| 摘要 |
PURPOSE: To provide the mask so as not to cause a processing shadow unpleasant to eyes in the case of converting a gray scale digital image into a half-tone image. CONSTITUTION: A half-tone mask is configured by an N×M matrix (figure shows an example of 13×9) corresponding to a digital image (part of a digital image) so as to make the mask matrix in cross reference with (part of) an original image. A different threshold level for gray scale/half tone conversion is assigned to each coordinate of the mask matrix. That is, while deciding each coordinate sequentially according to a fraction resulting from an integer multiple of a numeral for 2-dimension application to the golden section, a series of integers 0 to K (K is a number less than M×N by 1) each acting like a threshold level to each coordinate. Thus, a series of the threshold levels are distributed and a low frequency processing shadow unpleasant to eyes is not caused in a half-tone image after conversion.
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