Patent ID: 8320684
Filing Date: 2012-11-27
Classification: H04N

Abstract:
1. An image compressing apparatus carrying out code amount control upon JPEG2000 coding, in which a number of coding passes and a code amount for each code block generated by a MQ (arithmetic) coder are input, and a number of coding passes and a code amount are determined based on a first code amount control standard and a second code amount control standard given for each code block, comprising: a part using, for a specific code block in a designated region, the second code amount control standard to determine the number of coding passes and the code amount, and using, for code blocks not in the designated region, the first code amount control standard to determine the number of coding passes and the code amount; and wherein, according to a truncation table selected from among a plurality of truncation tables, the truncation table describes a truncation amount for each color component and for each sub-band of each level, truncation is carried out, and a total code amount is calculated; each time the calculated total code amount is compared with a target code amount; and selection of a truncation table is repeated until the calculated total code amount reaches the target code amount; and wherein the apparatus is configured to select a truncation table from a memory based on a table address, and, for each code block not in the designated region, a truncation table value is subtracted from a corresponding coding passes number, and for the code block in the designated region, a truncation table value is not subtracted from a coding passes number, a coding amount is obtained for the obtained coding passes number, the process is repeated for all the code blocks to obtain the total code amount, it is determined whether the total code amount reaches the target code amount, the process starting from selection of a truncation table is repeated when the total code amount does not reach the target code amount, and the currently selected truncation table is finally selected when the total code amount reaches the target code amount.