| 摘要 |
PURPOSE:To prevent the production of texture pattern and the reduction in the resolution while ensuring gradation number by making a basic density pattern correspondent to an input picture element so as the change each threshold level of the pattern. CONSTITUTION:A picture inputted from a photoelectric converter 1 is compared with a threshold pattern matrix 2, then an output dot pattern is generated from a pattern generator 3 and the pattern is visualized by a printer 4. In this case, in the gradation expression, the density pattern of mXn dots being a basic value is made correspondent to one input picture element and each threshold level of the density pattern is made varied depending on the position of the input picture element. That is, a 2X2 density pattern matrix C2 is applied to an original picture C1 by 4X4 picture elements and its density pattern is changed depending on the position of the original picture. Thus, the required gradation number is ensured and the reduction in the resolution and the occurrence of a texture pattern are prevented.
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