Martin scale Martin scale The Martin scale is an older version of color scale commonly used in physical anthropology to establish more or less precisely the eye color of an individual; it was created by the anthropologist Martin in the first half of the 20th century. Later he improved this scale with cooperation of Dr. Schulz – the Martin-Schultz scale. The original Martin scale, summarized below, consists of 16 colors (from light blue to dark brown-black) that correspond to the different eye colors observed in nature due to the amount of melanin in the iris. The numbering is reversed in order to
Color difference Commonly used values are 2:1 for acceptability and 1:1 for the threshold of imperceptibility. The distance of a color formula_27 to a reference formula_28 is: CMC l:c is designed to be used with D65 and the CIE Supplementary Observer. The formula is not a metric but rather a quasimetric because it violates symmetry, parameter T is based on the hue of the formula_32 alone. This reference color means that the color difference from the first color to the second color is different than the color distance from the second color is to the first. Tolerancing concerns the question "What is