Automatic color calibration of a color reproduction system
First Claim
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1. A method of calibrating a color reproduction system including scanner and printer units defining dissimilar scanner and printer gamuts respectively, the method comprising the steps of:
- (A) providing a plurality of color patches;
(B) scanning the plurality of color patches through the scanner unit to generate a plurality of measured color values collectively defining a first color transfer function between the scanner and printer gamuts;
(C) sampling a color cube within the scanner gamut to generate a plurality of sampled scanner color values;
(D) selecting predetermined ones of the sampled scanner color values which are defined within the printer gamut;
(E) for each one of the selected sampled scanner color values, performing the steps of;
(1) linearly interpolating the measured color values to obtain an initial color value within the printer gamut corresponding to a given one of the selected sampled scanner color values; and
(2) recursively refining the initial color value using nonlinear interpolation of the measured color values until an optimal color value within the printer gamut is obtained; and
(F) generating a second color transfer function approximating the first transfer function based on the measured, sampled scanner, and optimal color values.
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Abstract
A method and apparatus for automatic color correction is described. The method and apparatus implemented technique in which a nonlinear interpolation technique is applied to a relatively small number of measured sample values generated from color image patches to provide a color lookup table having a larger number of calibration values stored therein.
160 Citations
15 Claims
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1. A method of calibrating a color reproduction system including scanner and printer units defining dissimilar scanner and printer gamuts respectively, the method comprising the steps of:
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(A) providing a plurality of color patches; (B) scanning the plurality of color patches through the scanner unit to generate a plurality of measured color values collectively defining a first color transfer function between the scanner and printer gamuts; (C) sampling a color cube within the scanner gamut to generate a plurality of sampled scanner color values; (D) selecting predetermined ones of the sampled scanner color values which are defined within the printer gamut; (E) for each one of the selected sampled scanner color values, performing the steps of; (1) linearly interpolating the measured color values to obtain an initial color value within the printer gamut corresponding to a given one of the selected sampled scanner color values; and (2) recursively refining the initial color value using nonlinear interpolation of the measured color values until an optimal color value within the printer gamut is obtained; and (F) generating a second color transfer function approximating the first transfer function based on the measured, sampled scanner, and optimal color values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer program product for use with a color reproduction system including a processor, a scanner in communication with said processor and defining a scanner gamut, and a printer in communication with said processor defining a printer gamut dissimilar from the scanner gamut, the product comprising:
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a computer useable medium having computer readable program code for providing a plurality of color patches; a computer useable medium having computer readable program code for scanning the plurality of color patches through the scanner to generate a plurality of measured color values collectively defining a first color transfer function between the scanner and printer gamuts; a computer useable medium having computer readable program code for sampling a color cube within the scanner gamut to generate a plurality of sampled scanner color values; a computer useable medium having computer readable program code for selecting predetermined ones of the sampled scanner color values which are defined within the printer gamut; a computer useable medium having computer readable program code for linearly interpolating the measured color values to obtain an initial color value within the printer gamut corresponding to a given one of the selected sampled scanner color values; and a computer useable medium having computer readable program code for recursively refining the initial color value using nonlinear interpolation of the measured color values until an optimal color value within the printer gamut is obtained; and a computer useable medium having computer readable program code for generating a second color transfer function approximating the first transfer function based on the measured, sampled scanner, and optimal color values. - View Dependent Claims (12, 13, 14, 15)
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Specification