Patent ID: 7844120

Claim:
A method for compressing image data, comprising the steps of: dividing the image data into predetermined blocks; calculating a typical value corresponding to a density of image data of a processing target block, which is one of the predetermined blocks, if the image data of the processing target block can be reproduced by using the typical value, wherein the typical value is used as information representing the image data of the processing target block; checking whether or not there is an arrangement pattern that matches an arrangement pattern of the image data of the processing target block before the processing target block if the image data of the processing target block cannot be reproduced by using the typical value; calculating position data indicating a matching position if there is the arrangement pattern in the image data before the processing target block that matches the arrangement pattern of the image data of the processing target block, wherein the position data is used as information representing the image data of the processing target block; obtaining the arrangement pattern of the image data of the processing target block as block data if there is not a matching arrangement pattern in the image data before the processing target block; and creating compressed image data by using the typical value, the position data, or the block data as information representing the image data of each of the predetermined blocks, wherein each of the predetermined blocks is processed sequentially, and wherein each of the foregoing steps is performed by a computer.