Accuracy-Preserving Smoothing Of Color Transformation LUTs

Color transformations are frequently embodied in look-up tables (LUTs) whose content is the result of computation performed on the basis of color measurements. Noise in color measurements and device output gives LUTs that result in lack of smoothness in color transitions. Smoothing of color LUTs is therefore typically performed, often with a significant loss of accuracy. This paper proposes a method to both smooth LUTs and preserve a significantly greater degree of colorimetric accuracy than conventional methods. The key to such a result is to smooth along 1D paths where lightness change is greatest. E.g., along constant a*b* lines where CIELAB is the indexing space or along paths parallel to the line connecting the black and white points where the indexing space is device–dependent.