Hunter color 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. 

In the work with cottonseed flours, we used the Hunterlab color meter D25D2A and expressed these measurements as Hunter L, a, b color values. These are coordinates of the three-dimensional opponent-color space shown in Figure 2. The L value measures lightness, or the amount of light reflected or transmitted by the object. The a and b values are the chromaticity coordinates from which information about hue and saturation can be obtained. The a value measures redness when plus and greenness when minus. The b value measures yellowness when plus and blueness when minus. 

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. 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 ...

E Difference Meter (Neotec) Hunter Color and Tristimulus reflectance NM... 

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. 

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

AE color change of 1.06 (Hunter D-25 D2-P color meter) Geloy 1220 GE Plastics Specimen 1 mm (0.040 in) thick dark brown extruded profile... 

Color meters (Hunter Lab, Agtron [AACC Method 14-30] and others)... 

For most other purposes, both before and after processing, color is measured using a colorimeter such as a Minolta Chroma Meter (Minolta Corp., Ramsey, NJ). The instrument is calibrated against a standard-white (Minolta) reference plate. Hunter L (whiteness), a (greenness) and b (yellowness) values were determined for each sample and made directly from the potato surface (Nourian et al., 2003). 

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. 

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. 

The most known among WPC researchers and engineers is the Hunter Lab color scale and a Hunter Lab Color scale meter. They were basically developed in the 1950s and 1960s, and the current formulas were finalized in the mid of 1960s. The most challenging question in that time and earlier was how to represent colors based solely on the numbers ... 

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