Color adaptation in video coding

Abstract

A video bitstream is received from an encoder, comprising encoded image portions each having a common form representing components of a channel in a color space. Each of a plurality of the encoded image portions comprises a different set of quantized values of the components, including at least a value of a first of the components being quantized from amongst a first scheme of quantized levels. Further, the received bitstream comprises a look-up table mapping the quantized levels of the first scheme to at least partially de-quantized respective levels. A de-quantizer uses the look-up table received in the bitstream to at least partially de-quantize the different quantized values of the first component in a plurality of the image portions, by converting the quantized values of the first component to at least partially de-quantized values corresponding to ones of the at least partially de-quantized levels of the first scheme.

Description

Background technique

[0001] Digital cameras tend to capture images with a high color depth much higher than typically required in practice. For example, some cameras capture samples at a depth of 10 or even 12 bits per R, G, and B channel, giving a total depth of 30 to 36 bits in RGB space.

[0002] The human eye on the other hand is generally not able to distinguish these many colors. Based on studies of human vision, it is estimated that a typical human being is able to perceive only about 2 million different colors. That corresponds to a total color depth of about 20 bits (6 to 7 bits per channel).

[0003] If the captured data is to be encoded for transmission over a network, high color depth information incurs very high bit rates and a high processing burden in encoding. Similarly, high color depths incur significant memory resources if the data is to be encoded for storage.

[0004] For this reason, raw image data captured from cameras is often quantized for the purp...

Examples

Embodiment Construction

[0029] Color depth refers to the number of bits used to represent a color. A color space refers to the channels used to represent a color (for example, consisting of a red channel (R), a green channel (G), and a blue channel (B) in an RGB color space; or a luminance channel (Y) and A system of two chroma channels (U, V)). A given color can be represented by a set of values ​​in the color space, one value for each of the channels. Each value may be, for example, a sample input from a camera, or a quantized, transformed or coded sample derived from an input from a camera.

[0030] There may also be different formats for expressing colors in a particular type of color space. For example on the YUV 4:4:4 format, for each set of four luma samples Y there is a corresponding set of four chroma samples U and another corresponding set of four chroma samples V. On the other hand in the YUV 4:2:0 format, for each group of four luma samples Y there is a corresponding group of two chrom...

Background technique

[0001] Digital cameras tend to capture images with a high color depth much higher than typically required in practice. For example, some cameras capture samples at a depth of 10 or even 12 bits per R, G, and B channel, giving a total depth of 30 to 36 bits in RGB space.

[0002] The human eye on the other hand is generally not able to distinguish these many colors. Based on studies of human vision, it is estimated that a typical human being is able to perceive only about 2 million different colors. That corresponds to a total color depth of about 20 bits (6 to 7 bits per channel).

[0003] If the captured data is to be encoded for transmission over a network, high color depth information incurs very high bit rates and a high processing burden in encoding. Similarly, high color depths incur significant memory resources if the data is to be encoded for storage.

[0004] For this reason, raw image data captured from cameras is often quantized for the purp...

Examples

Embodiment Construction

[0029] Color depth refers to the number of bits used to represent a color. A color space refers to the channels used to represent a color (for example, consisting of a red channel (R), a green channel (G), and a blue channel (B) in an RGB color space; or a luminance channel (Y) and A system of two chroma channels (U, V)). A given color can be represented by a set of values ​​in the color space, one value for each of the channels. Each value may be, for example, a sample input from a camera, or a quantized, transformed or coded sample derived from an input from a camera.

[0030] There may also be different formats for expressing colors in a particular type of color space. For example on the YUV 4:4:4 format, for each set of four luma samples Y there is a corresponding set of four chroma samples U and another corresponding set of four chroma samples V. On the other hand in the YUV 4:2:0 format, for each group of four luma samples Y there is a corresponding group of two chrom...

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