Color-difference meter

Photoelectric-Colorimetric Method. Although the recording spectrophotometer is, for food work at least, a research tool, another instrument, the Hunter multipurpose reflectometer (4), is available and may prove to be applicable to industrial quality control. (The newer Hunter color and color difference meter which eliminates considerable calculation will probably be even more directly applicable. Another make of reflection meter has recently been made available commercially that uses filters similar to those developed by Hunter and can be used to obtain a similar type of data.) This instrument is not a spectrophotometer, for it does not primarily measure the variation of any property of samples with respect to wave length, but certain colorimetric indexes are calculated from separate readings with amber, blue, and green filters, designated A, B, and G, respectively. The most useful indexes in food color work obtainable with this type of instrument have been G, which gives a... 

Obtained with a Hunter Color and Color difference Meter, Model D25... 

Analytical Methods. The samples were analyzed by standard AACC (21) procedures for moisture (air-oven method), protein (Method 46-13), crude fat (Method 30-25), crude fiber (Method 32-10), insoluble dietary fiber (Method 32-20) and ash (600°C, 3 hr). Starch content was determined by the polarimeter method (Method 76-20) and total sugars by Method 80-60. Color characteristics of the dried products were evaluated with the Hunter Color Difference Meter. 

Product Colours. Both legume flours showed creamy-yellow colours under the Hunter Color Difference Meter but fababean flour was also slightly greenish (Table V). Pin milling improved the lightness of the flour and this colour was retained by the protein and starch fractions at the expense of the yellow values. The proteinates were light brown in appearance whereas the refined starches were essentially white. The refined fiber retained only a light shade of yellow as compared to the other products. 

A Hunter Color and Color Difference Meter was used to evaluate flour color. The effect of roasting condition on Hunter L values of flours indicated that lightness values (L) decreased with increased roasting temperature and time with all navy bean cotyledonary fractions possessing a clear light appearance. 

Color-Difference Meter. A specially designed reflection meter for assessing small color variations. 

Transmission and Haze Measurements. Light transmission measurements were made with a Gardner color difference meter and the haze measurements, using a Hazemeter attachment on the Gardner colorimeter. Test pieces were 3 X 3 X % inch sheets having glossy surfaces obtained by molding on chrome plates. All measurements were made at 23°C. 

Yellowness Index. The yellowness of the 50-mil plaques used for stabilization studies was measured directly from a Hunter D-25 color difference meter equipped with a 90° sphere attachment. The samples were placed in the reflectance port of the sphere using a standard white ceramic as backing. The instrument is designed to give direct yellowness index values as described in ASTM D-1925. 

Further studies into the possible effects historic cleaning methods had on garments could be valuable in explaining some fabric colorant behaviors presently exhibited by collected textile items of historical significance. It is recommended that the usefulness of x-ray analysis techniques to determine colorant type or residual effects of treatment be studied further. Tests similar to those conducted in this study could be done to test colorant responses to situations using a more refined color comparison method, such as the Hunter Color Difference Meter. 

Calculated from L,a,b values on a Hunter color difference meter (average of six readings on each sample) exposure in Weatherometer is listed in kilojoules per square meter (ambient dry bulb temperature, 85°F 3° wet bulb temperature, 70°F 4°, black panel temperature 100°F % relative humidity, 50 8%). Each 110 kJ/m2 corresponds to about 20 h exposure to noon sunlight conditions. 

Color Measurements. Color measurements were made on the samples with a Hunterlab model D25D2 color difference meter after conditioning. A white standard plate was used as a backing. Both fronts and backs of the cloths were measured three times, and the results were averaged. Color differences are reported in the LAB system. 

Color. A Hunter color difference meter, Model D25D2 was used to evaluate the color of the canned products. A yellowish green... 

Table VIII. Hunter Color Difference Meter Readings of Canned Kiwifruit Nectars ...

To determine the effect of antioxidant and antimicrobial agents on juice stability, pH (Orion Research Co. Analog pH Meter, Model 301). juice color (Hunter D25 Color Difference Meter) and microbial total counts were monitored as indicators of juice quality. 

HUNTER, R. s. (1958) Photoelectric color difference meter. Journal of the Optical Society of America, 48, 985-995. 

F (1) Color Difference Meter Macbeth Spectrophotometer MS-2000 Integrating sphere 0°/d C... 

Color and Color Difference Meter XL-23 Tristimulus colorimeter C... 

A uniform color scale devised by Hnnter in 1958 for nse on a color difference meter, based on the opponent color theory of vision. 

Hunter color difference equation n. Generally refers to the color difference equation used for calculating color differences on certain color difference meters (especially those made by Hunter Labs and Gardner Instruments, VA, USA). It is a simplified equation to approximate the NBS equation ... 

Gardner Laboratory, Inc. 1950. Description and instructions for Hunter color and color-difference meter (Brochure). Henry A. Gardner Lab., Inc., Bethcsda, Maryland. 

Hunter, R. S. 1948a. Photoelectric Color-Difference Meter. J. Opt. Soc. Amer. 38, 661. Hunter, R. S. 1948b. Accuracy precision and stability of a new photoelectric Color-Difference Meter. J. Opt. Soc. Amer. 38, 1094. 

Younkin, S. G. 1950a. Application of Hunter Color-Difference Meter to a tomato color... 

The instrumental measurement of specimens can be done resulting in color coordinates and color-difference values by using a tristimulus colorimeter. This instrument is also known as a tristimulus filter colorimeter or a color-difference meter. The test method covers both reflected and transmitted light. The method is generally suitable for any non-fluorescent, planar, object-color specimens of all gloss levels (14). 

E 450 Method for Measurement of Color of Low-Colored Clear Liquids Using the Hunterlab Color Difference Meter ... 

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