Image processing method and apparatus for error-dispersion digitization without moire or spurious stripe formation
First Claim
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1. An image processing apparatus comprising:
- first calculation means for calculating a sum of density data of plural pixels existing in a first area composed of plural pixels;
second calculation means for calculation, from the sum of density data, a number of black pixels to be arranged in the first area and a difference between the sum of density data and a sum of densities of the black pixels;
conversion means for converting density data of all pixels existing in the first area into binary data, based on the number of black pixels obtained by said second calculation means;
process means for dispersing data corresponding to said difference obtained by said second calculation means into a second area which is composed of plural pixels and adjacent to the first area; and
control means for controlling said first calculation means, said second calculation means and said conversion means such that the conversion of the density data into the binary data by said conversion means is executed for each area.
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Abstract
There is provided an improvement on the error dispersion method for binary digitizing of an image, in which an area of plural pixels is digitzed, and the error into the digitizing is dispersed in a neighboring area of plural pixels. In the latter area the digitization is conducted according to the image data of plural pixels and the error data dispersed into this area.
58 Citations
11 Claims
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1. An image processing apparatus comprising:
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first calculation means for calculating a sum of density data of plural pixels existing in a first area composed of plural pixels; second calculation means for calculation, from the sum of density data, a number of black pixels to be arranged in the first area and a difference between the sum of density data and a sum of densities of the black pixels; conversion means for converting density data of all pixels existing in the first area into binary data, based on the number of black pixels obtained by said second calculation means; process means for dispersing data corresponding to said difference obtained by said second calculation means into a second area which is composed of plural pixels and adjacent to the first area; and control means for controlling said first calculation means, said second calculation means and said conversion means such that the conversion of the density data into the binary data by said conversion means is executed for each area. - View Dependent Claims (2, 3, 4, 5)
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6. An image processing apparatus comprising:
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determination means for determining, by dividing a predetermined density level into a sum of density data of plural pixels existing in a predetermined first area, a number of black pixels to be arranged in said predetermined first area; ranking means for ranking said plural pixels in a density order, on the basis of said density data; binarization means for binarizing the density data of all pixels existing in said predetermined first area, according to said number of black pixels and a rank obtained by said ranking means; correction means for correcting an error generated in the binarization for all pixels in said predetermined first area by said binarization means; and control means for controlling said determination means, said ranking means and said binarization means such that, after the binarization of all pixels in said predetermined first area is completed, the binarization of all pixels in a next area which does not overlap said predetermined first area is executed. - View Dependent Claims (7, 8, 9)
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10. An image processing apparatus comprising:
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input means for inputting image data of plural pixels existing in a predetermined area; and binarization means for binarizing said input image data of plural pixels into binary data corresponding to black and white by using a predetermined threshold value, pixel by pixel, wherein said binarization means further comprises, correction means for correcting an error generated between said input image data and said binary data, and process means for performing, in said predetermined area, a rearranging process on said binary data of plural pixels binarized by said binarization means. - View Dependent Claims (11)
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Specification