Modifying CIECAM97s surround parameters for complex images in graphic arts viewing conditions

摘要

Reproducing a transparency original on a hard copy print is a cross-media reproduction task, and for the two to match when viewed simultaneously the different viewing conditions for the two media must be taken into account. When CIECAM97s is used to predict the appearance of the transparency using the 'cut-sheet' surround parameters, the impact of the viewing condition is over-predicted for this simultaneous viewing task. New values for the c and Nc surround parameters were derived for simultaneous viewing, where both print and transparency conditions are defined by ISO 3664. In a second phase, a background luminance factor Yb was calculated from the luminance of the image, border and background fields, assuming that the effect of the background decays exponentially with distance. New values for c and Nc were also calculated which assume that the transparency surround when viewed simultaneously with a print is a weighted combination of the surround conditions for the two media. When evaluated in a psychophysical experiment, reproductions made according to the optimised surround parameters found in phase 1, and the modified surround and background parameters found in phase 2, were judged to give a better match in the appearance of the two media than the CIECAM97s parameters.