| 摘要 |
PURPOSE: To highly precisely separate the region of a dot photograph and a character region by obtaining the edge density distribution for respective blocks and judging and dispersion of the edge density. CONSTITUTION: A picture processing part IPU applies differentiation to a picture and a central processing part CPU extracts a picture element whose differential quotient is more than a prescribed one as an edge. IPU divides the picture into the areas (operation blocks) of prescribed size, and CPU obtains edge density for the respective operation blocks. The area consisting of the blocks where the dispersion of edge density is smaller than the prescribed value is set to be the dot photograph area after quantization. CPU calculates density averages for the respective operation blocks on an original picture and the density histogram of the whole pictures is calculates on the density averages. CPU evaluates the average density of the respective picture blocks after quantization, and considers the area consisting of the block whose dispersion of density level is smaller than the prescribed value to be a continuous gradation photograph area. |
