| 摘要 |
A halftone screening method includes a method of moir+E,acu e+EE suppression, in which the input image is first screened in a trial screening module. The input image is then subtracted from the trial screened image to produce an error image which contains both the trial screen pattern and the moir+E,acu e+EE pattern introduced by the trial screening process. The error image is filtered in a lowpass filter to remove the trial screen pattern, leaving only the moir+E,acu e+EE pattern, which is then subtracted from the input image to produce a compensated image. Finally, the compensated image is then screened in a final screening module. The moir+E,acu e+EE image component of the compensated image tends to cancel the moir+E,acu e+EE pattern introduced by the final screening module so as to suppress moir+E,acu e+EE patterns in the final screened image. In two alternate embodiments, filter refinements are provided to reduce grayscale distortions and improve moir+E,acu e+EE suppression in the extreme light and shadow regions of the image.
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