Extending image dynamic range
First Claim
Patent Images
1. A method to encode a video signal, the method comprising:
- receiving an input video signal in a first content version in a first dynamic range and a second content version in a second dynamic range, wherein the first dynamic range is higher than the second dynamic range;
applying a normalization process to the first content version and the second content version to generate a third content version, a fourth content version, and an invertible mapping function between the third and the fourth content versions, wherein the third content version represents a modified version of the first content version and the fourth content version represents a modified content version of the second content version, wherein applying the normalization process comprises;
accessing a first image and a second image, wherein for a scene in the input video signal, the first image and the second image are corresponding representations of the scene in the first content version and the second content version;
initializing a third image in the third content version using the first image;
initializing a fourth image in the fourth content version using the second image;
generating an estimated invertible mapping function between the third image and the fourth image;
evaluating the accuracy of the invertible mapping function; and
if the evaluation step does not meet a certain criterion, modifying the mapping function and at least one of the third image and the fourth image; and
generating an output coded bit stream based on a coded representation of the fourth content version and the invertible mapping function.
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Abstract
Enhancing image dynamic range is described. An input video signal that is represented in a first color space with a first color gamut, which is related to a first dynamic range, is converted to a video signal that is represented in a second color space with a second color gamut. The second color space is associated with a second dynamic range. At least two (e.g., three) color-related components of the converted video signal are mapped over the second dynamic range.
45 Citations
12 Claims
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1. A method to encode a video signal, the method comprising:
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receiving an input video signal in a first content version in a first dynamic range and a second content version in a second dynamic range, wherein the first dynamic range is higher than the second dynamic range; applying a normalization process to the first content version and the second content version to generate a third content version, a fourth content version, and an invertible mapping function between the third and the fourth content versions, wherein the third content version represents a modified version of the first content version and the fourth content version represents a modified content version of the second content version, wherein applying the normalization process comprises; accessing a first image and a second image, wherein for a scene in the input video signal, the first image and the second image are corresponding representations of the scene in the first content version and the second content version; initializing a third image in the third content version using the first image; initializing a fourth image in the fourth content version using the second image; generating an estimated invertible mapping function between the third image and the fourth image; evaluating the accuracy of the invertible mapping function; and if the evaluation step does not meet a certain criterion, modifying the mapping function and at least one of the third image and the fourth image; and generating an output coded bit stream based on a coded representation of the fourth content version and the invertible mapping function. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10, 11, 12)
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6. The method of claim one, wherein given a mapping function M[ ] and its inverse M−
- 1[ ];
VDR′
=M−
1[SDR′
] and SDR′
=M[VDR′
],wherein VDR′
denotes the third coded version of the input video signal and SDR′
denotes the fourth coded version of the input video signal.
- 1[ ];
Specification