Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1991-04-24
1993-05-04
Brinich, Stephen
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
382 41, G06K 934
Patent
active
052086844
ABSTRACT:
A half-tone image processing system provides a density data storage unit for storing density data of each pixel of an original image. A Laplacian calculation unit, operatively connected to the density data storage unit, reads out density data from the density data storage unit. A Laplacian calculation is performed on an object pixel and on peripheral pixels around the object pixel to obtain corrected data. The Laplacian calculation is performed in such a manner that a difference in density between the object pixel and each of the peripheral pixels is calculated and all the differences are summed. A binary-coding unit operatively connected to the Laplacian calculation unit, compares the corrected data with a fixed threshold value to obtain binary-coded data indicating either black or white color in accordance with the threshold value. An error calculation unit, operatively connected to the Laplacian calculation unit and the binary-coding unit, determines a difference between the corrected data and the binary-coded data to obtain a binary-coded error therefrom. An error distribution unit, operatively connected to the error calculation unit, receives the binary-coded error and an error diffusion matrix to weight and diffuse the density data of each pixel and calculate a weighted binary-coded error of each pixel based on the corresponding coefficient. A calculation unit adds the weighted binary-coded error to the density data of each peripheral pixel and outputs the corrected density data to the density data storage unit to rewrite the original density data therein.
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Brinich Stephen
Fujitsu Limited
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