| 摘要 |
PROBLEM TO BE SOLVED: To reduce a memory capacity and the frequency of access to a memory bus when compressed data are extended, and improve processing efficiency. SOLUTION: When rasterized image data are given a variable length reversible treatment on a prescribed unit-by-unit basis and stored in a compression memory, if one unit contains all white or all black data, a unit record prepared for each unit is made white NULL or black NULL. After the compression and storage of a compression code for one page's data, when the data are read and extended, judgment is made as to presence or absence of white NULL or black NULL. If either one is present, all white or all black flag is erected, and neither reading nor extension is made to the compression code for the unit. |
