Method for encoding and method for decoding a LUT and corresponding devices
A method for encoding a LUT defined as a lattice of vertices is disclosed. At least one value is of each vertex of the lattice. The method comprises for a current vertex: predicting the at least one value of said current vertex from another value which is for example obtained from reconstructed values of neighboring vertices; and encoding in a bitstream at least one residue computed between the at least one value of the current vertex and its prediction in a bitstream.
1. A method for encoding a 3-dimensional color Look-Up Table associated with octants of an octree comprising:
encoding a split flag for a current octant indicating whether at least one of its immediate child octants is recursively encoded; and
encoding said current octant responsive to said split flag, wherein encoding said current octant comprises predicting at least one value of a vertex in said current octant from another value to obtain a prediction, and encoding a residue computed between the at least one value of the vertex and said prediction.
2. The method according to claim 1 , further comprising encoding a flag for said vertex indicating whether or not at least one residue is encoded for said vertex.
3. The method according to claim 1 , further comprising encoding a flag for each value of said vertex indicating whether a residue is encoded for said value or whether the residue is not encoded and is inferred to be zero.
4. The method of claim 1 , wherein said another value is obtained from at least one reconstructed value of a neighboring vertex.
5. The method according to claim 4 , wherein the at least one value of said vertex, the another value and the at least one reconstructed value of said neighboring vertex are color values.
6. The method according to claim 5 , wherein said color values are representative of a color transform.
7. The method according to claim 4 , wherein said at least one reconstructed value of a neighboring vertex belongs to a parent octant of the current octant.
8. A method for decoding a 3-dimensional color Look-Up Table of octants of an octree comprising:
decoding a split flag for a current octant indicating whether at least one of its immediate child octants is recursively decoded; and
reconstructing said current octant responsive to said split flag, wherein reconstructing said current octant comprises predicting at least one value of a vertex in said current octant from another value to obtain a prediction and reconstructing said at least one value of the vertex from said prediction and a decoded residue.
9. The method according to claim 8 , further comprising decoding a flag for said vertex indicating whether or not at least one residue is decoded for said vertex.
10. The method according to claim 8 , further comprising decoding a flag for each value of said vertex indicating whether a residue is decoded for said value or whether the residue is not decoded and is inferred to be zero.
11. The method of claim 8 , wherein said another value is obtained from at least one reconstructed value of a neighboring vertex.
12. The method according to claim 11 , the at least one value of said vertex, the another value and said at least one reconstructed value of said neighboring vertex are color values.
13. The method according to claim 12 , wherein said color values are representative of a color transform.
14. The method according to claim 11 , wherein said at least one reconstructed value of said neighboring vertex belongs to a parent octant of the current octant.
15. An encoder for encoding a 3-dimensional color Look-Up Table of octants comprising an interface for accessing said 3-dimensional color Lookup Table of octants and at least a processor configured to:
encode a split flag for a current octant indicating whether at least one of its immediate child octants is recursively encoded; and
encode said current octant responsive to said split flag, wherein to encode said current octant comprises predicting at least one value of a vertex in said current octant from another value to obtain a prediction and encoding a residue computed between the at least one value of the vertex and said prediction.
16. The encoder according to claim 15 , wherein the at least one processor is further configured to encode a flag for said vertex indicating whether or not at least one residue is encoded for said vertex.
17. The encoder according to claim 15 , wherein said another value is obtained from at least one reconstructed value of a neighboring vertex.
18. The encoder according to claim 17 , wherein the at least one value of said vertex, the another value and the at least one reconstructed value of said neighboring vertex are color values.
19. The encoder according to claim 18 , wherein said color values are representative of a color transform.
20. A decoder for decoding a 3-dimension color Look-Up Table of octants comprising an interface for accessing a bitstream and at least one processor configured to:
decode a split flag for a current octant indicating whether at least one of its immediate child octants is recursively decoded; and
reconstruct said current octant responsive to said split flag, wherein to reconstruct said current octant comprises predicting at least one value of a vertex in said current octant from another value to obtain a prediction and reconstructing said at least one value of the vertex from said prediction and a decoded residue.
21. The decoder according to claim 20 , wherein the at least one processor is further configured to decode a flag for said vertex indicating whether or not at least one residue is decoded for said vertex.
22. The decoder according to claim 20 , wherein said another value is obtained from at least one reconstructed value of a neighboring vertex.
23. The decoder according to claim 22 , the at least one value of said vertex, the another value and said at least one reconstructed value of said neighboring vertex are color values.
24. The decoder according to claim 23 , wherein said color values are representative of a color transform.