Method for encoding an input video comprising a luma component and two chroma components, the method comprising reshaping of said input video based on reshaping functions

1. A method comprising:

encoding an input video comprising a luma component and two chroma components represented by code words, wherein the encoding mcthod comprises:

reshaping of the input video by applying at least one piece-wise linear function to extend a range of the code words of the luma and chroma components to a full range;

encoding the reshaped input video into a bitstream; and

encoding parameters representative of the at least one piece-wise linear function as side information;

wherein reshaping of the input video depends on a targeted range of a decoded reshaped video and a range of code words representing a reconstructed video after an inverse-reshaping is applied on the decoded reshaped video.

2. The method of claim 1 , wherein the method further comprises encoding a first information data that determines the targeted range of a decoded reshaped video and a second information data that determines the range of a reconstructed video as the side information.

3. A method comprising:

decoding a reconstructed video from a bitstream, wherein the decoding comprises:

obtaining a decoded reshaped video by decoding the bitstream; and

obtaining the reconstructed video by inverse-reshaping the decoded reshaped video;

wherein the inverse-reshaping of the decoded reshaped video depends on a targeted range of the decoded reshaped video and a range of a reconstructed video after the inverse-reshaping is applied on the decoded reshaped video, wherein the inverse-reshaping increases a range of codewords representing at least one component of the decoded reshaped video.

4. The method of claim 3 , wherein the method further comprises obtaining a first information data that determines the targeted range of a decoded reshaped video and a second information data that determines the range of a reconstructed video from side information.

5. The method of claim 1 , wherein the method further comprises representing the at least one piece-wise linear function by a 1D Look-Up-Table.

6. The method of claim 2 , wherein the method further comprises checking a status of the first information data and a status of the second information data to determine if an expected status is reached;

then, if a first expected status is reached, the at least one piece-wise linear function is multiplied by a scaling factor lower than 1 and a non-null offset value is added to the at least one piece-wise linear function;

then, if a second expected status is reached, the at least one piece-wise linear function is multiplied by a scaling factor lower than 1;

then, if a third expected status is reached, the at least one piece-wise linear function is multiplied by a scaling factor equal to 1.

7. The method of claim 1 , wherein the side information is carried on using a Color Remapping Information Supplemental Enhancement Information message as specified by HEVC standard edition 2.

8. A device for encoding an input video comprising a luma component and two chroma components represented by code words, the device comprising a processor configured to:

reshape the input video by applying a piece-wise linear function to the luma component and two other piece-wise linear functions to the chroma components to extend a range of the code words to a full range;

encode the reshaped video into a bitstream; and

encode parameters representative of the piece-wise linear functions as side information;

wherein reshaping of the input video depends on a targeted range of a decoded reshaped video and a range of code words representing a reconstructed video after an inverse-reshaping is applied on the decoded reshaped video.

9. A device for decoding a reconstructed video from a bitstream, comprising a processor configured to obtain a decoded reshaped video by decoding the bitstream and to obtain the reconstructed video by inverse-reshaping the decoded reshaped video, wherein the inverse-reshaping of the decoded reshaped video depends on a targeted range of the decoded reshaped video a range of a reconstructed video after the inverse-reshaping is applied on the decoded reshaped video, wherein the inverse-reshaping increases a range of codewords representing at least one component of the decoded reshaped video.

10. A non-transitory storage medium carrying instructions of program code for executing steps of the method according to claim 1 , when the program is executed on a computing device.

11. A non-transitory storage medium carrying instructions of program code for executing steps of the method according to claim 3 , when the program is executed on a computing device.

12. The device of claim 9 , wherein the processor is further configured to obtain a first information data that determines the targeted range of a decoded reshaped video and a second information data that determines the range of a reconstructed video from side information.

13. The device of claim 9 , wherein the processor is further configured to represent at least one piece-wise linear function by a 1D Look-Up-Table.

14. The device of claim 12 , wherein the processor is further configure to check a status of the first information data and a status of the second information data in order to determine if an expected status is reached;

then, if a first expected status is reached, the piece-wise linear functions are multiplied by a scaling factor lower than 1 and a non-null offset value is added to the piece-wise linear function;

then, if a second expected status is reached, the piece-wise linear functions are multiplied by a scaling factor lower than 1;

then, if a third expected status is reached, the piece-wise linear functions are multiplied by a scaling factor equal to 1.

15. The device of claim 12 , wherein the side information is carried on using a Color Remapping Information Supplemental Enhancement Information message as specified by HEVC standard edition 2.

16. The method of claim 3 , wherein the method further comprises representing each piece-wise linear function by a 1D Look-Up-Table.

17. The method of claim 4 , wherein the method further comprises checking a status of the first information data and a status of the second information data in order to determine if an expected status is reached;

then, if a first expected status is reached, the piece-wise linear functions are multiplied by a scaling factor lower than 1 and a non-null offset value is added to the piece-wise linear function;

then, if a second expected status is reached, the piece-wise linear functions are multiplied by a scaling factor lower than 1;

then, if a third expected status is reached, the piece-wise linear functions are multiplied by a scaling factor equals to 1.