 1N30 d3d x Li- t X e> x 72 stationary rods. Tests were c.rducted on three sizes of station­ ary rods (Figure 19) in the labora/tory and at one processing plant using red tart cherries. At the plant the l / 8 and 3/16 inch rods were left on the belt during actual sorting operation (Plate IV.), They operated satis­ factorily except for catching a small amount of trash. Cherries rotated in front of the rod until other cherries forced them over the rod. appeared The This to be responsible for much of the turning action. procedure for tasting the stationary rode was similar to that used for the rotating rod. The correct percent of the belt covered with cherries was obtained by covering one secton of the belt with one full layer and then spreading the cherries to twice or four times this area to obtain 50 percent and 25 percent cover, respectively. The rods were mounted tightly against the belt and the belt supported under tii3 rod by a flat metal plate» Preliminary tests showed that the 3/32 inch rod was rather in­ efficient; therefore, it was eliminated. The data for the l / 8 inch and the 3/l6 inch rod are shown in Figure 21, "variable belt speed test" represents Each plotted, point for 100 cherries and each point for the"percent of belt covered test" represents 200 cherries l/ 8 for the inch rod and 400 cherries for the 3 /l6 inch rod. From this data it appears that the 3/l6 inch diameter rod is slightly better than the l/ 8 inch rod when the belt is not fully covered with cherries. It is shown by the left group of curves that the efficiency decreases as the belt speed increases, Also both groups of curves indicate that efficiency is improved by decreasing the concentra­ tion of cherries on the belt. 73 CO UJ Ul UJ i_ a: !□ cr UI ui CVJ Q UJ v "go £ p o ^ O O O ° Q a:k £ £ o o Ul UJ ui cr a: o o cr cr o o UI I3 o a U) ui ♦ O o cr -i UJ -Q- ~ a cr cr cr cr u j u i xj cr o o o o u i u j § § o 21. ° cr 2 cr cr cr u CVJ 2 o 2 ro ° ro 100 in O CO 031V10H CHERRIES ON SORTING STATIONARY ROD UJ UJ O o S3IHH3H0 30 1N30 83d O FIGURE Q q UJ z ^ BELT m ^ < UJ o OF WITH 5 uj uj ROTATION cr o co x The two sets of data in Figure 21 are not in close agreement} especially for 100 percent cover. This is attributed to the fact that the cherries used in the test for the left set of curves were moreuniform in size. In any case, the efficiency is rather low when the belt is fully covered with cherries. Deflection plate ^ . ho actual tests were conducted on the use of deflection plates to rotate cherries; however, a deflection plate was inserted on the belt in the laboratory and cherries run over the plate. In the limited observations, the cherries went over the plate without crushing. This type of device may have some advantage over the station­ ary rod since its larger friction surface should have a tendency to cause more rotation than that of the stationary rod, especially if the belt is fully covered. However, it may have greater tendency to collect trash and become objectionable from the standpoint of sanitation. Some dead cherry stems were caught under the stationary rod during regular plant operation. If the deflection plates could be mounted with hinges in order to facilitate cleaning, they may be as satisfactory in this respect as the stationary rods. OTHER FACTORS IK SORTING- EFIICIEI'JCY There are a number of factors other than lighting and rotation of the product which may affect the sorting efficiency of cherries and tomatoes. Malcolm and DeGarmo (ll) investigated the nine factors listed in the review of literature. Rate of Inspection The highest rate of inspection tested by Malcolm and DeGarmo (11) was 500 specimens per minute. The inspection rate for cherries is at- least twice this value in many plants. are smaller. However, it This Is expected since cherries appears that a better standard for the rate of inspection would be the area of fruit passing a worker per minute. Such data would have more general application since the size of fruit would not be included in the measure of rate. It seems that this measure should be in agreement with the idea of cone of distinct vision and/or pattern of eye movement. Another basis for rate of inspection might be the number of defect­ ive specimens passing a worker per unit of time. If this factor were defined, the processor, knowing the approximate quality of the fruit from inspection at the receiving station, should be able to regulate the flow of the product according to percent of defective fruit. The advantage of this procedure would be that the workers could be provided with enough fruit to keep their hands busy removing defective fruit. This should increase labor efficiency, and future research might well consider these possibilities. 76 Viewing tho Entire Surface of Product In addition to rotating fruit as it moves along the sorting belt, some cherry processing plants have a problem of spreading the fruit on the belts and preventing it from riding too close to the fruit guards which obstruct the view. One plant in which the writer worked used a splitter at the head of the belt to divide the cherries into two groups. This appeared to help some in spreading the cherries. Also^ the devices developed for rotation of fruit helped spread the cherries over the belt. The two rows formed by a splitter and the spreading effect of the station­ ary rod may be seen in Plate IV. This sorting belt is rather lightly loaded (perhaps 20 percent cover). For fruit which rides too close to the fruit guards baffles may be used to force it away from the sides. Some processors have noted that workers often reach to the far side of the belt to remove defective fruit. It appears that a part­ ition down the center of the belt may be useful for limiting the width of view and preventing workers from watching the otherside of the bolt. A center partition has been used in some plants but it whether its use improves sorting efficiency. is not known Perhaps this factor could be included in future research. Sorting Cherries by Transmitted Light Looking to the future it appears that cherries, due to their trans^ parency, may be sorted by transmitted light. Some observations were made in the laboratory using pitted and unpitted cherries on a glass plate with two to four 150 watt incandescent bulbs underneath. A picture 77 of the arrangement is shown in Plate V. Unpitted cherries are ahcrwn on the left, under-color cherries in the center, and dark defective cherries on the right of the picture. When the cherries were viewed normal to the surface of the glass, perceptibility of defects was greatly reduced due to glare caused by the lamp bulbs even though defusers were used over the bulbs. Therefore, viewing at such an angle that the bulbs would not come into the field of vision was absolutely essential. Perceptibility of dark defects was increased when the bulbs were not in the field of vision. Perceptibility of dark defects was increased slightly more by placing filter B - 2 3 under the glass plate or over the eyes. It occurred to the writer that viewing the cherries by transmitted light, at such an angle that no direct radiation is received from the lamp bulbs, gives to some extent the same effect as eliminating a large part of the blue and green portions of the spectrum. This follcws by reasoning that the glass will transmit a large part of the radiation but that some diffuse rays will be reflected and reach the observer’s eyes indirectly. For the rays which strike the cherries most of the green and blue wavelengths are transmitted. absorbed and only the red wavelengths are The red light is then diffusely scattered by the cherry and received by the eye. Where a dark spot occurs most of the radiation in the visible spectrum, is absorbed. Thus, the eye receives some radiation throughout the visible spectrum but receives only long wavelengths of light from the cherry Itself. It is believed that the principle of sorting by transmitted light is rather similar to using a filter with transmittance similar to the cherry reflectance curve from PLATE V. Kodachrome Picture of Arrangementfor Observation of Cherry Defects by Trans­ mitted Light, This sample was illuminated from above by two photoflood lamps. approximately 600 to 720 Mi and with a small amount of transmittance from h O O to 600 Mu. The level of illumination necessary to increase perceptibility of defective cherries by transmitted light is rather high. It appears from observations that the perceptibility of dark defects in cherries is equally enhanced by reflected light if an equal intensity of illu­ mination is used with a filter eliminating the green portion of the spectrum as discussed previously. This statement is based limited observations and perhaps further investigation on rather of sorting by transmitted light would be justified. Fluorescence of Defective Cherries It is known that certain types of organic decay will fluoresce if irradiated with ultraviolet energy. The writer used a high pressure mercury arc lamp which has a group of spectral lines near 3^5 Mu to irradiate brown and black defective cherries. However, with the eyes dark adapted, there was no visible fluorescence from the defective cherries. 79 ■Specular Gloss Due Du Ike smooth surface of cherries and tomatoes, non-seiectiye specularly reiiecoed iigiib (specula:.' gloss) produces an i m g s of the light source on each piece of fruit. Point sources of light will cause these images to he quite distinct. rl_ti.irc illumination minimizes effects of specular gloss and improves perception of glossy surfaces . This should he easier on the eyes. field tests were conducted at three caerry processing plants. Procedure lor the tests was as follows, Two sorting "belts which were as nearly alike with respect to color, speed, -Location, etc. wore selected. "belt. An equal number of workers inspected‘the cherries on each Filters were placed over the illuminant on one "belt' and the other "belt was operated with the sarae type of illuminant without a filter. 'On the test with fluorescent lamps, the number of tubes was tripled where filters were applied. For incandescent lamp tests, the number of bulbs was doubled for the belt with the filter. In operation, a cherry sample was taken before the cherries were sorted. Another sample was taken from the same batch of cherries, after sorting, at the end of each sorting belt. In order to take samples from the same batch, the time required for a cherry to travel from the first sampling location to the end of each sorting belt was obtained with a stop watch. samples. An ordinary watch was used to time the spacing of Samples were marked with code letters to indicate their locations and given to a sample inspector to separate and classify the defects. The U.S.D.A. inspector at the plant helped train the sample inspector to properly classify the various types of defects. Checks were made with the U.G.D.A. inspector when doubt arose, until the sample inspector was throughly familiar with the defects. Code markings eliminated any chance of prejudicial opinions on the part of the sample inspector who had to make the critical decision of the classification of major and minor defects, An effort was made to eliminate any effects due to differences in •worker efficiency and differences due to belts. In order to accomplish this, the chromatic illuminants were used on each of the teat belts for one-half of each test. It is believed that belt and worker differences were successfully eliminated in the tests at the last two plants. Complications at the first plant will be explained later. Another variable was the variation iri tho percent of defects and the type of defects. Since the sample was taken from the same batch of cherries from both belts, it is assumed that these factors had negligible effects on the results. At times the flow of cherries to the plant fluctuated. This caused the flow of cherries to various sorting belts to be uneven. Usually the flow smoothed out soon or the operator changed the regulators to adjust the flow. No corrections were possible for this variable but the flew into the plant on the main belt was observed before taking a sample in order to avoid taking samples during any noticable fluctuation. The plant was allowed to operate at least Yj minutes before any samples were taken. This permitted the flow regulators to be adjusted and allowed time for the eyes to adapt to the prevailing visual conditions. Illumination was measured with a Weston Model 6 lt light meter (AE-763) which compared closely with the recently calibrated General Electric type P-12 light meter (AE-I567) and an approximate correction factor for chromatic illumination produced by each illuminant-filter combination was calculated and applied. The correction factor (E) was determined from the following ratio: L T - ___ ^ L A ) 3:__ ) Meter reading (with filter) = (F)---- — ---- -------- ---- ---Meter reading (without filter) The ratio on the left-hand side of the equal sign is the luminous transmittance of the filter. The ratio on the right-hand side (omitting F) is the luminous transmittance of the filter as meter. determined by the The correction factor (F) is a multiplying factor to he used for correction of Weston light meter readings, specifically readings of meter AE -7 6 3 which is not corrected for color. It should apply approximately to other uncorrected light meters. Tests at Plant A The arrangement of the sorting helts in plant A and the sampling locations are shown in Figure 22. This plant was chosen mainly “because there was very little interference from outside daylight. With all lamps turned off the illumination falling on the sorting helts was less than one foot-candle. The “belt illuminant consisted of 40 watt T-12 standard cool white fluorescent tuhes mounted end to end approxi­ mately l6 inches ahove the helt. A curved piece of sheet metal served as a reflector ahove each tube. The reflectors were painted with a good grade of white paint and the standard cool white tuhes were replaced with G> E. deluxe warm, white tuhes. On one helt two extra tubes were mounted on the flanges of the reflector; this gave almost three times as much illumination as on© tube. The filter was mounted over the three tuhes of the illuminant. 63 co CD uj <0 5E 5 cc N . ro O W O X UJ _i < o CO 1S31 FIGURE q 1138 22. FLOOR PLAN AT PLANT < 84 As explained previously four filters were chosen from the cal­ culations and observations, The statistical arrangement of the tests were planned as follows: Four filters: 1,2,3, & 4 Two belts: a 2c b Two crews: A & B Period of day 1 2 3 4 1 st day 1a A 3a B 4b A 2b B 2 nd day 2TB 4 a A 3 b B IbA 3rd day 3"b~A 1 b B 2aA 4aB 4 th day 4"T'B 2b A 1 a B 3 a A The filters used and the approximate illumination on the belt are shown in Table V. (Spectral transmittance curves for these filters are presented later). Black belts were used and the belt speed was 20,4 feet per minute. . Eleven workers were used on each belt. TABLE V Filters and Illumination for Tests Using Deluxe Warm White Fluorescent Lamps at Plant A Filter Factory Designation (F) Approx, Meter correction factor* Range of Illumination on belt(foot-candle 1 3-23, Medium purple 0.4 28-41 2 B-ll, Medium magenta 0 .1 53-41 3 B- 7 , Dark 2’ose pink 0 .8 05-125 4 B- 67 , Fire red 0.5 33X3 comparsion illumlnarit 0 .9 ** 6 0 -1 2 0 none * Estimated 10 percent accuracy * * Reference (25) 85 During the first day, samples of approximately 100 cherries were taken at each sampling station. With this size sample the variation in percent defects was so great that occasionally there were raore defects in the sorted cherries than in the unsorted cherries; samples taken thereafter consisted of 300 to kOO cherries. The tests were continued for two days taking the larger samples. The results from these tests were inconclusive since only one-half of the test "block was completed. cherries and for the number The summary of totals for the number of and percent of major defects (both brown and black) in sauries are shown in Table VI. Theoretically, all filters should have improved the perceptibility of the black defects and any brown defects which were darker than brown rot. Actually, the results of the incomplete tests (Table VI) indicate sorting efficiency was Improved for both brown and black defects when using filters B-ll and B -6 7 but that sorting efficiency was decreased by use of filter B- 7 . Results for filter B-23 Indicate that sorting efficiency was Increased for the black defects and decreased for the brown defects. In addition to this inconclusive data, opinions of the worker's were taken. It was evidont from their comments that filter B -67 would not be successful even though the produced for enhancing the defects. illumination indicated merit Some workers complained of eye strain and headaches when this filter was used over the illuminant. About the same complaints, except not as severe, were leveled against filter B- 7 . This filter had indicated no merit in the test. Thus, it was decided to eliminate these two filters from further tests and to move to a different plant with a new sot of workers who would not be Influenced 86 TABLE VI Summary of Test at Plant A Using Deluxe Warm White Fluorescent Lamps and Filters as Indicated Illuminant Total cherries in samples Total Brown Total Black Defects Defects No. Before Sorting 3180 136 No Filter 3183 Filter B -7 of P No. $ Percent Sorting Efficiency* Brown Black 4.28 94 2-95 69 2 .1 6 51 1 .6 0 k-9.6 4-5.8 2977 87 2 .2 5 63 2 .1 2 47.4 2 8 .1 Before sorting 2658 119 4.48 99 5.72 No Filter 2576 9b 3.65 50 1 .9k 1 8 .^ 47*7 Filter B-ll 2658 51 1 .9 2 kl 1.94 57*0 5 8 .6 Before Sorting 2623 138 5.29 79 3.01 No Filter 2821 77 2 .7 2 65 2 .3 0 48.1 20.3 Filter B-23 2680 122 4.99 1*0 1.49 11.5 90.5 Before Sorting 3098 138 4.92 91 2 .9 8 No Filter 2932 89 3 .0k 51 1.74 32.7 41.7 Filter B -6 7 3069 64 2 .0 8 39 I .27 54.0 97.3 * Sorting efficiency is defined as 100 percent if aJLl defects are removed. 87 oj "the adverse co;incuts conccrnii;^ filtore ->• . ‘ Teats at I.Lint B Tho arrangement of the sorting Dolts and the sampling -locations for this plant arc 3hown in Figure 2 3 . Incandescent filament lamps were used in an inverted trough fixture which was approximately ten Inches across the opening and extended the entire length of the sorting "belt. Illumination from three spectral distributions arc given below. The appropriate correction factors were applied. Each 1. Skylight varied with the time of day and location on tho sorting belt from 3 to 30 fcot-candlcs. (3 0 fcot-candles was the maximum from measure­ ments at beginning and end of tests). 2* Light from 6-100 watt bulbs varied with location on the sorting belt from tO to 80 foot-candles. 3. Light from 12-100 watt bulbs with filters were: Filter B-ll; 20 to ho foot-candles (F= 0 .6 ) Filter B-23; 12 to 25 foot-candles (F= 0.5) t. Other pertinent information is as follows: Belt speed: 30.1 feet per minute Belt color: white ITumber of workers: six per belt sorting belt had an It was necessary to take a belt. Individual feeder. With this arrangement sample before and after sorting for each Thus, four samples instead of three were taken. The belt was timed as before and samples were taken from the same batch of cherries before and after sorting. Each cherry sample was taken in three parts with 100 to 150 cherries in each part. This prevented taking too many cherries from one location on the belt, which would disrupt even flow, and distributed the time of taking the samples over a longer period. 83 ro LU 1S31 r 31009 o DNIldJWS 1139 23. UJ FLOOR to 1S31 ' v j 2 CO o y O C£ h- a: 3 UJ o x FIGURE q 1139 PLAN AT PLANT r:— 89 The tost 'time for each filter was four hours. At tho end of the first two hours the ertra laths a ad filter wer^ switched to the ether holt. The workers remained in th^lr positions. each crew of workers and each "belt were used with the chromatic illumination for one-half of the test. Four samples wore taken from each sampling; location during each two hour period of tho test (one-half the test). That is, for the four hour tost for each filter, eight samples wore obtained for each illuminant. The totals of all samples and percentages of major defects arc shown in Table YII. Only the major defects wore counted in the test. For determining the percent removed, each belt was considered independently since each bolt had an individual feeder. from the same large storage tank). (Actually the cherries came The percent sorting efficiency was considered 100 percent if all defective cherries were removed. The results shown in Table VTI were not statistically significant at the 95 percent confidence interval* There was one complaint about the illumination pi’oduccd by filter B-ll. The worker stated that the illumination caused dizziness; however, there was no general dislike of the illumination. The illumination produced by filter B-f 3 was well liked by the workers. Several workers made favorable comments concerning the improvod perceptibility of defects and some stated that this illuminant was easier on their eyes than the regular illuminant. There were no complaints of dizziness or headaches when using filter B- 2 3 * Since the illumination produced by using B-23 showed promise of being superior to the regular illumination provided by incandescent 90 TABLE VII Summary of Teste at Plant B Using 100 Watt Filament Type Incandescent Lamp and Filters as Indicated Total Cherries in Samples Major Defects Total Brown No. Percent Sorting Efficiency Total Black 1° No. 1> No Filter Before sorting 2657 105 3.96 50 1 .8 8 After sorting 2739 79 2 .8 8 35 1 .2 8 Removed 1 .0 8 Before sorting 2771 131 U.7if 57 2 .0 6 After sorting 2590 89 3 .bb 31 1 .2 0 No Filter Before sorting 2835 12b 4.38 82 2 .8 9 After sorting 2818 7b 2 .6 2 b9 1.74 1 ,7 6 Before sorting 2795 128 4 .5 8 69 2.1+7 After sorting 2825 67 2.37 bl 1.1+5 2 .2 1 2 7 .I+ 1+1.7 1+0 ,1 39.8 1+8 .2 1+1.3 1.15 Filter B-23 Removed 3 2 ,0 0 .7 I+ 1.30 Removed 27.3 0 .6 0 Filter B-ll Removed Brown Black 1 .0 2 *Sorting efficiency is defined as 100 percent if all defects are removed. lamps, both from the standpoint of sorting; efficiency ana workers’ choice, further tests wore desirable. Tests at i-hant C The arrangement of the sorting belts end the locations of s&mplin stations are shown in Figure 2b. Incandescent filament lamps -were used on the test toltB. The lighting fixtures wore similar to those at plant B. All the bulbs were changed to now If0 watt bulbs and double sockets wore used to mount twice* as many bulbs in the fixture with the filter. Illumination of three different spectral distributions falling on the belts were as foilows: 1. Skylight varied with the time of day and location on the belt up to If foot-candles. 2. Light from 6 -If0 watt bulbs vailed with location on tho belt xVcjui ft to 130 foot-oardlcs with an average, from 18 readings at selected locations on the belts, of 'jQ foot-candles. 3. Light from 12-lfO watt bulbs covered with filter B-23 produced from If to 37 foot-candles at various loca­ tions on the belts with an average of 26 foot-candles from 18 readings at the same locations as for 2 . (F = 0.5) During the first test light rain was falling and the skylight illumination was very lav;. Additional plant information is as follows: Belt speed: belt "a" 2 0 . feet per minute belt "b" 2 1 .8 feet per minute Belt color: white, but stained tan Lumber of workers: k to 6 (some number on each bolt) Filter B-23 was tested for six five-hour periods. Tho chromatic illumination was used 011 each belt for one-half of each five-hour’ peri During each five-hour test, six samples of approximately ifOO cherries 51 rCO u ouj “to \ ro 2 (E I ^ *UJ o o UJ _) < CJ eriod and resulted in sang)ling a lai0 r batch of cherries. TI10 results of the tests arc: shown in Table VIII. One fire-nour test period was eliminated from the results because tho defects wore so nuroerous that all workers could locate more defects under either Illuminant than they could possibly remove. It might be noted h e m that there are two conditions for which an Improved illuminant would show no Increase in sorting efficiency; namely, when there are so many defects that the workers can see more defects than they can possibly remove, and when tho defects are so few that the workers hove extra time to look for thonext one to pick out. The latter may have been tine for some of the samplesat the previous plant. All samples and the defects counted for each are listed in Appendix II for tho reader’s Inspection. Tho results of the tests compare rather favorably with the theoreti­ cally calculated contrast ratios. For the minor defects there was a decrease in sorting efficiency of i p e r c e n t (not statistically significant) and if we consider the reflectance curve of the under­ color cherry as reprcsentivo of these defects, this contrast ratio is decreased from 1 /2 .5 2 to l/l.93 by use of filter J3-23 (Table XI). For brown defects, the increase in sorting efficiency amounted to 'J.0 percent (not statistically significant) and the contrast ratio increased from l/l .Oh to 1.50/1 for tho filter. Actually the brown defects counted at the plant were a range of browns which in general covered defects 94 TABIE VIII Summary of Test at Plant C Using 150 Watt Filament Type Incandescent Lamps and Filter B-23 as Indicated Minor Defects $ defects in field cherries "before sorting U.3I1 Major Defects Total MaJ or Defects Brown Black By count 6 .6 5 2.48 9.13 By weight 8 .6 1 Sorted under reghlar light $ removed $ sorting efficiency 0 //6 17*7 0.93 14.0 O .7 8 31.4 1 8 .7 1 8 .2 Sorted under filtered light $ removed $ sorting efficiency 0,70 11.1 I.U5 2 1 .8 1.14 46.0 2.59 28.4 2 8 .3 $ removed filtered light minus $ removed, regular light -0 .C6 0.52 0.36 0 .8 8 $ sorting efficiency filtered light minus $ sorting efficiency, regular light -1 .7 7-8 $ improvement in sorting f efficiency using regulaj light as 100 $ 1.71 1.57 2.44 O .87 14.6 9.7 1 0 .1 56 46 51 55 1 .6 5 2 .2 1 2.19 2 .4 7 k *Statistical t-values for samples 1 .1 8 * For statistical significance at the 95 percent confidence interval t= 2.04. 95 much narker than bhr defects used to obtain the ref 1oc bui-Cv cu.7:s f<_a brown. Thus, tho "brown defects for the calculations wore not the same us the range of "brown defects counted at tho plant. The type and percent of "brown defects varied considerably during, the tost. During the first W o five-hour tests the dork brown defects wore rather numerous and the filtered light showed a considerable advantage over the regular light. At other times, especially when mutilated, cherries were prevalent, the regular light seemed to show an advantage. hot enough samples wore obtained to establish this observation. Also, the indication for plant A was negative for filter B-23 where mutilated cherries were noted. This clearly indicates that filter B-23 is poor for perceptibility of mutilated cherries and good for perceptibility of dark brown defects. For the black defects there was an increase in sorting efficiency of It.6 percent (statistically significant at the 95 percent confidence interval) and the contrast ratio was increased by use of tho filter from t.lb/l to 8 .7 2 /1 . Apparently, the results for each type of defect compares well with the calculated contrast ratios. Totals of major defects (i.e. black plus brown defects) are also shown in Table VIII. The increase in sorting efficiency for the totals was 9 .7 percent (statistically significant at the 95 percent confidence interval). The total defects were also obtained by weighing the black and brown defects. the plant. This is the measure used by "U.S.B.A. inspectors at The data shows that the percent of defects are slightly less measured by weight. The difference is probably due to a decrease in weight for defective cherries either from drying or mutilation. The 56 results show an increase in sorting efficiency of 1 0 .1 percent tor the totals by weight (statistically significant at the 91 percent confidence interval). In the final analysis there may he some question as to what measure should he used for illustrating the improvement brought about by use of chromatic illumination, measures given: 1, rieferring to Table VIII there are several the difference in percent of total cherries removed under each illuminant, 2 . and 3 « the difference in sorting efficiency, the improvement in sorting efficiency using the regular illuminant as 100 percent. The first criterion shows how many more defective cherries were removed in percent of total cherries moving across the belt; for example, 0 .8 8 percent of the total cherries (column U). The second shows increase In percept of the defects removed; e.g. 9*7 percent more of the major defects were removed (column. *0 . shews the magnitude of improvement In percent. The third For example, a sorting efficiency of 2 8 .k percent is an improvement of 51 percent over a sorting efficiency of 18*7 percent. A survey of tho workers using the chromatic illuminant yielded the following information; 1, better-5. Did the chromatic illumination bother your eyes? yes-3, no-0, The five who stated that the chromatic illumination was better than the regular illumination stated so without being asked. 2. Can you see the defects better with the chromatic illumination? For black defects: yes-lk, equal-k, no-0 For brewn defects: yes-3> equal-9> no -6 97 3. Do you like the chromatic illumination; yes-11, equal-2, no-1 . from as objective a view as possible, the writer would, omit three of the workers' statements which tended, to disqualify tho chr erratic illuminant on questions 1 and 3 because these workers did not appear to be sincere in their answers, FURTHER A IF lL IF IS OF CHERTSC FOHTIKG Since the field test proved to be statistically significant, it was decided to investigate several additional illuminant-filter combinations in an effort to find a satisfactory combination with higher illuminant efficiency. Such a combination must have at least an equivalent contrast ratio and be psychological acceptable to the workers. -Also, the reflectar. of the sorting belt and its effect on adaptation remains to be discussed. Psychological Reactions to Chromatic Illumination During the field test the workers made definite complaints against the use of red illumination (filter B-.6 7 ). support this finding. The following two accounts Mr. Lloyd Phillips (26 ) of Michigan Fruit Carriers Inc. used pink fluorescent lamps over cherry sorting belts. He stated that the workers on the belt objected to this illuminant even though it did show up the defects better. Also, Mr. R, A, Rice (2 7 ) of the North- port Cherry Factory, Inc. wrote the author as foil owe, "We tried pink fluorescent lighting through red filters on one of our four belts in our Port Clinton Plant. Although this lighting definitely emphasized the defects on the fruit we were forced to discontinue its use because of objections on the part of the ladies working on the belt; they claimed the lighting was hard on their eyes, as it was difficult for their eyes to adjust whenever they looked up from the belt." It appeared, then, that red illumination was definitely unsatisfactory; whether the reason for the workers* complaints was psychological or physiological was not established. The transmittance curves for the filters which registered complaint3 from the workers are shown in Figure 23 - The filter used to produce- red illumination, B- 6 7 , transmits practically no energy at wavelengths shorter than 570 ku. this illuminant. ‘ Hie strongest complaints were leveled against The next illuminant to he eliminated, partially because of workers" complaints, was filter B-7 which transmits the short wave­ lengths of light only slightly. Finally, filter B-ll was eliminated with only one worker's complaint against it. This filter transmits considerably more of the short wavelengths than B-7- No actual complaints were registered against the medium purple filter, B-23 , although four workers stated that they preferred the white illuminant when asked to express an opinion. Figure 26 shows that B-23 transmits almost as well in the blue region of the spectrum as in the red* Although one cannot say definitely, it appears that some illumination from kOO to 500 Mu must be included with strong illumination in the region of 600 to 720 Mu in order for the illuminant to be acceptable to the worker. In an effort to show the appearance of cherries and defects under the different chromatic illuminants, Plate VI is presented. The pictures do not show the true colors and lightnesses because of differences in the spectral response of the eye and the film, and because the adaptation of the eye could not be Included. The pictures were taken by using two photoflood lamps for illumination and placing the filter indicated over the lens of the camera* The increase in contrast does not appear in the pictures nearly as clear as for viewing with each chromatic illuminant however, it is noted that the cherries do appear lighter where the filters were used. The differences in pictures can best be distinguished by 100 100 90 80 ■ 7 < l 60 50 40 30" 20 10 0 ) q 20 40 60 80 5Q0 ^0 WAVELENGTH FIGURE 2 5 . 40 60 IN 80 $ q q 20 40 60 MILLIMICRONS SPECTRAL TRANSMITTANCE FOR GELATINE FILTERS CURVES 80 7QQ 2 101 100 90 70 60 IN PER CENT 80 TRANSMITTANCE 50 40 30 20 10 0 4 q q 20 40 60 80 500 ^0 WAVELENGTH FIGURE 26 . 600 ^ ^ IN ^ MILLIMICRONS SPECTRAL TRANSMITTANCE FOR GELATINE FILTERS CURVES 700 ^ 102 B -7 No Filter B-ll B-23 B -6 7 PLATE VI. Kodachrome Pictures of Cherries and Defects Using Various Spectral Distributions of Illumination. The filter indicated was used over the lens of the camera. From bottom to top: red ripe cherries, light red cherries (not defects), black defects, and a range of brown defects. following one defect through all pictures. The color reflected from the background indicates somewhat the color of the filter. Recognizing the psychological difficulties, additional filters which transmit radiation from 1+00 to 500 Mu were considered. These were filters B-l 8 , B-19, B-20 (Figure 26 and 2 7 ) and four theoretical filters (Table IX and X ) . It appears that these filters should satisfy the requirement of including radiation in the blue portion of the spectrum. However, only filter B-23 has been tested in the field and found to be free of any serious criticism on the part of the workers. Contrast Ratio and Illuminant Efficiency The contrast ratio and the relative luminous flux reflected from the red ripe cherry per watt for the illuminant-fliter combinations, which appear to be psychologically acceptable and those which were rejected, 103 100 90 80 70 60 50 40 30 20 10 0 ) q 20 40 60 8 0 5 Q 0 2-0 WAVELENGTH FIGURE 27. 40 60 IN 80 $ q q 20 40 60 MILLIMICRONS SPECTRAL TRANSMITTANCE FOR GELATINE FILTERS CURVES 80 JQQ 2( 104 TABLE IX Contrast Ratios and Relative Luminous Flux Reflected from Cherries Illuminated hy 2910° IC Tungsten Lamp with Theoretical FiJters Filter A B c D Contrast Ratios Relative Luminous Flux Reflected from Red Ripe Cherries per Watt Range of Wavelengths (inclusive) Mu Brown Defect Black Defect 1+00-500 & 6 0 0 -7 2 0 1 .3 6 /1 9 .3 /1 7l.l 100-500 & 6 1 0 -7 20 1 .5 0 /1 1 1 .0 /1 67.3 1+0 0 -5 0 0 & 6 2 0 -7 20 1 .6 3 /1 1 2 .6 /1 57*7 100-500 & 630-720 1 .7 V 1 1 3 .9 /1 16.2 (wsi; LOn'uiT',3 t Ua 'JS it -vC'IaiLwe; L<.u.;._ioun Flu:; LeTceotel Jfro;.: " i .lCl!-'- ■ Hr C.. ..i.. -A, rPuiLu TL.*orescent vilei-'j.'-l-l./CLLJ—IL',CCxi iv c. ■: . '.•J jLcUij> wj.th The or ctical Filtoi’S Contrast Ratios Filter A B c Range of Wave­ lengths (inclusive) Mu Brown Defect Black Defect 100-500 & 6 0 0 -7 20 1 .2 1 /1 8 .2 /1 170 100-500 & 6 10 -7 20 1 .I0 /1 1 0 .0 /1 ll+7 1.56/1 1 2 .0 /1 115 1 .7 0 /1 1 3 .7 /1 loo-5 0 0 & 6 2 0 -7 2 0 I) Relative Luminous Flux Reflected from Red Ripe Cherries per Watt loo-5 0 0 & 6 3 0 -7 2 0 8 1 .6 are shown in Table IX, 1, XI. at 10 Mu increments. Calculations for these values were made The problem is to obtain a balance between contrast ratio and illuminant efficiency. (Note the illuminant efficiency is measured by luminous flux reflected from the red ripe cherry per watt input to the lamp). From the standpoint of illuminant efficiency and contrast ratio the G. X. deluxe warm white fluorescent lamp with theoretical filters as listed In Table X was the best illuminant-fliter combination found in analysis. For the commercially available filters, Table XI shows that the deluxe warm white fluorescent lamp has the highest efficiency but possesses slightly lower contrast ratios than the 2910 °K tungsten lamp. There are several possible illuminant-filter combinations which might be chosen from this table. Filter B-19 offers an advantage in Illuminant efficiency, especially for the G. E, deluxe warm white fluorescent lamp. On the other hand, B-20 produces a much greater contrast ratio when used with the tungsten lamp but its efficiency is rather low. Thus, Ibr high illuminant efficiency with some increase in contrast ratio the G, E. deluxe warm white fluorescent lamp with filter B-19 may be satisfactory. If a higher contrast ratio Is desired filters B-20 or B-23 with the tungsten lamp would be a better choice. Since no definite decision could be made on the choice of an illuminant filter combination, it was decided to compare the appearance of cherries and defects using filter B -2 3 with both illuminants. A tungsten filament (150 watt bulbs) and a G. E. deluxe warm white fluorescent lamp source were set up in the laboratory. Each was adjusted to provide a level of illumination of 250 foot-candles. samples of cherries were viewed. With filter B-23 over the eyes, It appeared that the cherries possessed lo6 TABLE X I Contrast Ratios and Relative Luminous Flux Reflected from Cherries Illuminated by Fluorescent or Incandescent Lamp ■with Commerical Filters Contrast Ratios** Illuminant Filter* Under-color Defect Brown Defect Black Defect 1 /3 .0 9 1 /3 .0 3 1 /2 .6!* 1 /1 .1*!* 1 /2 .1*6 1 /1 .3 8 1 /1 .01* 1 .0 7 /1 1 .2 U / 1 l/l. 0 l* 1 .0 5 /1 1 .0 1 /1 1 .3 2 /1 2 .5 6 /1 5 .1 1 /1 5 .8 9 /1 1 /1 .1 5 1 .1 1 /1 1 .2 3 /1 3.63/1 6.73/1 7.90/1 6 .5 0 /1 6 .1*3 /1 7 .8 0 /1 6 .9 6 /1 11.3/1 293 196 118 i*.ii*/l 8 .2 0 /1 9.71*/! 8 .2 0 /1 7.90/1 1 0 .0 0 /1 8 .7 2 /1 13.8/1 103 6 7 .0 93.9 2 9 .6 V7.9 2 2 .k 29*7 ¥*.9 Daylight none Fluorescent B- 7 ,Dk.Rose pink B-ll, Med. Magenta B -1 8 ,Med.Lavender B -1 9 ,Dk.Lavender B-20,Light Purple B-23,Med. Purple B -67 ,fire red 1/1.73 1/1.92 1 /2 .2 0 Deluxe none Warm White B-7,Dk.Rose pink Fluorescent B -11, Med.Magenta B-l8 ,Med. Lavender B -19,Dk. Lavender B-20,Light Purple B-23,Med. Purple B -67 ,fire red I/2 .8 5 1 /2 .6 3 1/2.35 1 /1 .7 0 1 /2 .2 2 1 /1 .6 1 I/I .7 8 1/1.95 2910 ° K Tungsten Approx• 190 Watt Filament Type Lamp 1 /2 .5 2 1 /2 .2 7 1 /2 .0 1 l/l. 1*7 1 /1 .8 9 1 /1 .3 8 none B- 7 ,Dk.Rose Pink B-ll,Med .Magenta B-l8 ,Med.Lavender B -1 9 ,Dk.Lavender B-20,Light Purple B-23,Med,Purple B- 6 7 ,fire red Relative Luminous Flux Reflected from Red Ripe Cherries per Watt 1/1.53 1 /1 .7 0 1.33/1 1.19/1 1.1*3/1 1.33/1 '1.1*7/1 1 /1 .0 l* 1.25/1 1.33/1 1 .1*9/1 1 .2 8 /1 1 .6 0 /1 1 .5 0 /1 1 .6 8 /1 l*.03/l 3.93/1 3.51*/l 3.52/1 8 .1 8 /1 211 95.6 6 8 .9 ^9.9 6 5 .0 2 3 .0 35-6 kh.l 50.9 99.6 39.1 9 2 .k 9 0 .0 *Filter numbers are those designated by the manufacturer: Brigham Gelatine Co., Randolph, Vermont. **Calculations were made at 10 Mu Increments. 107 a more luminous character when viewed under the tungsten lamp and the black defects soemed to have a slightly greater contrast with the cherry. Considering both calculated values and observations, the G, 1. deluxe warm white fluorescent lamp is more efficient for producing reflected luminous flux from the red ripe cherries but for equal levels of illumina­ tion the tungsten lamp produces greater contrast ratios for dark defects. Brightness Adaptation Each of the filters, which appear to provide illumination acceptable to the worker, absorb a large part of the radiation from 500 to 600 Mu, This includes the green region of the spectrum where the eye is most sensitive to light (Figure 3)« light in this region. The red ripe cherry reflects very little Thus, eliminating this part of the illumination will decrease the luminous reflectance of the cherry only slightly. If the background reflects energy from 500 to 600 Mu, the filters would reduce the level of adaptation bringing it closer to the desired level which is obtained by uniform field lightness as discussed previously. This lower level of adaptation causes the cherries to appear lighter and should result in improved perception of the cherries. One of the poorest adaptative conditions for sorting dark defects from red ripe cherries is presented by use of a daylight fluorescent lamp with a white belt as a background. amount of the energy of the spectrum. Under these conditions a large from the lamp Is in the blue and green regions With the white background the eye is adapted to a high level of illumination and the relatively small amount of luminous flux reflected from the cherry causes very little visual response. That is, the cherry is dark in appearance and dark defects are difficult to locate. 108 Re rle ctanc c of Ba ckground There are three colors of belt materials used for sorting belts in cherry processing plants; namely, white, tan, and black. Samples of these three materials were obtained and reflectance curves were run on the spectrophotometer (Figure 28). In running these curves it was necessary to use a very wide band width (5 0 Mu). For this reason any sharp deviation in the belt reflectance would not show up in the reflectance curve. However, they should give a good approximation of the belt reflectances. Considering the previously discussed theory and the reflectance curves, the black belt should be the most desirable for sorting dark defects from red tart cherries when using a white illuminant. If the tan, or in particular the white belt, is used with a white illuminant the reflectance from the belt would be much higher than the reflectance from the cherries or defects. This would cause the eyes to be adapted to a high intensity level, as already explained, and would be detrimental when attempting to sort dark defects from cherries. When using an Illuminant with a filter such as B-23, which absorbs much of the energy in the green region of the spectrum, the tan belt appears to be as desirable as the black belt. With this illuminant the eyes would not be adapted to nearly as high an intensity level as with the white illuminant. Thus, It appears that the black belt should be recommended for sorting dark defects from red tart cherries when using white illumination but that the tan belt is satisfactory if much of the radiation in the green region of the spectrum is eliminated. 109 100 REFLECTANCE IN PER CENT WHITE BLACK 400 20 40 60 FIGURE 28. 8 0 ,___ 2 0 40 500 WAVELENGTH 60 80 20 600 IN MILLIMICRONS 40 4 5 °-0 ® SPECTRAL REFLECTANCE FOR CHERRY SORTING BELTS 60 80 CURVES 700 20 110 For sorting under-color chorries or other defects, vhich arc lighter than brown rot7 from, red tart cherries, the reflectance of the hack* ground with white illumination should he betvreen the reflectance of the tan and black belts in order to satisfy the condition of uniform field lightness. There arc a number of Factors which may affect 'the sorting efficiency in fruit processdag infants. include the following: 1, A. list of such factors may rate of inspection, 2. width of sorting holt, 3. direction of approach, b , belt velocity, 5 , 6. rotation of product, movement of hands to discard defective fruit, 7 . (amount, diffuseness, and spectral distribution), 3. illumination reflectance of product and background and, generally, the enviromental conditions. This report discusses the investigation of two factors which were estimated to be very important in present day fruit processing plants. The first is the spectral distribution of the illuminant and reflectance of objects in the field of view. The second concerns the viewing of the entire surface of the product as it passes the workers on sorting belts. Principles of Perceptibility Difference The review of literature and an analysis of lighting for detection of surface differences revealed the following information concerning the optimum visual conditions for perceptibility of color and lightness differences. For maximum perceptibility of color differences. ?. The surfaces should be viewed in proximity. 2. The illuminant should radiate energy throughout the visible spectrum but should be especially rich in the region of the spectrum where the reflectance curves of the objects exhibit the greatest percent should be viewed in proximity. 2. The lightness of the background should epual the lightness of the objects being separated. In this respect a background which is darker than the objects is preferred to a lighter one. 3. The spectral distribution of the illuminant for maximum lightness differences may be found as follows. Multiply at suitable wavelength intervals the luminosity function and the spectral reflectance of each of the objects concerned and plot the resulting curves. Use an illuminant which is especially rich in energy in that region of the spectrum where the resulting curves for W o objects to be separated exhibit the greatest percent difference (See Figure 5)» If the curves for the two objects intersect and cross, the lightness differences may be enhanced by providing an illuminant rich In energy in that region of the spectrum where the curves differ by the greatest percent and by reducing the light in the portion of the spectrum where the curves are reversed in magnitude. Illumination for Cherry Sorting Analysis of perceptibility of cherry defects revealed that the main color difference between red tart cherries and their defects was due to lightness contrast. in the analysis. Thus, only lightness differences were considered The analysis and field tests led to the following statements• A. For sorting dark defects (ranging from brown rot to black) from red tart cherries: .1. The lightness contrast between dark delects and red tart cherries may be Increased by using chromatic illuminants which have strong radiation in the red region of the spectrum (Table XI). 2. For dark defects the 2910° K ir.mgs ten lamp (approximately 150 watt incandescent bulb) produces the greatest lightness contrast of illuminants considered when used without a filter (see Appendix III for illuminants). 3. The G. E. deluxe warm white fluorescent lamp without a filter is the most efficient of lamps considered in producing reflected luminous flux from the cherry surfacej that is, it possesses the highest efficiency when using lightness of the cherry surface as the measure of efficiency. Statements ,,2,, and "3" apply when using certain low-cost gelatine filters over the illuminants (Table XI). 5. For theoretical filters, which perfectly absorb or transmit, the G. E. deluxe warm white fluorescent lamp possesses considerable advantage In illuminant efficiency for the same lightness contrast as obtained with the 2910° K tungsten lamp (Table IX and X ) . 6. Red illumination proved to be unsatisfactory because of worker complaints. Whether these complaints were due to psychological reactions or to physiological effects was not determined. 7. In general, illumination provided by covering the illuminant with a purple filter, B- 2 3 , was favorably I’eceived by the workers. 8. An estimate of a satisfactory illuminant for producing high lightness contrast for dark defects on cherries is aa follows: a. produce at least 180 foot-candles on the belt by use of tungsten lamps or 300 foot-candles by use of G. E. deluxe warm, white fluorescent lamps, and 114 b, cover with filter 3-23* other filters m y also he satisfactory (See section on FURTHER AliALYSIS OF CIDF1SY SOBTHTC-) . From laboratory observations it appears that increasing the illumination beyond these limits will increase somewhat the perceptibility of dark defects. 9. There should be some general illumination in the room although if this illumination is too high it will decrease the lightness contrast and adapt the eyes to a higher level of illumination. An estimate of a satisfactory level of illumination in the plant is approximately 10 foot-candles♦ 10. The most favorable adaptive condition is to have the eye adapted to a field of uniform lightness; i.e. lightness of product, background, and surround should be equal. In this respect a background darker than the product is preferred to a lighter one. 11. Eeflectance curves of the common belting materials used in cherry processing plants shew that the black belt most nearly satisfies the requirement for uniform field lightness for white illumination. However, when filters are used which absorb much of the radiation between 500 and 600 Mu, the tan belt may be as satisfactory. The fruit guards and the workers’ clothing should not have high reflectance and no bright illuminants should be In clear vision of the workers. B. For sorting under-color cherries or other defects which are lighter than brown rot from red tart cherries: 1. The lightness contrast for under-color defects is increased only slightly by changing the spectral distribution of the illuminant. 2. From the standpoint of illuminant efficiency and lightness contrast the daylight fluorescent lamp is the most satisfactory of the illuminants considered. IF ; 3*The reflectance of the backgroundshould be between the of the tan and black belts; therefore, the belt chosen for dark defects (part ,rA") should be k. reflectance acceptable. Fruit guards and workers* clothing should not have high reflectances. 5. An estimate of general illumination for the room would be from 10 to 20 foot-oandles, 6. If the processor desires to remove these light defects, the daylight fluorescent illuminant may be placed at the end of the sorting belt and a partition placed between it and the chromatic illuminant. Sorting Dark Defects from Rod Tomatoes From the 3hape of the reflectance curves for red ripe tomatoes and from observations using filters over the eyes, the statements under numbers 8, 9, 10, and 11 of part "A" for cherry sorting should'apply to sorting dark defects from red tomatoes. Color Grading Tomatoes The illuminant for color grading of tomatoes should possess radia­ tion throughout the visible spectrum. If possible, color of the back­ ground should be the average color of the product. For grading tomatoes into four grades (green, pink, dark pink, and red) no additional recom­ mendations were indicated by the analysis. For grading tomatoes into light red and dark red, as in Michigan canning plants, it appears that the illuminant should possess radiation throughout the visible spectrum but should be especially rich in energy from approximately 580 to $+0 Mu. Further research is needed on this point before definite recommendations can be made. Viewing the Entire Surface of t-ie Product The literature shows that viewing the entire surface of the product is essential to high sorting efficiency. Since rotation of fruit brings most of its surface into view, two devices were developed and tested for rotating cherries as they move along the sorting belt. These were a small, smooth, stationary rod mounted across the belt and a friction-coated rod which rotated to lift the cherries over it. The merits and application features of these devices are listed as follows: 1. The stationary rod must be mounted closely against the belt in order to prevent cherries from being caught underneath it. On most sorting belts it appears necessary to support the belt underneath the rod in order to insure contact. 2. The stationary rod had the disadvantage of interferringwith the passage of the belt lacing. It may be necessary to provide endless belts if this device is employed. l. The maximum efficiency obtained with the stationary rod was approximately 55 percent of the cherries rotated 90 ° or ^ore and lt-5 percent rotated 150° or more. The efficiency of this device decreases as the belt velocity increases and as the percent of the belt covered with fruit increases. U. The efficiency of the rotating rod may reach 80 percent of the cherries rotated 90° or more and 60 percent rotated 150° or more. efficiencies were obtained with the belt completely covered with cherries. 5, The rotating rod requires a driving mechanism, 6. The rotating rod was mounted approximately l/l6inch above These the sorting belt. It clicl not interior • vlth it \ the tests. 7. With a coating of black friction tape on the rotating rod, the maximum efficiency for rotating cherries was reached when the peripheral velocity of the rod was about twice the belt velocity. 8. belt. These devices might be located between the workers along the With this arrangement earn successive worker would see many different cherry surfaces. In addition to rotating the cherries these devices have some, beneficial effect in spreading the cherries across the sorting belt. The literature provided the following statements; 1. Products, which are rotated continuously as they move along the belt, should rotate so that the top surface of the product moves in the same direction as the belt (forward rotation); otherwise, the workers may develop nausea at certain critical belt and rotational speeds. 2. For continous rotation, the product should rotate at least 3/t of a revolution per foot of translation. 3. Smooth continous flow of the product Is preferred to irregular flow and haphazard spacing. Other Factors 1. Black and brown defective spots on cherries do not fluoresce when exposed to radiation of a high pressure mercury vapor lamp which possesses a group of spectral lines near 365 ^ll* 2. It appears that cherries may be sorted by transmitted light. However, the intensity of Illumination required is rather high. 3. bpecular gloss from cherries may bo minimized by using dif illumination. This should improve perception and bo easier on the APPENDIX I REFLECTANCE CURVES All reflectance curves for cherries, tomatoes, and belt samples were run with a Cenco-Sheard spectrophotometer at the Michigan State Highway Departments Research Laboratory. A picture illustrating the use of the spectrophotometer and the arrangement is presented in Plate VII. The sample and a reflectance standard were mounted on a disk •which could be rotated and were illuminated with an airplane landing lamp at an angle of incidence of 1+5 degrees with the surface of the standard. The entrance slit of the spectrophotometer was positioned at zero degrees to the surface of the standard (perpendicular viewing). This arrangement avoids the main beam of specularly reflected light by 1+5 degrees and is recommended for use when visual appearance is the main objective (28). The reflectance standard and the samples were PLATE VTI. Kodachrome Picture of Spectrophotometer. The sample and the white reflectance standard in the background were rotated alternately Into viewing position to take readings. ii. c _ L e i * The standard of comparison (reflectance standard) consisted of \ magnesium oxide sim.-ncd on an aluminum plate, A fresh standard vac prepared for each set of curves by collecting the smoke from burning magnesium. ribbon in air. This standard is used almost universally as a color standard for spectrophotometryc work (20)* When the magnesium oxide is freshly prepared, its reflectance varies lees than one percent throughout the visible spectrum and its total reflectance in the visible range is 97 to S'O percent (2Q) . The apparent reflectance of this standard, when illuminated, at degrees and viewed at the normal, has been adopted by the Interration Commission on Illumination an I.00 (29). The band width used for reflectance curves was 12.9 Mu or less except for curves of the sorting belts, In this case it was necessary to use 90 Mu band, width due to lack of sensitivity of the available galvanometer. Thus, any sharp deviations in the reflectance curves for the belts would not be shown. However, they should represent a fair approximation for the purpose served. After running curves for Florida tomatoes, the wavelength scale of the spectrophotometer was calibrated and a correction made for the scale readings. Different corrections were necessary for the wavelength scale readings after making adjustments. Appropriate corrections for the scale readings before and after calibration are shown in Table XI]. With the wavelength scale corrected and using the magnesium oxide standard with recommended angular conditions, the only other major source of error appeared to be the specularly reflected light from the in TABLE XII Corrections Tor Wavelength Scale of Cenco -Sheard Spectrophotometer Scale Heading Mu i+oo 10 20 30 1+0 50 6o 70 80 90 500 10 20 30 1+0 50 6o 70 80 90 600 10 20 30 1+0 50 6o 70 80 90 700 10 20 Corrected Wavelength for Plotting Before Calibration* Mu 392 1+02 M3 1+23 ^33* 1+1+1+ 1+5 I+ 1+61+ 1+75 1+85 ^95 506 516 526 537 5i+7 557 568 578 588 599 609 619 630 6i+o 650 661 671 681 692 702 712 723 Corrected Wavelength for Plotting After Calibration Mu 396 1+06 1+16 1+27 1+37 1+1+7 i+58 1+68 1+78 1+89 1+99 50'9 520 530 51+0 551 561 571 582 592 602 613 623 633 6I+1+ 651+ 661+ 675 685 695 706 716 726 * This column applies only to the reflectance curves for Florida Tomatoes. 122 outside curved surface of the fxuit. however, since specularly reflected light is directly proportional to the spectral distribution of the xlliiuiiriont (i.e. non-selective reflection) , it is possible tc estimate the maximum specularly reflected light, especially if the reflectance curves have very low reflectance in some region of the spectrum. For the cherry curves given in the following pages it is noted that several of the red ripe cherry curves possess as little as one percent reflectance from tOO to 500 Mu, Therefore, it appears that the specularly reflected light should be less than 1 percent for this region of the spectrum and should not exceed 2 or 3 percent for the longer wavelengths of light where the intensity of the incandescent illuminant is considerably greater. For the tomato curves, however, it appears that the specularly reflected light was much greater. An estimate would be in the vicinity of 5 to 10 percent for the short wavelengths with a maximum of If to 20 percent for long wavelengths. It was noted that rotation of the sample sometimes changed the reflectance of a sample as much as > percent. The reflectance curve of cherry sample 5 (black defect) Increased slightly from 620 to 720 Mu. This increase was attributed to a small edge of red which projected from the side of the cherry; thus, the slight increase in reflectance from 620 to 720 Mu was neglected and the curve was drawn straight at one percent for the red region of the spectrum (Figure 33)• 123 50 30 REFLECTANCE IN PER CENT 40 20 400 600 500 WAVELENGTH FIGURE 29. 4 5 °-0 ° FOR RED RIPE IN MILLIMICRONS SPECTRAL REFLECTANCE CURVE EARLY RICHMOND CHERRIES 700 20 12k 50 30 REFLECTANCE IN PER CENT 40 20 WAVELENGTH FIGURE 700 600 500 IN MILLIMICRONS 30. 4 5 °-0 ° SPECTRAL REFLECTANCE FOR RED RIPE SCHMIDT CHERRIES CURVE 20 125 50 30 REFLECTANCE IN PER CENT 40 20 500 400 WAVELENGTH FIGURE 31. FOR 600 IN MILLIMICRONS 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE LIGHT COLORED SCHMIDT CHERRIES 700 20 126 50 30 REFLECTANCE IN PER CENT 40 20 400 20 40 60 80 600 500 WAVELENGTH IN MILLIMICRONS FIGURE 3 2 . 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE FOR BROWN DEFECTIVE SCHMIDT CHERRIES 700 20 127 50 'I -1 - 4 f -t - f 4~ 4— T 40 - 4- • -4---------- ~-1 4- REFLECTANCE -r l- 1!- ! 30 — j— i- - nH IN PER CENT .— 4 r H 4 4- 4 L I- ; hi 20 h j ! ! t| I ! I 4-- L-1 -1.--4. 1 _. _! +_ 1— — t- ■4— r _ i _ t • I10 _| -\ ..__4 ---- ^ I- H ’ 1-4 1 - 4 4 _4— i-- r x> ..rfl ■tr 400 20 40 60 FIGURE 3 3 . FOR 80 20 40 500 WAVELENGTH J 60 80 20 40 600 IN MILLIMICRONS L 60 80 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE BLACK DEFECTIVE . SCHMIDT CHERRIES 700 20 128 50 30 REFLECTANCE IN PER CENT 40 20 400 600 500 WAVELENGTH IN MILLIMICRONS FIGURE 3 4 . 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE FOR BROWN DEFECTIVE MONTMORENCY CHERRIES 700 20 VIII REFLECTANCE IN PER CENT PLATE n 400 20 40 60 80 500 20 40 WAVELENGTH FIGURE 35. FOR 60 IN 80 600 20 40 60 80 MILLIMICRONS 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE UNDER-COLOR MONTMORENCY CHERRIES _ 20 700 139 50 r REFLECTANCE — !p PL.ATE X ■ i 1 i i . 30 ! \ IN PER CENT 40 ! ■ i i 20 \ ! ._ _ _ 1 ill| i "" .. . f11 }1 " i 0 ■■ ■ . I i ! i ; •. + - j _ 11 _ J. J _ i -f- -- ;11 *■•■■■" - I1ii P - -_ ._ i—O'r ] /**» j© " " V I 400 20 40 .. _ -L - !- !j P r i . , ’ 1 ' i I f .. !■ [ ! 1 ! 1 t~■ 1 j ; V1 1 ' i r ; ; f : J ' !i 1 I n J !... i J . / ! __ i : / .....— • -■ d • ... - j : . ....... . -4-11 ' J i 4 " -1 Ti j : . ! Ii - -J ' !1 !i 1 _ ij- .— p--j h -ti-.I 1_ f: ' '. ! ~T j_ 1_ J zj r ; L.i8. LJ L — -1 ; j L__ L... i ! ir «: 1 i ~j J j i_ ;_ IiI } 1 ' 1 I L._ Ii 1 / P | -1i . ji1_ _ L-i/J i-..r -|r _p P 1_ I-- 1|-. 'h L i _J jr__ j _ 1!_ _.J.. .. r~4 f \__ ; )..... .J-_. . 7” .1 i |_ _ 1 — i!‘ 1 .1 ■1:_ J ij_ _ ,/ r P I ■'i l :l :.. . i J _ 1 j_ j __ 1 + . j . J IjP| P y .. 1 _a |_ i_ , [— L~_ V7 •*- j L_ — O ■ ■*1r" j c 6 0 80 20 40 WAVELENGTH 1 , — ■ i i— ..... i ... — • i— ' ji i -.— J V 500 1_ i P 60 IN 80 600 20 40 60 80 MILLIMICRONS FIGURE 3 6 . 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE FOR RED RIPE MONTMORENCY CHERRIES 700 20 CENT 131 REFLECTANCE IN PER t- PLATE -L C> fi 400 20 40 60 80 500 20 40 WAVELENGTH 60. IN 80 „ __ 600 20 40 60 80 MILLIMICRONS FIGURE 37. 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE FOR BROWN DEFECTIVE MONTMORENCY CHERRIES 700 20 REFLECTANCE IN PER CENT 132 400 20 40 60 80 500 20 40 WAVELENGTH FIGURE 3 8 . 60 IN 80 600 20 40 60 80 MILLIMICRONS 4 5 ° -0 ® SPECTRAL REFLECTANCE CURVE FOR RED RIPE MONTMORENCY CHERRIES 700 20 133 90 80 70 60 50 40 30 20 10 a o I I ; 1 i 1 : _J 20 40 60 80 500 1 ---- --- 1—. —i --- 1 1 ----- --- 1 : 1 20 40 WAVELENGTH 60 IN 8 0 ____ 2 0 600 40 —— 60 80 MILLIMICRONS FIGURE 39. 4 5 ° - 0 ° SPECTRAL REFLECTANCE CURVES FOR RED RIPE FLORIDA GROWN TOMATOES — 700 20 13k 90 80 70 60 50 40 30 20 A 10 o 0 | —l 1 20 40 - J-- 1__ 60 80 1-- 1-- 1------ ^ -- 1------ ___ 2 0 500 40 WAVELENGTH FIGURE 40. FOR 60 IN 80 *--^ -- 1-- 600 20 40 *-- 1--J --- 60 80 MILLIMICRONS 4 5 °-0 ° SPECTRAL REFLECTANCE CURVES PINK * FLORIDA GROWN TOMATOES 135 100 90 80 60 IN PER CENT 70 REFLECTANCE 50 40 30 20 A 10 0 *— 400 20 40 60 80 500 20 40 WAVELENGTH FIGURE 41. 4 5 ° - 0° FOR GREEN 60 IN 80 600 20 40 60 80 MILLIMICRONS SPECTRAL FLORIOA REFLECTANCE GROWN CURVES TOMATOES 700 20 136 REFLECTANCE IN PER CENT 100 _ 400 20 40 60 8 0 ___ 500 20 40 WAVELENGTH 60 IN 80 600 20 40 60 80 MILLIMICRONS FIGURE 4 2 . 4 5 °-0 ° SPECTRAL REFLECTANCE CURVES FOR LIG H T RED MICHIGAN GROWN TOMATOES 700 20 137 100 90 80 60 IN PER CENT 70 REFLECTANCE 50 40 30 20 400 500 600 WAVELENGTH FIGURE 43. 4 5 °-0 ° FOR RED RIPE IN MILLIMICRONS SPECTRAL MICHIGAN REFLECTANCE CURVES GROWN TOMATOES 700 20 138 too 90 80 60 in per cent 70 •r e f l e c t a n c e 50 40 30 20 600 500 400 WAVELENGTH FIGURE IN MILLIMICRONS 44. 4 5 °-0 ° SPECTRAL REFLECTANCE CURVE FOR GREEN M ICHIGAN GROWN TOMATO 20 APHEIKEDC ll FIELD TEGT LATA This section gives a list of samples and the number of defects counted for each sample in the chromatic illumination tents, at three cherry processing plants. The samples given on one continous line were taken from the same batch of cherries as described in the field test procedure. TABLE XIII List of Samples and. Defects Counted for CUromatic Illumination Tests at Plant A* Before Sorting Total 373 1+02 1+22 i+ot 1+16 388 393 382 Total 318 o °jo defec' Brown Filter B-7 Black 11 21 21 17 23 13 ll+ 16 136 1+.28 Total Brown Tp 7 2 21+ 9 13 8 16 377 371 389 365 368 370 382 355 1+ 10 6 91+ 2977 2.99 383 397 1+09 391 1+09 3*+9 Total 2698 119 io defec is 1+.1+8 1+00 1+16 ll+ 8 13 9 3 67 2 ,2 9 63 3183 2 .1 2 Brcwn 7 16 11 13 12 31 9 389 37^ 381 393 377 1+00 3^8 2 1 VJ!g 10 16 20 10 21+ 18 21 r O Total 9 1+ 10 9 7 7 11 Total 2698 Black —r*o3 388 Brown Black 1+03 399 391 391 1+00 387 Brown ll+ 6 9 ll+ 6 8 1+ 12 Black 9 9 0 3 9 10 7 7 69 91 2.16 1 .6 0 Bo Filter Filter B-ll Before Sorting Total lio Filter Black 6 Total 7 1+ 13 11 13 10 2 1 12 3 398 3^1 383 376 390 388 3I+0 91 1 .92- 1+1 2976 7 1.9^ Brown Black S' 7 9 20 12 ll+ 20 16 0 1+ 12 0 91+ 3 .6 5 90 1.9^ (Continued) 9 9 10 TABLE XIII (cont’d) List of Samples and Defects Counted for Chromatic Illumination Tests at Plant A* Before Sorting Total 368 375 389 3^8 372 392 379 Filter B-2 3 Brown Black Total Brown Black 3^ 39 10 11 13 19 12 9 if 10 18 10 15 13 411 396 369 37^ 380 382 368 35 30 8 17 12 lif 6 3 0 11 if 11 6 5 399 390 if25 397 399 ifllf 397 19 19 7 8 8 13 3 10 Uo l.if9 2821 77 2 .7 2 65 2 .3 0 Total 2623 138 % defect 3 5.25 79 3 .0 1 Before Sorting Total if05 ififif if32 372 M3 330 335 327 Brown 15 21 23 13 28 12 12 lif Total 3058 “^defects Uo Filter 138 2680 122 M 5 Total Filter B~6t Black Total 15 15 12 9 5 8 18 9 395 if25 ifl7 373 395 358 356 3^5 91 2 .Q8 3069 Brown 6 5 6 10 19 6 7 5 a 2 ,0 8 .„ Brown Black If 9 13 16 7 6 Bo Filter Black Total Brown Black 7 1 7 3 7 5 if 5 if02 382 M3 381 365 31 k 321 351* 17 5 18 12 18 5 10 if 9 3 if 8 12 5 6 if 39 1.27 2932 89 51 1 .7 2 * The source for chromatic illumination consisted of G. E. deluxe warm white fluorescent tuhes and the filter as indicated. Three tubes were used side by side (12 tubes total in fixture). For the comparison source a single tube fixture, (if tubes total in fixture) containing G. E. deluxe warm white fluorescent tubes, was used. Four standard cool white fluorescent tubes were used regularly on belts. § A) M Ph o . 4 o v o i—! ON ON t“- CO r-j ^ o LfN ro VO r-H o LTN 0 0 CM IT \ i r \ t — CO r-H CO H i—| H r-l ON t~ -4- LfN H LfN ON ITN CM -di—1 i—1 i—I i—1 i—1 i—1 i—! LfN O rH O 0 0 r-H tfN G \ H H - d CO f — [— CO H OO O CM cooooocooooooooo ON CO t— CM ON O t — LfN LT\ O ON CM .d- 0 0 LfN-d- CM COCO CO c o o o c n o o c o c o c M CM c— LfN VO CM 4 rH s * CM % § o pq O o-i SP Jh o 0 VO UN * oo pq u © -P H O u © -p IfN ON CO LfN CO CO rH -M" . 4 - 4 OQ - 4 OJ -4 * VO VO oocococococococo CM ia 3o EH © u o © pq co < —I 00 O IfN CM LfN CO ON CO CO ON- 4 IfN LfN CO LfN-4" LfN oocooorocoporoco IfN CO 00 CM LfN -4 u © +5 LfN CM -4" CM VO - 4 0 0 O rH -4 $ M o ‘ —I pq © o © tfN CM CM - 4 0 0 - 4 VO CO U © •P CM rH O - 4 rH r-| rH C— CO VO ON L-— i —1i —IrH rH On vo r CM pq t— vo t — CO CM •H 4-1 GQ % CO CM >,0 I pq u pq I S o © « LfN O LfN IfN - 4 t - - - 4 O N - 4 rH I—I CM rH rH rH CM CO CM rH © pq -P i—©| {= U © -P 3 O LfN ON LfNLfN CO CM v g CO IfN C— VO CM UN UN v o co co co co oo m co co Jh o © pq O ON H UNCO tV-C Q [H CM - 4 VO CO CO CO VO CO co co co to co co ro co UN CM CO CM UN ON t- CM © s © _£l $ O EH P a o rd © © 3 TABLE XV List of Samples and Defects Counted for Chromatic Illumination Tests at Plant C* Before Sorting Filter B-23 No Filter Total Minor Brown Black Total Minor Brown Black Totalj Minor Brown Black — ~— 1+31 it-12 1+01 1+36 1+49 1+1+1+ ■XrXrX 27 2 l+ 21 22 13 1+ 5 15 398 393 393 1+76 378 395 1+12 1+01 3 16 6 6 393 31 1+7 1+3 26 31 27 U 3I+ 1+31 395 1+05 I+I3 1+31+ 21+ 15 16 31 20 31 l6 27 11 7 19 21+ 10 1+ 6 1+30 1+25 1+22 7 6 8 1+00 1+1+8 385 367 25 21 19 16 11 18 21+ 13 7 19 16 12 12 396 39h 1+01+ 1+18 1+08 33 13 8 16 16 12 12 62 1+9 25 11 1+11+ 15 1+0 79 1+1+ 17 12 7 18 30 26 351+ 1+17 1+09 1+23 1+1+1 279 1+2 8 12 1+28 1+59 12 20 1+71+ 1+51+ 1+7 U 1+20 3 9 10 7 31 39 1+1+ 38 13 lo 11+ 17 k09 hok 1+25 ^35 i+6 i+ 1+28 333 1+7 !+ i+23 I+27 1+1+1+ 31b 1+71+ 23 20 15 ik 32 29 29 17 32 35 1+17 1+25 ^55 i+6 l 1+1+3 500 1+37 x-x-x- 381 1+02 x-x-x- 20 1+19 30 32 36 32 19 31 33 20 23 ll+ 17 13 15 27 35 22 35 15 13 12 13 7 9 13 26 , 7 3 1 5 5 3 0 12 17 16 11 13 7 31 13 17 11 11 16 19 5 2 2 1+ 1+ 1+ 1+17 399 1+21+ 1+51 23 17 21 20 7 2 22 22 7 1+ 15 8 8 9 397 377 387 385 1+17 1+60 18 12 25 8 6 8 10 20 6 52 36 17 25 1+2 68 1+0 5 5 6 1+12 25 11 30 20 9 9 10 7 10 7 25 37 17 13 20 li+ 29 38 33 7 6 27 18 5 5 3 5 6 12 1+1+2 1+1+1+ 1+10 1+17 1+32 1+37 1+1+2 358 1+68 1+32 1+21 1+38 281+ 1+60 1+79 509 1+35 1+52 1+22 26 9 20 10 9 28 17 16 lk 15 5 9 10 6 10 7 6 10 1+ 6 1+ 16 8 8 5 8 6 1+ 6 2 8 10 8 15 8 21+ 3 3 1+ 7 1+ 28 6 23 28 31 20 15 5 16 17 1+ 8 53 33 10 27 50 1+6 38 5 6 6 11 19 29 15 27 26 29 9 2 6 11 1+ 9 29 28 26 (Continued) TABLE XV (cont’d) List of Samples and Defects Counted for Chromatic Illumination Tests at Plant C* Before Sorting Filter B -2 3 Total Minor Brown Black Total 1+70 11 12 1+1+8 55 430 10 11 1+30 37 6 12 1+19 1+11 29 6 2+12 395 9 1+7 8 1+2 18 1+39 1+37 1+28 I+27 1+0 10 9 No Filter Minor Browx Black Total 29 1+38 15 9 12 27 1+17 5 1+ 26 8 1+09 1+8 10 1+13 5 6 1+6 10 ^53 1+ 36 1+51 7 Minoi Browi] Black 13 8 10 12 1+ _> 36 37 33 30 i+3 51+ 12 12 9 r7 i 9 8 TotaJ s and Percen t Defe ctive 16563 669 ' 1226 1+.25 7.2+1 l+6 l 16299 2 .7 8 51+7 3.52 982 6 .0 2 161+91 255 1.57 537 1039 3 .1+1 6.32 3^3, 1 .9 6 Total s and Percer t Defc ctive (exclu ding Qest IV )** 13720 912 599 u. 32+ 6 .6 5 32+0 2 .1+8 13503 1+61+ 3 .6h 702 181 5.20 1.3*+ 1367 ^ i+6 i 3*58 782 5.72 232 1 .7 0 * The source for chromatic illumination consisted of 150 Watt filament type incandescent lamps; twelve lamps, covered with filter B-23, were used for the entire belt. The comparison illurainant consisted of six 150 Watt lamps for the entire belt. **Test IV was eliminated from the test data because the number of defects was excessive* All workers could locate more defects under either illuminant than they could remove. ***Minor defects were not counted for the first two sample-3 . atd TU11G3TEL FILAM&I.T LAltbG This section gives in tabular form the spectral distribution cf the G. E. daylight fluorescent, G. E, deluxe warm vhite fluorescent, and th 29-10° K tungsten filament lamps. The same designation for Iliuminants of other manufacturers may not have the same spectral distribution* Also the spectral distribution of lamps manufactured in the future may be altered. The values presented here were obtained from the Nela Park laboratory of the General Electric Company in 1955* TAD I E X V I Spectral Distribution of G. E. .olucrescunt are Tungsten Filament LampsM Wavelength Microwatts per 10 Mu per Lumen Mu Fay!ight Fluorescent 1*00 129.0 10 20 30 9b. 3 22.5 67.7 6 6 .7 9.9 1 2 .3 it.0 299.3 1 9 .0 2 0 .6 27.5 32.5 37.5 ^3.5 50.0 97.0 63.5 70.5 78.5 102.9 ho 315.1 50 60 70 80 90 900 130.0 138.8 10 20 30 1*0 90 60 70 80 90 600 10 20 30 1*0 90 60 70 80 90 700 10 20 Deluxe Warm White Fluorescent 11* 0.8 22.3 ll+G o 135.1 127.9 28.7 27.3 39.6 119.2 61* 1 1 2 ,1 107.2 106.2 222.2 1th.1. 196.0 189.0 193.9 137.7 107.1 95.t 71.3 98.5 15*5 39.2 2 6 .6 19.8 It .6 11.9 9.0 8.0 .2 29i0o K Tungsten Filament Lamp** 86.0 9 2 .2 91.5 102.0 100.0 100.5 217.0 llt.O 119.5 130.7 187.0 183.0 2Cl .0 208.0 199.0 181.0 195.7 128.0 100.5 78.7 59-2 1*1*.7 31.2 22.1 16.0 111.0 129.0 137.5 11*6.0 1 5 1 .5 163 .0 172.0 180.5 189.0 197.5 205.0 212.5 220.0 227.5 ^jj •5 2 tC .0 21*7.0 8 5 2 .5 C r. * Tolerance of manufacture may be as high as plus or minus five percent ** Values in this column were read from Bpectral distribution curve for tungsten filament lamps. APPENDED REFERENCES •.i., U.S.D.A. Standard a for Graflea of Cammed. Sod Sour (Tart) fitted Che m i e n . Trod net ion ana Mar tooting Administration. 5 th issue. Juno 23 , 19^?. 2 . Nickerson, p. "Color Measurement and Its Application to the Grading of Agricultural Products." A llandlock on the Method of Dish Colorimetry. Misc. Puh. 98c. U.S.P. A. March 19^6. 3. Michigan Agricultural Statistics. May 1993. Michigan Denartment of Agriculture The Science of Co'or. Committee on Colorimetry, Optical Society of America. T, Y. Crowell Co. New York. pn. 67 ,6 9 -173 ,2 2 0 253,376. 1953. 5 . Peterson, G, M. The Effects of Color Environment on Grading Efficiency in Food Processing Plants. Unpublished M. S. Thesis. Michigan State College. 1951. 78 numb, loaves. 6 . Famham, E. E. and E. A. Linsday. "Colored Lighting for Color Printing". Nela Park, Cleveland, Ohio. Bulletin LS-122 I9 U9 . General Electric 7* White, D. "Maximizing Color Differences.” Ph. D. Thesis in Electrical Engineering, Stanford University, 1950. 122 numb. leaves, 8. Nickerson, D, "The Illuminant in Color Matching and Discrimination." Illuminating Engineering. v. 36 , pp. 373-399* 19^1- 9- Taylor, A. II. "The Nature and Causes of Small Color Differences In Industry; Lighting for Their Detection," £. of Opt. Soc. of America, v. 3 2 , no. 11, pp. 65 1-6 5 8 . November 19^2* 10, Judd, D, D. Oral Communication. June 25, 1953* 11. Malcolm, D, G. and E. P. DeGarmo. Visual Inspection of Products for Surface Characteristics in Grading Operations. IJ.G.D.A., Production and Marketing Administration. Marketing Research Deport- No. bf. Washington, D. 0 . June 195''O 12, Rossi, A. "Some Effects of Direction, Speed, and Size in the Visual Inspection of Cylindrical Surfaces." Unpublished Masters Thesis, University of California. September 1951-. (.After Ref. 11). lo. DeHart, A. {,. "Inspection of Cylindrical Lurfacoo in Comhired Translation and dotation." Unpublished Masters Thesis, University of California. July 1950. (.S Lor P.of. 11). ^3+. Evans, 1. j’. "Psychological repeats Color and Illumind U Illu:;iinoting Engineertng, v. kG, px . 176-l3l. April 199'. 15. Evans, P. ii. In Introduction to Co Cor. John Wiley and Cons, Lew York. pp. 95-137j 1!>V. lp+B, o 16 . Bartley, E. II, f VI aion, P. Van Lostrand Company, 19*+!* 17. Judd, D. B. Co1or in Business , Sc ionc c } and Industry. Wiley and Cons, Inc. how York.' pp. 11^30, ~T3b-131, 2k9. 18. Ruch, F. L. Psychology and Life. and C ompany". 19*+S . 19. Wald, George. "Molecular Basis of Visual Excitation." Sciontist. v. *+2, pp. 73-9' . January 1951• 20. Helson, Harry. "Fundamental Problems in Color Vision. 1. The Principle Governing Changes in Hue, Saturation, Lightness of Non-Celective Camples in Chromatic Illumination." Journal of Experimental Psychology, v. 23, pp. *+39-*+76« 1938 . 21. Helson, II. and V, B. Jeffers. "Fundamental Problems in Color Vision. II. Hue, Lightness, and Saturation of Selective Samples in Chromatic Illumination." Journal of Experimental Psychology, v. 26, pp. 1-27 . 19t0 . 22. Illuminating Engineering Socle521 Lighting Handbook. 2nd Edition, Illuminating Engineering Society, hew York. 19 23. Bartley, S. H. "The Comparative Distribution of Light In the Stimulus and on the Retina." Journal of Comparative Psychology, v. 19, pp. 149-15^. 1 9 3 5 . 2b. Adams, E. Q. and P. W. Cobb. "The Effect on Foveal Vision of Bright (and Dark) Surrounds." Journal of Experimental Psychology. v. 5, 39EE* 1 9 2 2 . 25. Fundamentals of Light and Lighting. Lamp Department, General Electric Company, Bulletin ID-2, Third printing. February 1950. 26. Phillips, L. 27. Rice, R. A. Oral Communication. Written Communication. 3^d Edition. 1952. Scott, foresman July 2k, 1953. January 5, 195*+. lonerican Judd I), B . Colorimetry. Rational Bureau of Standards Circular 478. March 1950. Preparation and Colorimetric Prox>ortics of a Magneelim-Qxlde Ref1ectancc Standard. IJ. S* Department of Commerce National Bureau of Standards. Letter Cir; LC-5*+7. Superseding LC-3 March 17, 1935* 17717]-pi-i i-rpTjiyprjjp7r/^t;^* Beclcer, C. and \J. ', Appc1 . "Evciluation of Man 11a-Rope Fib or for Color", R , ■'. Department of Commerce, Bureau of ft.andp.rd3, Research lapor EP627. Part of Bureau of standards Journal of Research, v. I.1. Beceruber 191°. o Bentley, C . P. "Industrial Tristiimilus Color Matcher." v. 2b, no. 8, pp. 102-f, August 19^1. Electronics. Brarity V,, K. II. Norris, and G. Chin. "A Spectrophotomctrie Method for DetectingBlood in White-.Shell Eggs". Poultry 9cienco. v. ^2 , no. 2 . March 1953* k. Davidson, P. P, "Visual Sensitivity to Surface Color Differences", Ont. foe. Am. v. bl,xjp, 104-11. February 1951* de Vries, U. "Basic Sensation Curves of the Three-Color Theory." Opt. Son. fuu. -I. v. 26, pp. 121-7* larch 1946, 6. ISvans, ”, M. "LightSources and Colored Objects." Eng.A.? orlng. v. 44, p p .47-5-A January I9*f3* i* r> ■j * o Illuml'int Ln Finn, J. F, "Inspection Lighting for the Dry Clean! .t-ijU, JLllCLviG III iunl.ua tliig Engineering. April 19^9* * Gnth, 'A A. "Comfortable Brightness Helationships for Critical and Casual Seeing," 11.1umina 11ng Engineering, v. bo, pp . 9 L-lruury 19^ Hardy, 1. II. "The Bases of Color Vision." v .p ■ one -mo Tnh i ;6, m>- 5 9 5 -31 2 . 19^ 1 . IIJ.iurAnating ira 10 . Heclit, :A "Tlie Development of Thomas Young As Theory or Color Vision.'’ Jour. Opt. See. Am. v. 20, 231ff. 1930. Helmholtz, H. V or. "A Treatise on Physiological Optics." Opt, 01 jiioin.;a. fraxislated xx’oui Tli.trd mu • Eciited oy J ,, , , 77 ~ 192 ^. ^2 . Helson, Harry. "Color Tolerances as Affected by Changes in Cornicesition and Intensity of I.llumlnation and Reflectance of Background." The American Journal of Psychology, v. 32, pp. 4o6-4l2. Iflf. Helson, II. and D. B. Judd, "An Exper 1me11ta1 and Tlieoretical Study of Changca in Curface Colors Under Changing Illuminations." Psychological Bulletin, v. 33, p. 7 8 0 . 1 9 3 6 . Ih. helson, L. aal W. 1. Mich,.; j. j ! j ■,(' a r o m a t a c j. r < y , 1 J . \ g a ’’The Irfccbs of Chromatic ■L e . '. a . v , ',8 ' 1 ' 2 t _ :' - — C L . "* / ‘t- 1;- * Hunter, 1. C. 'Lticboeiectric Trig iianlus Colorimetry vi bh Tht-c l j.l'boi'o . -iLi’eular of the national Bureer cf Ctand'U'd -4S'".. "~ly Z' j 1941. lo. Hunter, C. "The Basis of Color Iieaeurement," .1 i^apor pro sou tod at tlie First Annual Meeting of the Technical Association of the Lithographic Industry. Chicago, 111, April If, 19'Co 17- Hunter, L. "A "Gloss Evaluation of Materials." Mo. loo. December 1952. 18. Judd, P. 13. "The 1931 I* ('• I. Stu.lLard Observer and Coordinate System for Colorimetry." Jour. Opt. Soc. Am. v. 23 3 pp. 359374, 1933* If. Judd, J). B. "Specification of Color Tolerances at the national Bureau of Standards." Am. Jour, of Psychology, v, 5 2 , pp. 4l8420. 1939. 20. Judd, L. B. "Hue, Saturation and Lightness of Surface Colors with Chromatic Illumination," J, Opt. Soc. Am. v* 30, pp. 2-32. 1940. 21. Judd, 1, L. 22. Kramer, Amihud. "This Meter Gives Better Color Evaluation." Food Industries, v. 22, pp. 1897-1900. 195l» (copyrighted 1951 t>y McGraw-Hill Publishing Co., Inc. New York 18, 1. Y.) 23. Larson, L. c. "Illumination of a Laboratory Table for inspection of Blood Samples from Bovine Animals." Illuminating Enginecriixg, v. 46, pp. 338-339* July 1951. 24. "Lighting for Canneries; Report of the Sub-Commitbee on Lighting." Illuminating Engineering, v. 4f, p. 4f. January 1956* 25. Linsday, E, ,\, and T. faync. "Cotton. Classing." Light. v. 21, no. 1. 1952. 26. Macadam, I). L. "Maximum Visual Efficiency of Colored Materials." J. Opt. 'a.. Am, v. 25, pp. 361 -3 6 7 . 1935* 27. MacBeth, N. and D. Nickerson. "Spectral Characteristics of Light Sources." Journal of the Society of Motion Picture Engineers, v. 52, pp. 157-log. February 194'9* 2o. Moon, P. The Scientific Basic of Illumination Engineering. McGrawHill Book Co. Hew York. 1937. "Surface Color." ASTM Bulletin J. Opt. See. A m . v. 2 3 , p. 44, 1935* The Magazine of ■ i t ■ > d— • r a-choU soij, :.j. o I*# '_v-_,r cur iuitocm^ 1 lo so.Lor„niO Lexiox X'OLt.u* i* t'» ij0r-» v# 40, no. 7, pp. 446-4V . July lyfC . 3*-’• Nickerson, f. 'Artificial Daylightinj for Color Grading of Agricultural rrelucts.” 7 . Opt. foe . .0,1. v , 29, .v . i, Pr* 1-9. 1932. ~~ 33. Nickerson, 1. "Cotton Classing by .xtificiai LiglL." Engineering. v. 4-7, no. ; , 1larch 1952. IUnulir. 34. Nickerson, 1. "The Illuininant in Textile Color latching." EngInccring. v. 43, no. 4, pp. 416-467. April 1942, 35 * Nickerson, "The Illuminant in Textile Color 1 a telling. " Soc. .v *. v. jo, no • lj jjp* 45o -4GO. May 194 o. 1.M e_. 36. Osbom, -1. h. and If. C . IL.nyon. "A General Method of Color Ore Iill. w Eng. Chen, i'-iul. ol. v. iC, pp. 523-30. lop tomb or 37, 'flic- xioi,loctcuiou '.j.l i.g m ts .mo x egiii-n os , i.atronal mire mi ot Le ttc r 0 .Lrculur’ -4 70 .Hay 193'^ * 31. Scofield, x # ^ , 1. Judd, and i„ , 1 . liunte. •, "A xreposed Method beslgixttug Col or. ' LSTM m ti. . .~ y If4 '.♦ 32* Cixiroi. , and C . Eroz-iA. "Effects of j !ia.i.,.;UvCxon xjUVo-1 on visual . oil 01'x.eoe art, fatigue," c_. ..p ,. ,.x, x . va j3, April "f4 5 . 40 * tiiiL oh, in o « anu 1.. .». jjiugg._x_s» January Ilf2• loma ie» clasti ..x-.oa e.s.en ► 41. Sterns, Nickerson, 1 . et af. "Discussion oosslon on SiJail ^ol Dii'fcixnceo. " . e.x i'Loan J^esbuiT Leperter. v . f j » - 944* 42. Tayloi', A. 1. and w . s. Dracojus. "ladirg of Colored Interiale Li.hit and Xutdiant nnorgy." Illiurinating Eiiginccrii' . v. 4 re. 1. March IfjC. 4f. Vogel, 11. E. "Special Inspection Lights Increase 110111.01:101)." Worxd. v. 136, p. 122. September 24, 1951, 44. Wald, C. "Spectral Sensitivity of the Human f y f v. 35, pp. 187-96. March 1945- Opt. Soc . .