| 摘要 |
In an image processing system containing a binary-coding apparatus for transforming multigradation image data into bigradation image data formed of only two gradations (e.g. black and white), the binary-coding apparatus includes a binary-coding section for binary-coding a target pixel into the first gradation value or the second gradation value; an error diffusion section for diffusing a binary-coding error caused during the process of binary-coding the target pixel, to its adjoining pixels not yet binary-coded; and an error diffusion matrix select section for selecting one of at least two error diffusion matrices used by the error diffusion section. The selection between matrices is rendered in accordance with an original image gradation data value of the target pixel and a binary-coding result of the target pixel. When the binary-coding result of the target pixel is the first gradation value, the error diffusion matrix select section selects an error diffusion matrix of large size when an original image gradation data value differs greatly from the first gradation value and approximates the second gradation value, so that the binary-coding error is diffused to a broader area.
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