Abstract: An environment was established to perform device-independent color reproduction of full-color pictorial images. In order to determine the required precision for this environment, an experiment was performed to psychophysically measure colorimetric tolerances for six images using paired comparison techniques. These images were manipulated using 10 linear and nonlinear functions in the CIELAB dimensions of lightness, chroma, and hue angle. Perceptibility tolerances were determined using probit analysis. From these results, the necessary precision in number of bits per color channel was determined for both the CIELAB and the CRT rgb device color spaces. For both the CIELAB color space and the CRT rgb device space, approximately eight color bits per channel were required for imperceptible color differences for pictorial images, and 10 bits per channel were required for computational precision.