| 摘要 |
The invention concerns an improved image quality, as observed by a human, in digitally produced images by means of a random dither. The amplitude of the random dither, variation width, added to the image prior to its quantisation is typically the same, or greater, than the size of the colour tone step. The invention is based on that the quantity of internal noise of human vision is almost the same or greater than the increased noise produced by the random dither when the number of image tones is relatively large, for example, 60 tones. Therefore, the random dither does not produce a significant increase in noise in the image observation, but increases the number of tones which can be observed by a human, and thus improves the image quality.
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