Method and device for decoding a color picture

A method comprising:

• receiving a luminance and chrominance components from a bitstream;
• obtaining a further luminance component by linear combining said luminance and chrominance components;
• obtaining a first component by applying a non-linear dynamic expansion function on said further luminance component in order that the dynamic of the first component is increased compared to the dynamic of the further luminance component;
• receiving a multiplicative factor from the bitstream;
• obtaining a normalized multiplicative factor from said multiplicative factor and the first component;
• recovering at least one color component of a color picture from said chrominance components and said first component by:
• obtaining intermediate chrominance components from the chrominance components and said normalized multiplicative factor;
• obtaining at least one intermediate color component from said two intermediate chrominance components, the product of said two intermediate chrominance components and a color transform matrix;
• and
• displaying at least one color component of the decoded color picture obtained from the first component and one of said at least one intermediate color component.

An apparatus, comprising:

• a receiver for receiving a luminance, a chrominance components and a multiplicative factor from a bitstream;
• a processor configured to:
• obtaining a further luminance component by linear combining said luminance and chrominance components;
• obtaining a first component by applying a non-linear dynamic expansion function on said further luminance component in order that the dynamic of the first component is increased compared to the dynamic of the further luminance component;
• obtaining a normalized multiplicative factor from said multiplicative factor and the first component;
• recovering at least one color component of a color picture from said chrominance components and said first component by:
• obtaining intermediate chrominance components from the chrominance components and said normalized multiplicative factor;
• obtaining at least one intermediate color component from said two intermediate chrominance components, the product of said two intermediate chrominance components and a color transform matrix;
• and
• a display for displaying at least one color component of the decoded color picture obtained from the first component and one of said at least one intermediate color component.

A method comprising:

• obtaining a first component by applying a non-linear dynamic reduction function on a luminance component of a color picture in order that the dynamic of the first component is decreased compared to the dynamic of the luminance component;
• obtaining two chrominance components from color components of the color picture;
• obtaining a further luminance component by linearly combining the first component and the two chrominance components;
• and
• encoding the further luminance component and the two chrominance components.

An apparatus comprising a processor configured to:

• obtaining a first component by applying a non-linear dynamic reduction function on a luminance component of a color picture in order that the dynamic of the first component is decreased compared to the dynamic of the luminance component;
• obtaining two chrominance components from color components of the color picture;
• obtaining a further luminance component by linearly combining the first component and the two chrominance components;
• and
• encoding the further luminance component and the two chrominance components.