| 摘要 |
PURPOSE:To suppress the moire by correcting the generating position of a dither matrix for each block. CONSTITUTION:The density difference 9 between periods before and after the dither processing is equal to a phase change amount 61 obtained with multiplication of a constant carried out by a multiplier 60. Said constant is decided properly so that the difference 9 is converted into the dimension of the amount 61. Furthermore the constant can have the positive or negative value so as to cope with the adverse effect of the phase correction. In other words, the constant can be varied within a range of -90 deg.-90 deg. which is effective to elimination of moire for phase correction. The phase change amount 66 showing the density difference of phase correction applied to the m-th block and the phase change amount (decided to show the density difference of the m - 1st block) applied to the m-th block are supplied to the input of an adder 68. The sum of these two phase change amounts goes to the phase correction amount of the dither matrix of the m + 1st block.
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