METHOD FOR ENCODING AND DECODING IMAGES, ENCODING AND DECODING DEVICE, AND CORRESPONDING COMPUTER PROGRAMS

摘要

A method for coding includes; segmenting an image into blocks; grouping blocks into a number of subsets; coding, using an entropy coding module, each subset, by associating digital information with symbols of each block of a subset, including, for the first block of the image, initializing state variables of the coding module; and generating a data sub-stream representative of at least one of the coded subsets of blocks. Where a current block is the first block to be coded of a subset, symbol occurrence probabilities for the first current block are determined based on those for a coded and decoded predetermined block of at least one other subset. Where the current block is the last coded block of the subset: writing, in the sub-stream representative of the subset, the entire the digital information associated with the symbols during coding of the blocks of the subset, and implementing the initializing sub-step.

主权项

1. A method for coding at least one image comprising the steps of:
segmenting (C1) the image into a plurality of blocks (MB) able to contain symbols belonging to a predetermined set of symbols, grouping (C2) of blocks into a predetermined number (P) of subsets of blocks (SE1, SE2, . . . , SEk, . . . , SEP), coding (C3), by means of an entropy coding module, of each of said subsets of blocks, by associating digital information with the symbols of each block of a subset under consideration, said coding step comprising, for the first block of the image, a sub-step (C33) of initializing state variables of said entropy coding module, generation (C4) of at least one data sub-stream (F1) representative of at least one (SE1) of said coded subsets of blocks, said coding method being characterized in that: in the case where the current block is the first block to be coded of a subset under consideration, determination (C42) of probabilities of symbol occurrence for said first current block, said probabilities being those which have 20 been determined for a coded and decoded predetermined block of at least one other subset, in the case where the current block is the last coded block of the subset under consideration:
writing (C45), in the sub-stream representative of said at least subset under consideration, of the entirety of the digital information which has been associated with the symbols during the coding of the blocks of said subset under consideration,implementation (C46) of said initialization sub-step.