IMAGE DATA CODER, ITS METHOD, AND IMAGE-PROCESSING UNIT, ITS METHOD AND STORAGE MEDIUM

摘要

PROBLEM TO BE SOLVED: To apply compression coding to an image subjected to quantization processing that is an aperiodic processing, such as the error spread method with a high efficiency. SOLUTION: In the case that image data binarized by an error spread method are compression-coded, when the data are read from a hard disk 3 and transferred to a printer 5, a CPU 1 inputs the read binary image in the unit of e.g. 8×8 pixel blocks and compares a black pixel in the pixel block with a threshold level having periodicity to allow the periodicity in the unit of blocks to be easily generated and pixels are arranged again. The image arranged again is compression-coded by the JBIG, LZ, or pack bit method that is advantageous of coding in the unit of plural pixels and the coded data are transferred to a printer 5.