| 摘要 |
In present television sets, user color saturated control is executed in a non-linear signal domain due to the gamma conversion inherent of the camera. This results in the display of exaggerated colors when the saturated control is increased. The present invention provides a A luminance control method comprising the steps of providing an original image signal ((Y', R'-Y', B'- Y')) having a luminance component (Y') and a color component (R'-Y', B'-Y') to a first processing stream and a second processing stream, wherein the first processing stream comprises the steps of: applying a saturation control to the original image signal ((Y', R'-Y', B'-Y')) resulting in a saturation controlled image signal ((Y', sat*(R'-Y'), sat*(B'- Y'))), and predicting a first predicted image signal ((Ys", Rs"-Ys", Bs"-Ys")) by further processing thereof; the second processing stream comprises the steps of: predicting a second predicted image signal ((Y I ", R1 "-Y 1 ", BI"-Y1 ")) by processing of the original image signal ((Y', R'- Y', B'-Y')); providing a correction factor (Y1 " /Ys") by comparing the luminance (Ys") of the first predicted image signal ((Ys", Rs"-Ys", Bs"-Ys")) to the luminance (Y1 ") of the second predicted image signal ((Y1 ", R1 "-Y 1 ", B 1 "-Y1 ")); applying the correction factor (Y1 "/Ys") to correct one of the image signals of the first processing stream to give a display signal ((Ro', Go', Bo')). Thereby the current invention maintains the luminance output as a function of the saturation control. Le. the luminance of the display is predicted for the case where the saturation is amended. This predicted luminance is higher or lower due to the increased or decreased saturation and compared with the predicted luminance with unamended saturation. This comparison provides a correction factor that is applied to an image signal with amended saturation before the image signal is applied to the display. The result is that at an increasing saturation control a very natural change of the colors occurs where the conventional method of saturation control will cause an exaggerated and unnatural color reproduction.
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