Patent Number: 6,167,160

Title: Encoding and decoding methods and devices, and image processing apparatus using the same

Abstract: Coding efficiency is improved by adopting dynamic probability estimation, and the adaptation rate is adjusted by a minimum number of times by adding means for detecting a change in predicted state of encoding, thereby shortening encoding/decoding time. In an arithmetic encoding/decoding method for updating a cumulative probability when the generation frequency of a symbol to be encoded/decoded exceeds an allowable maximum value, an entropy associated with the generation state of the symbol to be encoded/decoded is calculated when the generation frequency has exceeded the allowable maximum value (S103), it is determined if the currently calculated entropy and previously calculated entropy have a significant difference (S104), and the cumulative probability is updated when it is determined that the two entropy values have the significant difference (S105).

Inventors: Osawa; Hidefumi (Kawaguchi, JP)

Assignee: Canon Kabushiki Kaisha

International Classification: G06T 9/00 (20060101); G06K 009/00 ()

Expiration Date: 12/26/2017