Method for encoding and decoding images, encoding and decoding device, and corresponding computer programs

A device for coding at least one image comprising:

• a partitioning module configured to segment the image into a plurality of blocks,
• a calculation module configured to group the blocks into a predetermined number of subsets of blocks,
• a coding unit configured to code, using an entropy coding module, a current block of the subsets of blocks, wherein the coding comprises:
• when the current block is a first block in an encoding order of a subset that is not the first subset of the image in the encoding order:
• determining probabilities of symbol occurrence for the current block, the probabilities being those which have been determined by coding a predetermined block of at least one other subset, wherein the predetermined block is the second block in the encoding order in the other subset,
• initializing state variables of the entropy coding module, and
• coding the current block;
• and
• a streaming generating module configured to generate at least one data sub-stream for the at least one image.

A non-transitory computer readable medium storing a computer program comprising instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

• segmenting the image into a plurality of blocks,
• grouping the blocks into a predetermined number of subsets of blocks,
• coding, using an entropy coding module, a current block of the subsets of blocks, wherein the coding comprises:
• when the current block is a first block in an encoding order of a subset which is not the first subset of the image in the encoding order:
• determining probabilities of symbol occurrence for the current block, the probabilities being those which have been determined by coding a predetermined block of at least one other subset, wherein the predetermined block is the second block in the encoding order in the other subset,
• initializing state variables of the entropy coding module, and
• coding the current block;
• and
• generating at least one data sub-stream for the at least one image.

A method for decoding a stream representative of at least one coded image, the method comprising:

• identifying in the stream a predetermined number of data sub-streams corresponding respectively to at least one subset of blocks to be decoded,
• decoding a current block in the subsets of blocks corresponding to the predetermined number of data sub-streams by using an entropy decoding module, wherein the decoding comprises:
• when the current block is a first block to be decoded of a subset which is not a first subset of the coded image in a decoding order:
• reading probabilities of symbol occurrence for the current block, the probabilities being those which have been determined by decoding a predetermined block of at least one other subset, wherein the predetermined block is the second block to be decoded in the other subset in the decoding order,
• initializing state variables of the entropy decoding module, and
• decoding the current block.

A device for decoding a stream representative of at least one coded image, comprising:

• a stream extraction module configured to identify in the stream a predetermined number of data sub-streams corresponding respectively to at least one subset of blocks to be decoded,
• a decoding unit configured to decode a current block in the subsets of blocks corresponding to the identified data sub-streams using an entropy decoding module, wherein the decoding comprises:
• when the current block is a first block to be decoded of a subset which is not a first subset of the coded image in a decoding order:
• reading probabilities of symbol occurrence for the current block, the probabilities being those which have been determined by decoding a predetermined block of at least one other subset, wherein the predetermined block is the second block to be decoded in the other subset in the decoding order,
• initializing state variables of the entropy decoding module, and
• decoding the current block.

A non-transitory computer readable medium storing a computer program comprising instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

• identifying in the stream a predetermined number of data sub-streams corresponding respectively to at least one subset of blocks to be decoded,
• decoding a current block in the subsets of blocks corresponding to the identified data sub-streams by using an entropy decoding module, wherein the decoding comprises:
• when the current block is a first block to be decoded of a subset which is not a first subset of the coded image in a decoding order:
• reading probabilities of symbol occurrence for the current block, the probabilities being those which have been determined by decoding a predetermined block of at least one other subset, wherein the predetermined block is the second block to be decoded in the other subset in the decoding order,
• initializing state variables of the entropy decoding module, and
• decoding the current block.