| 摘要 |
PROBLEM TO BE SOLVED: To quantize colors of a digital image in a color space by sequentially dividing the color space and in several steps into several blacks, including partial sets of image colors. SOLUTION: In every step, the variance is decided for the color sets in a block and in a prescribed number of directions. Then a covariance matrix is decided to described the color sets in the block, and the variance value of color sets are calculated in a relative direction in a variance calculation step. In another step, the block is divided into two blocks according to the detected maximum variance. In such a quantization method, a color synthetic set undergoes a prescribed test and the block corresponding to the set is connected again for the refining. Then this method is used for preparing the digital image data to an interpretation processing operation, such as an OCR or layout analysis.
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