Image analysis – Histogram processing – For setting a threshold
Patent
1989-10-02
1992-07-14
Razavi, Michael
Image analysis
Histogram processing
For setting a threshold
358429, 358456, G06K 938
Patent
active
051310597
ABSTRACT:
An image signal processor includes a first processing unit for carrying out a predetermined first quasi-tone reproduction process on an input image signal and for outputting a corresponding first processed image signal, a second processing unit for low-pass filter processing the input signal and for carrying out a predetermined second quasi-tone reproduction process on the thus low-pass filter processed input image signal and for outputting a corresponding second processed image signal, and a binarization processing unit for converting the input image signal into a binary image signal and for outputting the binary image signal. An image signal identification unit is provided for outputting an identification signal representative of a type of the input image signal based on a detected power level of the input image signal at each of at least one fixed frequency in at least one of a main scanning direction in which a read sensor for scanning image information of a document is arranged and a subscanning direction in which a read sensor is moved relative to the document. A selection unit is provided for outputting in accordance with the identification signal one of the first processed image signal of the first processing unit, the second processed image signal of the second processing unit and the binary image signal of the binarization processing unit.
REFERENCES:
patent: 4194221 (1978-12-01), Stoffel
patent: 4707745 (1987-11-01), Sakano
patent: 4821334 (1989-04-01), Ogino et al.
patent: 4920501 (1990-04-01), Sullivan et al.
patent: 4924509 (1989-03-01), Yokomizo
Kobayashi Kazuto
Sato Shin'ichi
Matsushita Graphic Communication Systems Inc.
Razavi Michael
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