| 摘要 |
PURPOSE:To decide images with high accuracy by performing orthogonal transformation for each block to obtain the average density value difference between adjacent blocks as well as the edge direction in a block and deciding a halftone spot area and a character area. CONSTITUTION:The original picture data 201 is inputted to a Hadamard transforming part 202 for each (4X4)-picture element block and undergoes the orthogonal transformation for each block. A coefficient Y11 obtained after said transformation is given to an average value difference detecting part 206 via a 1-block delay part 203. Thus the average density value difference is obtained between blocks. A segmentation part 208 sorts image data into four categories according to the edge direction of the input block. Then a deciding part 212 decides whether the image data means a halftone spot area or a character area based on the average density value difference and the edge direction in the block. |
