Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1991-10-31
1993-11-09
Brinich, Stephen
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358455, H04N 140
Patent
active
052608107
ABSTRACT:
This invention utilizes the fact that "a maximum density difference in a window within a predetermined range including a pixel of interest is large for a character region, and is small for a photograph region." A maximum density difference of an image within a predetermined range is calculated as a feature amount. A quantization error of pixels around a pixel of interest is calculated, and then, a correction amount is calculated by proportionally distributing the quantization error in accordance with the feature amount calculated by a feature amount calculator. The correction amount is added to an image signal of the pixel of interest to form a compensation image signal, and the compensation image signal is quantized.
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patent: 5107346 (1992-04-01), Bowers et al.
patent: 5164717 (1992-11-01), Wells et al.
R. Floyd et al., "An Adaptive Algorithm for Spatial Greyscale", Proceeding of the S.I.D., vol. 17, Second Quarter 1976, pp. 75-77.
Kanno Hiroki
Yoneda Hitoshi
Brinich Stephen
Kabushiki Kaisha Toshiba
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