| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique for suppressing generation of block distortion and efficiently encoding an image including both a gray-scale image and characters/line drawings. <P>SOLUTION: When a substitute candidate value derived from a DC component value of orthogonal conversion of a last sub-block is within a range of values of a pixel group having gray-scale properties of a sub-block of interest, a substitute value generator 105 determines as the substitute value a value such that the DC component value of the sub-block of interest is made to approximate the DC component value of the orthogonal conversion of the last sub-block. The substitute value is substituted for pixel data judged as a character line drawing in the sub-block of interest, and the resulting data are output. <P>COPYRIGHT: (C)2008,JPO&INPIT |
