Facsimile and static presentation processing – Natural color facsimile – Color correction
Patent
1996-02-08
1996-12-03
Cous, Jose L.
Facsimile and static presentation processing
Natural color facsimile
Color correction
358525, 382276, 395131, G03F 308
Patent
active
055813763
ABSTRACT:
Input device signals R.sub.s, G.sub.s, B.sub.s generated by an image input terminal are converted to colorimetric values R.sub.c, G.sub.c, B.sub.c. The colorimetric values processed by an image processing unit to generate address entries to a lookup table which stores a set of transform coefficients with which the R.sub.c, G.sub.c, B.sub.c values may be processed to convert them to C.sub.x, M.sub.x, Y.sub.x, K.sub.x colorant signals or any multi-dimensional output color space, which include but are not limited to CMYK or spectral data. Values which are not directly mapped from the table are determined using tetrahedral interpolation over a hexagonal lattice. The hexagonal lattice is formed by offsetting by a half unit every other row of one of its dimensions relative to another dimension. The offset provides closer packing of sample points that define more regular tetrahedrons to reduce relative interpolation errors. The packing also allows for easy lookup table access and simple tests to determine which tetrahedron contains a desired value.
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Color Correction Technique for Hard Copies by 4-Neighbors Interpolation Method, Kanamori Journal of Imaging Science and Technology vol. 36, No. 1 Jan./Feb. 1992 pp. 73-80.
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Basch Duane C.
Cous Jose L.
Do Anh Hong
Xerox Corporation
Zell Thomas B.
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