US 5,218,671 A · Image color correction system and method

Abstract

A system and method for correcting errors in the colors of an image in a computer-aided design system; such errors being introduced by a process such as the production of a hard-copy of an image displayed on a graphic CRT. Tools are provided for the user to select "registered" colors and to determine, either manually or by system calculation, corrected values of such registered colors that will produce the desired image on the hard-copy. The manual selection technique provides tools for iteratively creating charts of related, but varied, color squares and sending the charts to the output device. The resulting hard-copy is compared by the user with the chart displayed on the CRT and the user's selection is processed by the system. In the other technique, the hard-copy image of such color chart is re-entered to the system through an input device and the error between the original and processed color patches is calculated and applied to determine corrected colors. Once a palette of registered and corrected colors is developed, it may be applied to correct images composed of such registered colors or to correct images composed of virtually any combination of colors. For the latter type of images, color values in the image that do not correspond to "registered" colors are corrected by creating a new 3-D color space based upon the existing registered colors and assigning a corrected value of each color as a result of the "influence" of adjacent registered colors in the created color space.

Claims27

Dependent claims

In a computer-assisted design system, a method for correcting color errors introduced in computer-generated images during a process performed on images by said computer-assisted design system including the steps of:

(a) creating a chart having a portion displaying an original color with a predetermined value of a color parameter and a plurality of other portions each displaying a color having a value of said color parameter in a manner that said color parameter values of said other portions vary incrementally from said predetermined value;
(b) performing said process on said chart to produce thereby a modified chart having modified colors in the same said portions as said portion displaying an original color and said other portions as modified by said process;
(c) examining said modified colors in said modified chart and selecting one of said modified colors that resembles said original color more than the other said modified colors resemble said original color;
(d) determining an error value in response to the difference between the value of said color parameter of said selected one of said modified colors and said predetermined value of said color parameter;
(e) identifying pixels in an image that have said predetermined value of said color parameter and adjusting the value of said color parameter of said pixels as a function of said error value;
and
(f) performing said process on said image after step (e).

4 more elements

In a computer-assisted design system having a graphic display device and a hard-copy output device a method for correcting color errors introduced in computer-generated images including the steps of:

(a) displaying on said graphic display device a chart including a group of pixels each having a predetermined value of a color parameter defining an original color and a plurality of other groups of pixels, each of said other groups having values of said color parameter that vary incrementally from said predetermined value defining a plurality of other colors;
(b) creating a hard-copy of said chart having modified colors corresponding to said original color and said other colors as modified by said creating;
(c) examining said modified colors in said hard-copy of said chart and selecting one of said modified colors that resembles said original color more than the other said modified colors resemble said original color;
(d) repeating steps (a)-(c) substituting said selected one of said modified colors for said original color;
(e) determining an error value in response to the difference between the value of said color parameter of said one of said colors obtained in step (d) and said predetermined value of said color parameter;
(f) identifying pixels in an image that have said predetermined value of said color parameter and adjusting the value of said color parameter for said pixels in said image as a function of said error value;
and
(g) creating a hard-copy of said image.

5 more elements

In a computer-assisted design system having a graphic display device, a hard-copy output device and an input device, a method for correcting color errors introduced in computer-generated images including the steps of:

(a) selecting in said computer-assisted design system an original color having a predetermined value of a color parameter;
(b) sending said original color to said output device and thereby creating a hard-copy, said hard-copy displaying a modified original color that is different from said original color as a result of said creating;
(c) entering said modified original color to said computer-assisted design system by reading said hard-copy using said input device;
(d) determining the value of said color parameter for said modified original color;
(e) determining an error value in response to the difference between the value of said color parameter of said modified original color obtained in step (d) and said predetermined value of said color parameter;
and
(f) adjusting the value of said color parameter for particular pixels in an image as a function of said error value;
and
(g) sending said image to said output device to create another hard-copy displaying said image.

6 more elements

In a computer-assisted design system having a graphic display device, a hard-copy output device, and an input device, a method for correcting color errors introduced in computer-generated images including the steps of:

(a) selecting an original color having a predetermined value of a color parameter;
(b) sending said original color to said output device and thereby creating a hard-copy, said hard-copy displaying a modified original color that is different from said original color as a result of said creating;
(c) entering said modified original color to said computer-assisted design system by reading said hard-copy using said input device;
(d) determining the value of said color parameter for said modified original color;
(e) determining an error value in response to the difference between the value of said color parameter of said modified original color obtained in step (d) and said predetermined value of said color parameter;
(f) adjusting the value of said color parameter for said original color to obtain a corrected original color;
(g) repeating steps (b)-(e) for said corrected original color to determine a second error value;
(h) determining a composite error value from said error value and said second error value;
(i) adjusting the value of said color parameter for particular pixels in an image as a function of said composite error value;
and
(j) sending said image to said output device to create another hard-copy displaying said image.

8 more elements

(a) for each of a plurality of original colors having an original value of a color parameter, determining a corrected value of said parameter that will be modified substantially to the corresponding said original value by said process;
(b) for an image composed of an array of pixels, each of said pixels having a value of said color parameter, replacing said value of said color parameter with the corresponding said corrected value for pixels having an original value of said color parameter and replacing said value of said color parameter with a corrected value being interpolated from a three-dimensional color space defined from at least one of said original values for pixels not having an original value of said color parameter;
and
(c) applying said process to said image after step (b).

1 more element

A color correcting system for correcting color errors introduced in computer-generated images in a computer-assisted design system having graphic display means for displaying an image, image input means for inputting an image into said design system and image output means for producing hard-copies of images displayed on said display means, said correcting system comprising:

first means for receiving a user selection of at least one original color having an original value of a color parameter and for sending said original color to said output means to produce a hard-copy having a modified original color with a modified original value, wherein said output means cause said modified original value to be different from said original value;
second means responsive to said input means for determining an error value as a function of the difference between said original value and said modified original value for hard-copies produced by said first means and entered through said input means and for defining a corrected color as a function of said original value and said error value;
third means for storing original colors and corresponding corrected colors for processing by a digital computer;
and
fourth means for adjusting the color parameter of an image displayed on said graphic display means by replacing the original colors of said image with the corresponding corrected colors.

2 more elements

Dependencies are inferred from the claim text.

Image color correction system and method

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Image color correction system and method

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Abstract

Claims27