| 摘要 |
PURPOSE:To correct gradation information missing at binarization by using an intermediate density level at an adjacent area so as to converter either (0 or 1) of a binarization data in the resolution area into a multivalue data. CONSTITUTION:A background exists between areas 1 and 3 having the intermediate density level. The multi-value level conversion is applied to the resolution area such as an area 2 of a black character. That is, the level of the original picture signal is lower than the threshold level in the area 2 and an intermediate level is assigned to a picture element binary-coded as 0, then no discontinuity takes place between the area 2 and the areas 1, 3 and no resolution is lowered. That is, the binarization picture signal is converted to either of multi-value levels such as lightest, darkest and halftone, and the multi-value level adjacent to the halftone area among the multi-value level signals is converted into the multi-value level of the density of the halftone area based on the comparison between the density multi-value level of the halftone area and the binarization threshold level.
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