| 摘要 |
PROBLEM TO BE SOLVED: To enhance the gradation reproducibility, especially the gradation reproducibility in a low density area while maintaining the resolution. SOLUTION: A density adder section 23 sums density values of pixels included in a block consisting of pixels on an image to calculate a total density value. A quantization processing section 24 sets a quantization level to each pixel in the block among predetermined different quantization levels on the basis of the total density value. A quantization error spread section 26 adds a difference between the total density value and the sum of the quantization levels set to the pixels in the block to a density value of pixels at the outside of the block. The processing above is applied to the density of the pixels of the image to quantize each density value.
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