We propose an algorithm that transforms a digitized color image so as tosimulate for normal observers the appearance of the image for people who havedichromatic forms of color blindness. The dichromat's color confusions arededuced from colorimetry, and the residual hues in the transformed image arederived from the reports of unilateral dichromats described in the literature.We represent color stimuli as vectors in a three-dimensional LMS space, andthe simulation algorithm is expressed in terms of transformations of thisspace. The algorithm replaces each stimulus by its projection onto a reducedstimulus surface. This surface is defined by a neutral axis and by the LMSlocations of those monochromatic stimuli that are perceived as the same hueby normal trichromats and a given type of dichromat. These monochromatic stimuliwere a yellow of 575 nm and a blue of 475 nm for the protan and deutan simulations, and a red of 660 nm and a blue–green of 485 nm for the tritan simulation.The operation of the algorithm is demonstrated with a mosaic of square colorpatches. A protanope and a deuteranope accepted the match between the originaland the appropriate image, confirming that the reduction is colorimetricallyaccurate. Although we can never be certain of another's sensations, the simulationprovides a means of quantifying and illustrating the residual color informationavailable to dichromats in any digitized image.
© 1997 Optical Society of America
[Optical Society of America ]
Hans Brettel, Françoise Viénot, and John D. Mollon, "Computerized simulation of color appearance for dichromats," J. Opt. Soc. Am. A 14, 2647-2655 (1997)