| 摘要 |
PURPOSE:To satisfactorily reproduce a binary image and a variable density image by dividing a screen into plural blocks, counting the number of picture elements which are included between prescribed two density threshold levels, deciding a binary image region and a variable density image region and processing them at every region. CONSTITUTION:A screen dividing means A divides the screen into plural blocks and a density threshold level setting means B sets at least two density threshold levels. A gradation level detecting means C detects the gradation levels of respective picture elements at every block, and compares the gradation levels of respective picture elements with above-mentioned density threshold levels at every block. A counting means D counts the number of the picture elements of the gradation levels included in the density threshold levels. A discriminating means E discriminates a binary picture region or a density picture region by the counted value. If the result of the discrimination shows the density picture area, a processing by systematic dither is executed, and if it shows the binary picture region, a simple binarization processing is executed. Thus, satisfactory gradation reproduction is attained with respect to the density picture, and deterioration of resolution can be prevented with respect to the binary picture.
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