DYNAMIC SOFTCLIPPING OF VIDEO LEVELS

摘要

A method for improvement of contrast in an image shown on a display having a range of displayable video levels. The method comprises providing input video levels representing the image, said levels being within said displayable range; providing a transfer function (120, 121) having a slope greater than one everywhere in a gain region (130) of said displayable range, and a slope greater than zero and less than one everywhere in a softclip region (131) of said displayable range, said regions (130, 131) meeting at a threshold level (125), the transfer function (120, 121) being adapted to transfer any input video level within said displayable range to an output level within displayable said range; and transforming said input levels into output levels within said range, using the transfer function (120, 121). According to the invention, instead of "hardclipping" there is a "softclipping" of levels. Hence, compared to conventional methods, a higher gain may be used. In practical situations, the gain applied in the gain region typically may be up to 4.