| 摘要 |
PURPOSE:To extract a character area under a complex background by concentrating picture elements in a trough or a crest in accordance with the density gradation of an image to separate the character area from the background. CONSTITUTION:An area having a sharp edge exists near the border between a character and its background. The picture elements can be concentrated into the trough of the density by moving the picture elements existing on the inclined surface in the direction reversed from an arrow indicating the edge direction in accordance with the gradation of density. The edge direction decends the inclined surface of the density gradation. When the picture elements of a character are moved in the reverse direction against the arrow for instance, the picture elements are concentrated into the crest part, so that the character area can be separated from the background. When the background is dark and the character is bright near the character area, the picture elements can be concentrated into the crest part by moving the picture element in the sharp edge area in the same direction as the edge direction, so that the character area can be separated from the background.
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