MAINTENANCE OF HUE IN A SATURATION-CONTROLLED COLOR IMAGE

摘要

A hue error may occur upon a saturation control CSC if for a given pixel not only the color becomes more saturated but also the color of pixel changes. In a first variant the invention proposes to predict the saturated color after a saturation increase by applying in a first processing stream (23) an estimated gamma-function of a display device (11) to the saturated signal (Y', satx(R'-Y'), satx(B'-Y)) thus obtaining a saturated color and in a second processing stream (25) to the original signal (Y', (R'-Y'), (B'-Y)) thus obtaining the original color. The saturated color is corrected to the original color, while maintaining its increased saturation. In a second variant predicting the hue of the output of the display becomes unnecessary by offering a hue correction (35) after the color saturation control (17) when negative color contributions happen. In a third variant it is possible to apply a color difference signal after the color saturation control (17) to empirically approximate the hue correction.