Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1983-08-11
1985-10-22
Martin, John C.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358284, 364727, H04N 521, H04N 514
Patent
active
045492123
ABSTRACT:
An improved image processing method uses a modified Walsh-Hadamard transform to remove noise and preserve image structure in a sampled image. Image signals representative of the light value of elements of the image are grouped into signal arrays corresponding to blocks of image elements. These signals are mapped into larger signal arrays such that one or more image signals appear two or more times in each larger array. The larger arrays are transformed by Walsh-Hadamard combinations characteristic of the larger array into sets of coefficient signals. Noise is reduced by modifying--i.e., coring or clipping--and inverting selected coefficient signals so as to recover processed signals--less noise--representative of each smaller signal array. The results exhibit acceptable rendition of low contrast detail while at the same time reducing certain processing artifacts characteristic of the unimproved Walsh-Hadamard block transform.
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patent: 4242705 (1980-12-01), Ebihara
patent: 4442454 (1984-04-01), Powell
"Hadamard Transform Image Coding," by W. K. Pratt, H. C. Andrews, and J. Kane, Proceedings of the IEEE, 57, 1, Jan. 1969, pp. 58-68.
"Digital Technique of Reducing Television Noise," by J. P. Rossi, Journal of the Society of Motion Picture and Television Engineers, Mar. 1978, pp. 134-140.
"Mathematical Analysis: On a generalization of the Hermite polynomials," by M. Krawtchouk, Academy of Sciences (Fr.), reported from the meeting of Sep. 23, 1929, pp. 620-622 (original in French).
Eastman Kodak Company
Martin John C.
Toth E. Anne
Woods David M.
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