| 摘要 |
When a multi-level image is recovered from a pseudo-half-tone bi-level image, a smoothing component and an edge emphasis component obtained on pixels around a specified pixel to be recovered is mixed. The edge emphasis is performed only when the monority pixels exist around the specified pixel. As to the edge emphasis, a narrow line is recovered by using a pair of windows of width of one pixel of the two sides in the edge emphasis direction to obtain an edge emphasis component of width of one pixel in the edge emphasis direction. As to the mixing, the size of the windows for smoothing and the size for the edge emphasis are made almost equal to each other. In order to prevent erroneous edge detection, edge emphasis is judged by using a region including the specified pixel and another without the specified pixel. Erroneous detection of an image of high spatial frequencies can be prevented by using four detection regions.
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