| 摘要 |
PURPOSE:To execute the high speed by substituting a standard equal interval threshold to the first dither matrix, executing gradation correction to the threshold, adopting a system to determine the threshold of the second dither matrix and omitting a gradation correcting processing over all surface elements. CONSTITUTION:When threshold elements stored in the first dither matrix 2 (This is T.) are t11, t12, ... tnn, the threshold elements stored into the second dither matrix 4 (This is T.) are t'11, t'12, ... t'nn and a function generated by a correcting function generating means 5 is (f), the relation between two dither matrixes is given by T=f(T). By specifying a function (f) suitably, an n<2> number of the threshold element (This is represented by (t).) of the dither matrix 2 is converted to the threshold element (This is represented by (t).) of the dither matrix 4 by a look-up table 3. Thus, the gradation correction equal to execute the gradation correction to all surface elements can be executed, and since the correcting processing time may be only the element of the dither matrix, the high speed can be executed.
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