New diagnostic pseudoisochromatic plates for dichromats based on subtractive color matches

Further subtractive color matches obtained with the Lovibond Tintometer have confirmed the convergence data for dichromats obtained in a previous study. The characteristic color confusions obtained for 15 protanopes and 15 deuteranopes have been used in the selection of pairs of inks for use in the production of new screen-printed pseudoisochromatic plates incorporating geometric symbols and minimum form parameters. The success of these diagnostic plates is found to depend both on the careful selection of the inks to lie upon appropriate pseudoisochromatic lines but also on the reflected luminance contrast between the symbol and the background matrix of dots.