| 摘要 |
PURPOSE:To suppress the cost of a system, and to prevent the lowering of a throughput by obtaining an M(M>=N)-value coded half tone image from an N-value code image. CONSTITUTION:N-value coded images are divided into the blocks based on a unit area. For example, the image A is binary-coded using a dither matrix DM1, and a binary-coded image B can be obtained, and when the image B is divided into blocks, for example, based on the unit area of four by four, it is divided into blocks shown in thick lines. The number of black picture elements within each block is counted, and an M-value coded half tone image can be obtained by applying various processes on it. For example, when the number of new picture elements performs a gradation conversion shown in figure against the number of original elements, the number of the new black picture elements corresponding to a block B, the number of the original picture elements is seven, is converted to eleven. Thus, the cost of the system is suppressed at a low level, and the lowering of the throughput can be prevented. Furthermore, the occurrence of a moire in an image processing time can be eliminated.
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