| 摘要 |
PROBLEM TO BE SOLVED: To generate directionality in a tilt direction, to reduce graininess and further to improve the reproduction of thin lines, characters or the like in a dot image. SOLUTION: In a matrix area 80, a plurality of linear areas which extend in a direction tilted to row and column directions are arranged in a direction perpendicular to the direction without spaces, and the plurality of linear areas are alternatively assigned to first and second element groups 841 and 842 along an arrangement direction. One element is specified in each element group 841 and 842 and subsequently process of specifying an element farthest from specified elements, is repeated to acquire a turn-on order of dots with increase in gray level in one grayscale range and a turn-off order of dots with decrease in gray level in the remaining grayscale range, and a threshold value of each element is determined according to these orders. Thus, generated is a threshold matrix capable of reducing graininess in a dot image with directionality in the tilt direction, and improving the reproduction of characters or the like. COPYRIGHT: (C)2009,JPO&INPIT
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