Reference color selection system

• US 5,254,978 A
• Filed: 11/23/1992
• Issued: 10/19/1993
• Est. Priority Date: 03/29/1991
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Beretta, Giordano B.
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): Mengistu, Amare
• Application Number:
  US07/980,148
• Time in Patent Office: 330 Days
• Field of Search: 340/701, 340/703, 340/799, 340/798, 358/75, 358/80
• US Class Current: 345/601
• CPC Class Codes: G01J 3/462 Computing operations in or between colour spaces; Colour management systems
• CPC Class Codes: G01J 3/52 using colour charts
• CPC Class Codes: G06F 3/04845 for image manipulation, e.g. dragging, rotation, expansion or change of colour
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77
• CPC Class Codes: G09G 5/06 using colour palettes, e.g. look-up tables
• CPC Class Codes: Y10S 715/961 Operator interface with visual structure or function dictated by intended use
• CPC Class Codes: Y10S 715/974 Slider control as on-screen object in operator interface

Abstract

A reference color selection system is provided for creating a palette of colorimetrically measured colors. Palettes of colorimetrically measured colors representing naturally occurring objects and specified using a standard device independent color specification, such as the CIE color specification, are arranged in a data base. A simple-to-use color selection user interface permits a user to retrieve, view, and modify each palette. The palette of colors is displayed in a simple arrangement on a display screen such as a color monitor. Each color is transformed into coordinates in a uniform color space, such as the CIELAB space. The user may delete colors not needed, and may create new colors for the palette by mixing two existing palette colors together. The mixing function simulates an artist'"'"'s "color wash", and is a linear interpolation, or interval scale, in the uniform color space between two end colors selected by the user. A color from the range of intermediate colors may be added by the user to the selected palette, and the new palette may be stored for future use in a wide variety of color presentation systems.

Claims

1. An interactive system for creating a modified color palette composed of a plurality of palette colors, the interactive system comprising,

a memory device for storing data;

input means for receiving operation signals from an operator;

at least one color palette data structure including at least two colorimetrically measured colors composing a color palette;

each colorimetrically measured color being defined by a set of coordinates for the colorimetrically measured color in a perceptually uniform color space;

the at least one color palette data structure being stored in the memory device;

color palette display means including a display device for displaying thereon a color mixing region, for displaying therein a plurality of mixed colors, and a color palette region, for displaying therein the plurality of palette colors composing the modified color palette, in response to the operation signals from the input means;

each of the palette colors of the modified color palette being defined by the set of coordinates for the palette color in the perceptually uniform color space;

color mixing means for selecting, in response to the operation signals, two selected mixing colors from the palette colors displayed in the color palette region, and for generating the plurality of mixed colors from the two selected mixing colors;

the two selected mixing colors and the plurality of mixed colors being displayed in the color mixing region by the color palette display means;

each selected mixing color and each mixed color being defined by the set of coordinates for the selected mixing color and the mixed color in the perceptually uniform color space;

wherein the color mixing means generates the plurality of mixed colors from the two selected mixing colors by successively varying the coordinates of the two selected mixing colors in the perceptually uniform color space by a coordinate change quantity beginning with the coordinates of one selected mixing color and ending with the coordinates of the other selected mixing color;

color palette adding means, responsive to the operation signals from the input means, for selecting one of the mixed colors displayed in the color mixing region, and for adding the mixed color to the palette colors of the modified color palette;

the mixed color added to the modified color palette being displayed in the color palette region by the color palette display means;

colro palette deletion means for selecting and deleting one of the palette colors from the modified color palette displayed in the color palette region, in response to the operation signals from the input means;

the deleted palette color being removed from the color palette region; and

modified color palette memory means, cooperatively associated with the color palette display means, for storing in the memory device the modified color palette displayed in the color palette region, in response to the operation signals received from the input means.

2. The interactive system for modifying a color palette according to claim 1 wherein the coordinate change quantity is a uniformly applied, linear quantity defined according to a fixed number of mixed colors to be displayed in the color mixing region by the color palette display means.

3. The interactive system of claim 1 further including conversion means, the conversion means including a color correction transformation computed from a colorimetrically measured color gamut of the display device;

the conversion means using the color correction transformation to convert the coordinates of the at least two colorimetrically measured colors of the color palette data structure, the plurality of palette colors composing the modified color palette, the selected mixing colors, and the plurality of mixed colors into device dependent color signals for display on the display device.

4. A method for interactively producing a color palette composed of a plurality of palette colors, the method comprising the steps of:

(a) storing in a memory device at least one color palette data structure including at least two colorimetrically measured colors composing a color palette;

each colorimetrically measured color being defined by a set of coordinates for the colorimetrically measured color in a perceptually uniform color space;

(b) selecting the at least one reference color palette data structure for modification;

(c) displaying on a display device having a display screen, in a color palette region of the screen, at least two colorimetrically measured colors of the color palette selected in step (b);

the colorimetrically measured colors of the color palette being initially included in the plurality of palette colors composing the modified color palette;

each of the palette colors of the modified color palette being defined by the set of coordinates for the palette color in the perceptually uniform color space;

(d) selecting two palette colors from the color palette region of the display screen as selected mixing colors and displaying the selected mixing colors in a color mixing region of the screen;

(e) generating a plurality of mixed colors from the two selected mixing colors by successively varying the coordinates of the two selected mixing colors in the perceptually uniform color space by a coordinate change quantity beginning with the coordinates of one selected mixing color and ending with the coordinates of the other selected mixing color;

each mixed color being defined by the set of coordinates for said mixed color in the perceptually uniform color space;

(f) displaying the plurality of mixed colors in the color mixing region;

(g) selecting one of the plurality of mixed colors from the color mixing region and adding the selected mixed color to the modified color palette;

(h) displaying the selected mixed color in the color palette region of the display screen; and

(i) storing in the memory device the palette colors in the modified color palette displayed in the color palette region of the display screen.

5. The method for interactively producing a modified color palette according to claim 4 wherein the coordinate change quantity is a uniformly applied, linear quantity defined according to a fixed number of mixed colors to be displayed in the color mixing region.

6. The method of claim 4 further including, prior to displaying in steps (c), (d), (f) and (h), the step of converting each of the coordinates of the at least two colorimetrically measured colors of the reference color palette, the plurality of palette colors composing the modified color palette, the selected mixing colors, and the plurality of mixed colors into device dependent color signals for display on the display device;

the converting step using a color correction transformation computed from a colorimetrically measured color gamut of the color display device.