Image analysis – Histogram processing
Patent
1995-06-07
1998-03-03
Bost, Dwayne
Image analysis
Histogram processing
382271, 358466, G06K 938
Patent
active
057244448
ABSTRACT:
An apparatus comprising a scanner, a histogram preparation circuit, a circuit for analyzing a histogram to calculate a background density of a document and a character density, a circuit for correcting an input pixel density based on the background density and character, and a printer for forming an image based on a corrected pixel density. The histogram preparation circuit prepares a density histogram of each scanning line based on the pixel density input from the scanner, and accumulates a frequency (number of pixels) corresponding to each density. However, the frequency of the histogram, which is prepared up to the previous scanning line, is multiplied by a weighting factor in accordance with the number of scanning lines, and the frequency of the histogram of the present scanning line, is also multiplied by a weighting factor in accordance with the number of scanning lines. Thereafter, the results of the multiplication are added, and the density histogram is prepared. Therefore, the total amount of frequency data, which constitutes the density histogram prepared every scanning line, is kept constant.
REFERENCES:
patent: 4214271 (1980-07-01), Jones et al.
patent: 5289296 (1994-02-01), Yamada
patent: 5351313 (1994-09-01), Bessho
patent: 5438633 (1995-08-01), Ghaderi
patent: 5502776 (1996-03-01), Manabe
Bost Dwayne
Johnson Brian L.
Kabushiki Kaisha Toshiba
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