| 摘要 |
Conventional color saturation control CSC in a non-linear signal domain may result in exaggerated and unnatural looking colors. The invention proposes an image signal processing method ( 30 A, 30 B) of a color saturation control ( 17 ) which applies a gain value ( 27 ) to the saturation controlled image signal (Y', satx(R'-Y'), satx(B'-Y')) in a color restoration ( 10 ) which results in an output signal (Yo', (R'-Y')o, (B'-Y')o). The gain value ( 27 ) is determined such that a maximum value of a color in the input signal is maintained in the output signal (Yo', (R'-Y')o, (B'-Y')o). Thereby in particular the symmetry of the 3 Dcolor space is maintained, preferably by controlling at least the maximum values of three primary colors (R, G, B) when increasing the saturation. In a preferred configuration the saturation controlled color difference image signals (satx(R'-Y'), satx(B'-Y')) are transformed to the RGB-domain to obtain an RGB-measure of the increased saturation. Also the color difference input image signals (R'-Y', B'-Y') are transformed to analyze the original level of saturation. On this basis a first (RGBmaxsat') and a second (RGBmax') color maximum value are determined and used to determine the gain value ( 27 ).
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