Abstract: The color signals to be printed by a thermal color transfer printer are processed in order to provide gamma and temperature compensation for nonlinearities in the responses of the colored dyes used in the thermal printing ribbon and also to provide color compensation to correct for any overlap in the spectral response of these colored dyes. Color data signals are sampled and multiplexed to place the main or print color signal, which is determined by the color of the dye in position in front of the thermal head at that instant, in the center of a multiplexed, time-sharing arrangement with the non-print color signals arranged on either side. The multiplexed signal is digitized and used to address a read only memory containing compensation curves to provide both gamma compensation and color compensation, and the compensated signals are adjusted in gray scale magnitude before being pulse width modulated for driving the thermal head to produce the desired color, hard-copy print.