| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To apply reversible coding at a compression rate even to image data whose distribution frequency is biased such as a CG image and an image with a small number of colors while maintaining a coding efficiency for a natural image or the like. <P>SOLUTION: Pixel data are received from a signal line 206 in the raster order. A buffer 201 stores the pixel data at already coded positions. A number of color decision section 101 counts the number of colors at a plurality of pixel positions having been already coded in the vicinity of an elementary pixel. A vicinity coincidence decision section 102 generates vector information denoting whether or not pixels whose color is the same as that of the elementary pixel exist in vicinity pixels a, b, c, in the case of the number of colors is a prescribed number or below and specifying the vicinity pixel positions when the vicinity pixels with the same color as that of the elementary pixel exist. A code generating section 105 outputs each of component data of the elementary pixel in succession to a code word of the vector information in a non-compression state when the vicinity pixels with the same color as that of the target pixel do not exist. Further, when the number of colors exceeds a prescribed number, a code word from a component prediction coding section 103 is output. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
