Apparatus for thresholding an image signal

Details Apparatus for thresholding an image signal Apparatus for thresholding an image signal

1989-01-24

1990-04-17

Britton, Howard W.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

358454, 358457, H04N 1032

Patent

active

049185438

ABSTRACT:
This invention relates to an apparatus for converting a grayscale image to a bitonal image which provides improved tonal rendition with minimal loss of resolution. The invention attenuates the low spatial frequency component of the digital image and uses a similarly attenuated thresholder to convert the image to a bitonal image. When used with a dither type thresholder, this technique allows for simultaneous "continuous tone" and "line art" thresholding with minimal circuit complexity.

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