Image analysis – Color image processing – Color correction
Patent
1995-04-17
1997-09-09
Razavi, Michael T.
Image analysis
Color image processing
Color correction
358523, 358525, G03F 308
Patent
active
056664362
ABSTRACT:
The present invention is a method and apparatus for transforming source images to output images. It performs color transformations using a lookup table and a hashing circuit for referencing entries in the lookup table. The index generated by the hashing circuit is dependent on a first color value. A color encoding circuit is coupled to the lookup table for generating an encoded color value dependent on the first color value. The index produced by the hashing circuit is further dependent upon response characteristics of the human eye. The hashing circuit generates indexes referencing widely separated entries in the plurality of entries of the lookup table when first color values have small differences in value. A comparing circuit is coupled to the lookup table and the color encoding circuit for comparing the entry of the lookup table and the encoded color value to determine a match. A color calculation circuit is coupled to the lookup table for generating a second color value dependent on the first color value. The color calculation circuit generates the second color value when a match does not occur. The second color value is also stored in the entry of the lookup table. When a match does occur, the lookup table outputs the second color value instead of calculating a new second color value. In the preferred embodiment of the present invention, the hashing circuit comprises a plurality of lookup tables and a logic circuit coupled to the plurality of lookup tables for generating the index.
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Chang Jon
Electronics for Imaging
Razavi Michael T.
LandOfFree
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