Image-processing apparatus

Details Image-processing apparatus Image-processing apparatus

1989-05-23

1991-02-26

Groody, James J.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

358455, 358456, H04N 140

Patent

active

049966022

ABSTRACT:
An input gray-scale image is converted to a bilevel output signal by an image-processing apparatus with two binarizing circuits: one employing a uniform threshold and the other a dither matrix. The outputs of these circuits are selected for each pixel by deciding whether the pixel is a bilevel pixel or a gray-scale pixel. The decision is based on the maximum and minimum gray levels in a block of pixels centered on the pixel in question. Images having both bilevel and gray-scale parts can thus be binarized with clean reproduction of black-white edges.

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"Bilevel Rendition Method for Documents Including Gray-Scale and Bilevel Image", UDC 621,397.12: (741 & 7703), Nobuji Tetsutani and Hiroshi Ochi.
"A Survey of Electronic Techniques for Pictorial Image Reproduction", IEEE Transactions on Communications, vol. Co. 29, No. 12, Dec. 1981, J. C. Stoffel and J. F. Moreland.

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