Visual experiments on four displays (two LCD, one CRT and hardcopy) were conducted to determine colorimetric tolerances of images systematically altered via three different transfer curves. The curves used were: Sigmoidal compression in L*, linear reduction in C*, and additive rotations in hab. More than 30 observers judged the detectability of these alterations on three pictorial images for each display. Standard probit analysis was then used to determine the detection thresholds for the alterations. It was found that the detection thresholds on LCD\u27s were similar or lower than for the CRT\u27s in this type of experiment. Summarizing pixel-by-pixel image differences using the 90th percentile color difference in E*ab was shown to be more consistent than similar measures in E94 and a prototype E2000. It was also shown that using the 90th percentile difference was more consistent than the average pixel wise difference. Furthermore, SCIELAB pre-filtering was shown to have little to no effect on the results of this experiment since only global color-changes were applied and no spatial alterations were used
