| 摘要 |
The color values in an image data are first modified in accordance with the forward dot gain curve of an offset printing press, next the watermark "tweak" values (i.e. the watermark signal values) are calculated for this modified image data. The calculated "tweak" values are then modified in accordance with the backward dot gain values of the printing press. The modified tweak values are then added to the original image data values. The image is then printed on the offset printing press. The result is that the "effective" watermark tweak on the printed paper is not materially affected by the dot gain curve of the printing press.
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