Image coding method and image decoding method

摘要

An image coding method for improving coding efficiency by using more appropriate probability information is provided. The image coding method includes: a first coding step of coding a first set of blocks included in a first region sequentially based on first probability information; and a second coding step of coding a second set of blocks included in a second region sequentially based on second probability information. In the first coding step, the first probability information is updated depending on data of a target block to be coded, after coding the target block and before coding a next target block. In the second coding step, the second probability information is updated depending on the first probability information updated in the first coding step, before coding the first target block.

主权项

1. An image decoding method of decoding an image having a plurality of regions each including a plurality of blocks, said image decoding method comprising:
decoding a first set of blocks included in a first region of the regions sequentially based on first probability information indicating a data occurrence probability; and decoding a second set of blocks included in a second region of the regions sequentially based on second probability information indicating a data occurrence probability, the second region being different from the first region, wherein, in said decoding of the first set of blocks, the first probability information is updated depending on data of a first target block to be decoded among the first set of blocks, after decoding the first target block and before decoding a second target block to be decoded next among the first set of blocks, in said decoding of the second set of blocks, the second probability information is updated depending on data of a third target block to be decoded among the second set of blocks, after decoding the third target block and before decoding a fourth target block to be decoded next among the second set of blocks, and in said decoding of the second set of blocks, the second probability information is further updated depending on the first probability information, before decoding a fifth target block to be decoded first among the second set of blocks, the first probability information having been updated in said decoding of the first set of blocks depending on the data of the first target block.