| 摘要 |
A method of gradation reproduction including (a) taking image data of a pixel subject to transaction as observing pixel data; (b) weighting the image data with an error diffusion matrix based on an error data calculated on a previously processed neighboring pixel of the observing pixel; (c) obtaining a data of pixel neighboring the observing pixel; (d) calculating a density gradient around the observing pixel from the weighted observing pixel data and the neighboring pixel data, and determining whether or not the pixel lies in an image edge region; (e) determining a dot size by comparing the weighted observing pixel data with a threshold value corresponding to an individual dot size, and selecting a predetermined smaller dot size if the weighted observing pixel data lies in the edge region; (f) producing an output of dot data by taking dot coordinates as a standard position of the observing pixel, if the dot size data is greater than a threshold value for coordinates determination after a comparison between them; and (g) calculating an error data from the observing pixel data, the dot size data and the dot coordinates, and storing it in a storage means for use in a transaction of the succeeding pixel. Repeating the foregoing transaction controls both the dot size and dot coordinates, to realize a method of gradation reproduction that can prevent moire and texture from merging, and maintain fine transaction in the edge region.
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