| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a color image compressing apparatus and a method therefor in which no noise is generated on the block boundary of an expanded image while suppressing transmission costs or medium costs with respect to an image wherein a pattern of a gradation system exists over processing unit blocks. <P>SOLUTION: A color image of the gradation system is divided into respective R, G and B planes, a primary difference with respect to data of elements in the respective planes is calculated and further, a secondary difference with respect to the primary difference is calculated to discriminate the presence/non- presence of regularity in the secondary difference. When there is regularity in the secondary difference, a reversible compression scheme of high compressibility specialized for the gradation system is used but when there is no regularity, an irreversible compression scheme is used. Thus, a color image is compressed while reducing the transmission costs or the medium costs and securing a quality in the case of expansion. <P>COPYRIGHT: (C)2004,JPO</p> |
