Image processing method and apparatus with conditional correction of error data

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United States of America Patent

PATENT NO 4958238
SERIAL NO

07319057

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ATTORNEY / AGENT: (SPONSORED)

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Abstract

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There is provided an image processing apparatus which handles an image as a digital signal, comprising: an input device to input image data indicative of a concentration of an image; a binarization circuit to binarize the input image data; a positive/negative state detection circuit to detect whether error data generated when the image data is binarized by the binarization circuit is in a positive state or a negative state; and a selector to select whether the error data generated upon binarization is to be corrected or not, on the basis of the positive or negative state of the error data. The input device has a generator to read an original and generate an analog image signal and a converter to convert the analog image signal into the digital image data. The error data is the difference between the input image data and the binary data produced by the binarization circuit. With this apparatus, an image of a good picture quality can be obtained by improving the error diffusion method as a halftone processing method. Even when portions of high and low concentrations in an original are very close to each other, the blanking phenomenon, wherein no dot is printed in the low concentration area near the boundary between those portions, and the consequent problem that the reproduced image lacks its proper content can be prevented.

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Patent Owner(s)

Patent OwnerAddress
CANON KABUSHIKI KAISHA30-2 SHIMOMARUKO 3-CHOME OHTA-KU TOKYO 146-8501

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Katayama, Akihiro Kawasaki, JP 249 4341
Ohsawa, Hidefumi Kawaguchi, JP 36 933

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