Method and device for predictive picture encoding and decoding

A method for decoding, comprising:

• obtaining a prediction value of a current color component of a sample of a block of a picture;
• decoding a residual value for the sample;
• determining a reconstructed value for the sample from the decoded residual value and from the prediction value to using both a mapping function and an inverse mapping function that is the inverse of the mapping function;
• wherein determining the reconstructed value comprises:
• mapping the prediction value with an the mapping function to obtain a mapped prediction value;
• and
• obtaining an intermediate value representative of a sum of the mapped prediction value and the residual value;
• the reconstructed value being obtained by mapping the intermediate value with the inverse mapping function.

A device for encoding, comprising electronic circuitry adapted for:

• obtaining a prediction value of a current color component of at least a sample of a block of a picture;
• determining a mapped residual value from a source value of said current color component and from the prediction value using a mapping function;
• and
• encoding the mapped residual value into a bitstream;
• wherein the determining of the mapped residual value comprises:
• mapping the prediction value with the mapping function to obtain a mapped prediction value;
• determining an intermediate residual value representative of a difference between the mapped prediction value and the source value;
• and
• mapping the intermediate residual value using the mapping function.

A device for decoding, comprising electronic circuitry adapted for:

• obtaining a prediction value of a current color component of a sample of the a block of a picture;
• decoding a residual value for the sample;
• determining a reconstructed value for the sample from the decoded residual value and from the prediction value using both a mapping function and an inverse mapping function that is the inverse of the mapping function;
• wherein the determining of the reconstructed value comprises:
• mapping the prediction value with the mapping function to obtain a mapped prediction value;
• and,
• obtaining an intermediate value representative of a sum of mapped prediction value and the residual value;
• the reconstructed value being obtained by mapping the intermediate value with the inverse mapping function.

A signal comprising data generated by a method for encoding comprising:

• obtaining a prediction value of a current color component of a sample of a block of a picture;
• determining a mapped residual value from a source value of said current color component and from the prediction value using a mapping function;
• and
• encoding the mapped residual value into a bitstream;
• wherein determining the mapped residual value comprises:
• mapping the prediction value with the mapping function to obtain a mapped prediction value;
• determining an intermediate residual value representative of a difference between the mapped prediction value and the source value;
• and
• mapping the intermediate residual value using the mapping function.

A signal comprising data generated by a method for decoding comprising:

• obtaining a prediction value of a current color component of a sample of a block of a picture;
• decoding a residual value for the sample;
• determining a reconstructed value for the sample from the decoded residual value and from the prediction value using both a mapping function and an inverse mapping function that is the inverse of the mapping function;
• wherein determining the reconstructed value comprises:
• mapping the prediction value with the mapping function to obtain a mapped prediction value;
• and,
• obtaining an intermediate value representative of a sum of the mapped prediction value and the residual value;
• the reconstructed value being obtained by mapping the intermediate value with the inverse mapping function.

A non-transitory information storage medium storing program code instructions for implementing a method for encoding comprising:

• obtaining a prediction value of a current color component of a sample of a block of a picture;
• determining a mapped residual value from a source value of said current color component and from the prediction value using a mapping function;
• and
• encoding the mapped residual value into a bitstream;
• wherein determining the mapped residual value comprises:
• mapping the prediction value with the mapping function to obtain a mapped prediction value;
• determining an intermediate residual value representative of a difference between the mapped prediction value and the source value;
• and
• mapping the intermediate residual value using the mapping function.

A non-transitory information storage medium storing program code instructions for implementing a method for decoding comprising:

• obtaining a prediction value of a current color component of a sample of a block of a picture;
• decoding a residual value for the sample;
• determining a reconstructed value for the sample from the decoded residual value and from the prediction value using both a mapping function and an inverse mapping function that is the inverse of the mapping function;
• wherein determining the reconstructed value comprises:
• mapping the prediction value with the mapping function to obtain a mapped prediction value;
• and,
• obtaining an intermediate value representative of a sum of the mapped prediction value and the residual value;
• the reconstructed value being obtained by mapping the intermediate value with the inverse mapping function.