| 摘要 |
A method and system for efficiently generating grayscale character fonts from bi-level master character fonts decomposed into rectangles. For each filter array to be used for converting master character fonts into grayscale characters there is generated at least one summed area filter array. Each element in each summed area filter array represents the sum of the filter array elements in a corresponding subarray of the filter array. A grayscale character is generated by performing, for each rectangle in the corresponding decomposed master character, the steps of: specifying a filter array, and its corresponding summed area filter arrays; determining the pixels in the grayscale character affected by the rectangle and a set of corresponding sampling points located inside and near the rectangle; for each grayscale character pixel affected by the rectangle, performing the steps of: assigning the pixel a predefined value corresponding to a black pixel if the corresponding sampling point is located inside the rectangle, and is offset from the perimeter of the rectangle by at least one half of the extent of the filter's support; and otherwise adding to the value of the grayscale pixel a value from the summed area filter array corresponding to the intersection of the selected filter array, centered at the sampling point corresponding to the grayscale pixel, and the rectangle.
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