| 摘要 |
PURPOSE: To provide a method and a device for image processing capable of reproducing a satisfactory binary image even in an area with low density or an area in which density changes steeply. CONSTITUTION: Multi-level image data is supplied from image memory 10 to a binary threshold value decision means 40. The binary threshold value decision means 40 samples the density and density gradient of the picture element of the multi-level image data, and sets a parameter in accordance with the size of density gradient, and decides a binary threshold value according to a prescribed calculation formula by using the parameter and the density of the picture element. While, the image data from the image memory 10, after receivingγcorrection by aγcorrection means, is supplied to a binarization processing means. Binarization processing is applied to the binary threshold value decided by the binary threshold value decision means 40 by an error diffusion method.
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