IMAGE PROCESSING METHOD, IMAGE PROCESSING UNIT, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To find a binary threshold for obtaining a satisfactory binary image from a grey level image.

SOLUTION: A likelihood reference value and total dispersion are found from a gray level histogram obtained from the density value of each pixel in the grey level image and a gradation conversion density value where a real density value in which the density value of each pixel in the grey level image is converted is converted for processing further. A normalization separation degree normalized to 0 to 1 is found from the likelihood reference value and the total dispersion. A normalization binary evaluation value is found from the normalization separation degree and the total dispersion, where the normalization binary evaluation value is a binary evaluation value for judging an appropriate binary threshold. It is judged that the normalization binary evaluation value found to each value of a gradation conversion parameter is appropriate. The binary threshold value as the normalization binary evaluation value in the optimum value of the gradation conversion parameter is set to be an optimum binary threshold.

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