Research on large color difference evaluation using printed samples
A grey-scale psychophysical experiment was carried out for evaluating color differences using printed color patches. In total, 100 pairs of printed samples were prepared with an average ΔE*ab of 13.8 units. Each pair was assessed 60 times by a panel of 20 normal color vision observers. The visual results were used to test the existing color-difference formulae. The results showed that all formulae gave quite satisfactory performance except OSA-Ep-Gu, which is the formula for calculating the magnitude of small-medium color difference. The optimized kL values were used to compare with the medium color difference (MCD) of the earlier studies. The results showed that they agreed well with each other.
Colour-Difference Evaluation Using CRT Colours. Part II: Parametric Effects
A large set of colour discrimination data based upon cathode ray tube (CRT) colours was accumulated and described in Part I of this article. The experiment was divided into 16 different phases according to different viewing parameters studied: sample size (large and small), background (mid-gray, white, black, gray, red, yellow, green, and blue), frame (black and no frame), and width (no gap, 1-pixel, 2-pixel, and large gap) and colour (mid-gray and black) of separations between pairs of samples. This part of the article investigates the changes of perceived colour differences caused by these variables. In addition, investigations were made to find the results from which phase agree best with results for surface colours. © 2001 John Wiley & Sons, Inc. Col Res Appl, 26, 403–412, 2001
Colorimetric data for samples of OSA uniform color scales
Colorimetric specifications and measured values of one of the sets of cards issued by the Optical Society of America for its Committee on Uniform Color Scales are reported. In addition to the CIE values for illuminant D65 and color-mixture data for 10° observing fields, the corresponding L,j,g notations of the committee are also given. The average discrepancy between the actual colors and their specifications is 14% of the intended difference between pairs of nearest neighbors of the full-step set of colors. The full-step set of 424 colors exhibits 2058 pairs of nearest neighbors. The root-mean-square deviation from the average difference, evaluated by use of the committee’s formula for color difference, is 12%. To bisect the color differences in the frequently used medium-lightness range of low-saturation colors, 134 additional colors are included in the set. Together with 13 embedded and 38 immediately adjacent colors of the full-step set, they provide 740 half-step pairs of colors. The rms deviation is 17% of their average.