METHOD AND DEVICE FOR DECOSING A COLOR PICTURE
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Abstract
The present disclosure generally relates to a device and a method of decoding a color picture from a bitstream. It comprises: —obtaining an expanded range luminance as a first component by applying a nonlinear dynamic expansion function to a luminance component obtained from the bitstream, wherein said nonlinear dynamic expansion function is determined depending on an inverse of a dynamic reduction function that has been applied to an original luminance component obtained when encoding the color picture; —obtaining a second component by calculating a square root of a difference between a value determined by the first component and another value computed as a linear combination of a multiplication product of two chrominance components and square values of the two chrominance components obtained from the bitstream; and —obtaining at least one color component of the color picture to be decoded at least from said second component and said two chrominance components by determining said at least one color component as a linear combination of the second component and the two chrominance components.
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Citations
29 Claims
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1-14. -14. (canceled)
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15. A method of decoding a color picture from a bitstream, comprising:
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obtaining a final luminance component (L) by linear combining a luminance (L′
) and chrominance (U′
, V′
) components obtained from a bitstream;obtaining a first component (Y) by applying a non-linear dynamic expansion function on said final luminance component (L) in order that the dynamic of the first component (Y) is increased compared to the dynamic of the final luminance component (L); obtaining a normalized multiplicative factor (β
γ
′
) by dividing a multiplicative factor (β
′
) obtained from the bitstream by the square root of the first component;recovering at least one color component (RGBHDR) of the color picture to be decoded from said chrominance components (U′
, V′
) and said first component (Y) by;obtaining intermediate chrominance components (, {circumflex over (V)}r) by multiplying the chrominance components (U′
, V′
) by said normalized multiplicative factor (β
γ
′
);obtaining at least one intermediate color component (, , ) from the squares of said two intermediate chrominance components (, {circumflex over (V)}r), the product of said two intermediate chrominance components (, {circumflex over (V)}r) and a color transform matrix (C); and calculating at least one color component (RGBHDR) of the decoded color picture by squaring the product of the square root of the first component (Y) by one of said at least one intermediate color component (, , ). - View Dependent Claims (16, 17, 18, 19, 20, 27, 28, 29)
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21. A device of decoding a color picture from a bitstream, comprising a processor configured to:
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obtain a final luminance component by linear combining a luminance and chrominance components obtained from a bitstream; obtain a first component by applying a non-linear dynamic expansion function on said final luminance component in order that the dynamic of the first component is increased compared to the dynamic of the final luminance component; obtain a normalized multiplicative factor by dividing a multiplicative factor (B′
) obtained from the bitstream by the square root of the first component;recover at least one color component of the color picture to be decoded from said chrominance components and said first component by; obtaining intermediate chrominance components (, {circumflex over (V)}r) by multiplying the chrominance components (U′
, V′
) by said normalized multiplicative factor (β
γ
′
);obtaining at least one intermediate color component (, , ) from the squares of said two intermediate chrominance components (, {circumflex over (V)}r), the product of said two intermediate chrominance components (, {circumflex over (V)}r) and a color transform matrix (C); and calculating at least one color component (RGBHDR) of the decoded color picture by squaring the product of the square root of the first component (Y) by one of said at least one intermediate color component (, , ). - View Dependent Claims (22, 23, 24, 25, 26)
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Specification