Method and apparatus for dynamic contrast improvement in video pictures
AssigneeDeutsche Thomson-Brandt GmbH
InventorSahmusa Akbayir
Life of this patent
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Abstract
A method and apparatus for dynamic contrast improvement in video pictures. There is a strong demand for picture contrast but each video display has a limited dynamic range. The picture contrast can't be increased by simply increasing the video signal amplitude because exceeding the display dynamic range in some video scenes causes unwanted disturbing effects. According to the present invention the video pictures are analysed framewise in real time and the parameters of a transfer function for contrast improvement are adjusted depending on the analysis results for the best subjective picture quality.
Claims15
Method for dynamic contrast improvement of video pictures comprising the steps of analysing the video pictures framewise or field wise in real time regarding their picture content and adjusting the parameters of a transfer function which determines the amount of alteration of the luminance and/or chrominance signal of the video picture for contrast improvement, wherein the transfer function is a dual segment transfer function with an adaptive pivot point which separates the two segments, the picture frames or fields are analysed for the following characteristics:
- image average brightness;
- and
- dark sample distribution, and the adaptive pivot point is adapted in dependence on the image average brightness value, and the dark sample distribution value is used to determine the segment gain of the lower segment of the dual segment transfer function.
Apparatus for dynamic contrast improvement of video pictures comprising:
- an image analysis unit wherein the video pictures are analysed frame wise or field wise regarding to their picture content;
- a transfer function adaptation unit wherein the transfer function for the luminance and/or chrominance signal of the video pictures is adapted dependent on the results of the image analysis unit;
- and
- an adaptive signal splitter in which a noise reduced luminance signal is generated which is processed in the transfer function adaptation unit.
Apparatus for dynamic contrast improvement of video pictures comprising:
- an image analysis unit wherein the video pictures are analysed frame wise or field wise regarding to their picture content;
- a transfer function adaptation unit wherein the transfer function for the luminance and/or chrominance signal of the video pictures is adapted dependent on the results of the image analysis unit;
- and
- a color saturation compensation unit which compensates for the color saturation effect due to the none-linear processing of the luminance component in the transfer function adaptation unit.
Dependencies are inferred from the claim text.