Colorimetric tolerances of various digital image displays

Abstract

While color difference formulas such as CIE94 work reasonably well for simple uniform color patches in direct edge contact, their application to pictorial images has only recently been investigated. In this study, perceptible color difference tolerances were developed for pictorial images displayed on a CRT display, two LCD displays, and on continuous tone hardcopy output. Three transforms were used to represent common global image processing steps. Reductions in contrast were simulated using a sigmoidal compression in L*. Reductions in system gain were modeled using a multiplicative reduction in C*ab. Overall color casts were modeled using an additive offset in hab. For sigmoidal L* compression, the prints had lower sensitivity than the other three displays. For multiplicative reduction in C*ab, the prints had higher sensitivity than the others. For rotations in hab, the prints had the highest sensitivity, followed by one of the LCDs, then the remaining displays, which had similar performance to each other. Thresholds are also expressed colorimetricly using pixel by pixel comparisons with and without S-CIELAB pre-filtering using three color difference formulas. In general, the overall thresholds ranged from 1 to 3 ΔE for each of the three perceptual attributes. In this experiment, S-CIELAB pre-filtering did not have a significant effect.