Range Definition of Acceptable Differences of Chromatic Value by Color Measurement and Visual Estimation

Under the defined conditions, 24 samples, considered to be similar to the chosen standards in their chromatic characteristics, were chosen by the visual method among 126 similar samples. The standard and all the tested (investigated) samples were measured on the spectral photometer. The measured reflenctandes were recalculated into numerical values of CIELAB. Based on the data obtained by the instrumental method, the developed differences of 24 visually similar samples were calculated and analyzed. The limits of the visual judgment expressed as AL*, AH*a^, AC*aj, were numerically defined. The developed color differences are usually defined by one numerical data, i.e., ABased on the analysis of the calculated chromatic values of CIELAB and their chromatic influence in the visual estimation of the change of the expression of AE*ab, it is suggested to use three numerical values, AL*, &H*ab, AC*ab, to define color differences. In this way, the values that caused the developed differences can be defined