Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1983-08-11
1985-11-12
Martin, John C.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358284, 358166, 364727, H04N 140, H04N 514
Patent
active
045531650
ABSTRACT:
An improved image processing method reduces noise in a sampled image while minimizing unintended distortion of image features. Image signals are generated representative of the light value of elements of the image. These signals are formed into signal arrays aligned to blocks of image elements. The signal arrays are transformed by a set of 4 by 4 Walsh-Hadamard functions into a corresponding set of coefficient signals. Certain of these coefficient signals represent the difference between the light value of each image element and an average light value over an image region smaller than the block being transformed. By modifying--i.e., coring or clipping--and inverting only these selected coefficient signals, artifacts related to the introduction of "false" edge-like structure are reduced in the reconstructed image. In addition, in a multi-stage processing method, the excluded coefficient signals may represent the input signals to the next stage.
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Eastman Kodak Company
Martin John C.
Toth E. Anne
Woods David M.
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