Display management for high dynamic range video
AssigneeDolby Laboratories Licensing Corporation
InventorRobin Atkins
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Abstract
A display management processor receives an input image with enhanced dynamic range to be displayed on a target display which has a different dynamic range than a reference display. The input image is first transformed into a perceptually-quantized (PQ) color space, preferably the IPT-PQ color space. A color volume mapping function, which includes an adaptive tone-mapping function and an adaptive gamut mapping function, generates a mapped image. A detail-preservation step is applied to the intensity component of the mapped image to generate a final mapped image with a filtered tone-mapped intensity image. The final mapped image is then translated back to the display's preferred color space. Examples of the adaptive tone mapping and gamut mapping functions are provided.
Claims17
A method comprising:
- accessing an input image in a first color space with a first dynamic range;
- applying a color transformation step to the input image to determine a first output image in a perceptually-quantized IPT (IPT-PQ) color space, the first output image comprising intensity pixel values and chroma components pixel values, wherein the color transformation step comprises applying a non-linear perceptual quantizer function to a function of the input image;
- applying a color-volume mapping function to the first output image to generate a tone-mapped output image, the tone-mapped output image comprising intensity pixel values and chroma components pixel values,
- wherein the color-volume mapping function comprises a tone mapping function, a saturation mapping function, and a pixel saturation estimate function,
- wherein the tone mapping function generates the intensity pixel values of the tone-mapped output image by applying a non-linear mapping to the intensity pixel values of the first output image,
- wherein the saturation mapping function generates the chroma components pixel values of the tone-mapped output image by adjusting the chroma components pixel values of the first output image based on changes in intensity,
- wherein the pixel saturation estimate function computes a saturation metric (S) as the sum of squares of the chroma components pixel values of the first output image, wherein the saturation metric is applied to the tone-mapped output image to darken bright saturated colors and to desaturate highly saturated colors, thereby modifying the intensity pixel values and the chroma components pixel values;
- and
- applying a detail preservation function to the modified intensity pixel values of the tone-mapped output image to generate intensity pixel values of a filtered tone-mapped output image, the filtered tone-mapped output image comprising the modified chroma components pixel values of the tone-mapped output image.
Dependencies are inferred from the claim text.