Patent EP0604755A1 successfully refreshed from Google Patents.
EP0604755A1
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EP
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Color matching method and apparatus
Assignee: EIDP Inc
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Filing: 1993-11-22
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Granted: —
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Expires: 2013-11-22
Abstract
Abstract A process and related apparatus for producing at least two matched color displays of a digital image using two different display devices (12,14), comprising using an adaptor (22) to convert the digital information representing the image to digital information such that the displayed image as a result of this converted digital information on one of the devices, appears the same as the image displayed on the other to an average observer when viewed under similar viewing conditions. The adaptor contains a transform LUT (28) constructed using display device modeling to generate corresponding values to preselected input digital image values to map the input color values into the color space of the display device so that image matching is achieved. One or both display devices (12,14) can be replaced by one or two printers.
Inventors
- 👤 Tony Zhongjie Liang
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 19:42
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/13; G06F3/14; G06F3/1423; G06F3/1431; H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; H04N1/603; H04N1/6052; H04N1/6055; G09; G09G; G09G2320/00; G09G2320/02; G09G2320/0271; G09G2320/0276; G09G2320/06; G09G2320/0666; G09G2320/0673
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
292 words
A method for matching the color display of at least a first device and at least a second display device, the first and second display devices having an input, comprising: (I) creating a transform LUT for converting input color values to output color values by: (1) producing a first preselected plurality of input color values; (2) using said plurality of input values to display a plurality of color patches in said first and said second display devices; (3) obtaining a colorimetric value of each of the displayed color patches in each of the displayed devices and using said colorimetric values to create a first and a second model for the first and second devices respectively correlating preselected input color values to displayed colorimetric values for each of the two devices; (4) inputting to said first and second models a second preselected plurality of color values; (5) comparing the output of the first model to the output of the second model to obtain an error signal indicative of the difference between the two output signals; (6) using the error signal to modify the input color values to the second model and again comparing the output of the first model to the output of the second model to obtain a new error signal; (7) repeating the process of steps (5) and (6) above until the error signal is a minimum; and (8) using the modified color values to create a transform LUT correlating input values to modified values; (II) using the transform LUT to transform any plurality of source color image values to corresponding new image values before inputting said new image values to the input of the second display device; and (III) displaying said new color image values on said second display device.
Claim 2
Dependent Claim
85 words
The method according to Claim 1, wherein in performing the step II, first testing every one of the plurality of source color image values; and (a) if the source color image values are included in the LUT obtaining from the LUT new image values corresponding to the source color image values; and (b) if the source color image values are not included in the LUT obtaining by interpolation from adjacent source image values in the LUT new image values corresponding to the source image values.
Claim 3
Dependent Claim
24 words
The method according to Claim 1 or 2, wherein between steps (I)(7) and (I)(8) there is the additional step of optimizing the minimum error.
Claim 4
Dependent Claim
38 words
The method according to Claim 1 or 2, wherein prior to step (I)(5), the gamut of the output color values of the first model is adjusted to be commensurate with the color values gamut of the second model.
Claim 5
Dependent Claim
22 words
The method according to Claim 2, wherein the source color image values are RGB values and the display devices are CRT displays.
Claim 6
Dependent Claim
23 words
The method according to Claim 2, wherein the source color image values are YMCK values and the display devices are 4-color printing devices.
Claim 7
Dependent Claim
42 words
The method according to Claim 2, wherein one of the display devices is a CRT display and one a 4-color proofer and wherein there is included in the color proofer a color converter for converting RGB color values to YMCK color values.
Claim 8
Dependent Claim
41 words
The method according to Claim 2, wherein one of the display devices is a CRT display and one a 4-color printer and wherein there is included in the CRT a color converter for converting YMCK color values to RGB color values.
Claim 9
Dependent Claim
235 words
Apparatus for generating a transform LUT for converting input color values to output color values, comprising: (1) digital color image values input means; (2) first and second display model means for producing each an output colorimetric tristimulus image values for input color values, each of said model means having an input and an output, the second model input connected to the input means; (3) an adder device having a first signal input connected to the input means, a second, correction error signal input, a control signal input, and an output connected to the first model input, for outputting modified color values; (4) means, connected to the output of said first and second model means, for comparing the tristimulus values output of the first and second display models and for producing an error signal; (5) means for testing the error signal to determine if said signal is a minimum error signal, and for outputting a correction error signal and a control signal to the adder, said testing means connected between said means to compare and said adder device; and (6) means also connected to the input means, the adder output, and the means for testing, for receiving the adder output and for generating a transform LUT correlating digital input color values to the modified color values appearing at the output of the adder when the means for testing determines that the error signal is a minimum.
Claim 10
Dependent Claim
14 words
The apparatus according to Claim 9, further comprising means for storing the generated LUT.
Claim 11
Dependent Claim
48 words
The apparatus according to Claim 9, further comprising a gamut mapping means for mapping output values from the second model into a color gamut commensurate to that of the first model, the gamut mapping means positioned between the output of the second model and the means to compare.
Claim 12
Dependent Claim
27 words
The apparatus according to Claim 9, further comprising an optimization means in the error testing means for determining if the minimum error is an optimum minimum error.
References Cited (Backward Citations)
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