Digitalization of visual discrimination threshold and acceptable tolerance of color depth by psychophysical experiments

Abstract

Color depth is of great importance to both dyes and dyeing. The assessments of properties such as color fastness, relative dye strengths require dyed fabric to be adjusted to a specific depth level. However, the study of discrimination threshold and acceptable tolerance of color depth is limited. In this study, we attempted to investigate them. Acceptability (Pass/Fail) psychophysical visual experiments were performed twice by 16 normal color version observers on approximately 1206 samples for 6 standard depths in 3 hues, yielding approximately 40,000 visual assessment data points. The color depth formula, Yang3, which performed best in linearity to color depth in a previous study, was selected to calculate the color depth values YCD3 of the samples. The calculated and the visual data were bridged statistically. Experimental results show that the average discrimination threshold and acceptable tolerance of color depth are approximately 0.45 and 2.15 in YCD3, respectively. Furthermore, the details of different hues, lighter and deeper, male and female perspectives were analyzed and discussed. The Yang3 formula exhibited uniformity at different standard depths, as expected.

Investigation on the equi‐depth of color depth formulas based on color discrimination threshold and acceptable tolerance

“…The discrimination thresholds were automatically calculated by self‐programmed software. The calculation method was performed according to a prior study 25 . In the discrimination threshold, all of the samples were divided into “pass” and “fail” groups.…”

“…Both Yang2 and Yang3 formulas were proposed using square roots and cube roots of X, Y, and Z. 17 The Yangn formula contains Yang1, Yang2, Yang3, as shown in Equation ( 11) below. Yang1 exhibits the optimum discriminative degree, while Yang2 exhibits the second-best discriminative degree.…”

“…The calculation method was performed according to a prior study. 25 In the discrimination threshold, all of the samples were divided into "pass" and "fail" groups. And then two groups' cumulative percentage were calculated to plot against the color depth difference.…”

“…Yang3 exhibits the best linearity, which is followed by Yang2 18 . Different formulas can be selected according to the application for which they are required. where YCD n represents color depth; X w , Y w , and Z w are the tristimulus values of ideal white; X sp , Y sp , and Z sp are the tristimulus values of samples 16,17 . The calculation of the tristimulus values for each sample were obtained using an X‐Rite Color i7 Spectrophotometer (conformed with ASTM E08‐15).…”

“…where YCDn represents color depth; X w , Y w , and Z w are the tristimulus values of ideal white; X sp , Y sp , and Z sp are the tristimulus values of samples. 16,17 The calculation of the tristimulus values for each sample were obtained using an X-Rite Color i7 Spectrophotometer (conformed with ASTM E08-15). n = 1, 2, or 3, means Yang1 formula, Yang2 formula, and Yang3 formula, respectively.…”