High-speed color saturation converter for digital color data

• US 5,315,694 A
• Filed: 08/28/1989
• Issued: 05/24/1994
• Est. Priority Date: 08/31/1988
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kasano, Akira
• Primary Examiner(s): Zimmerman, Mark K.
• Application Number:
  US07/398,948
• Time in Patent Office: 1,730 Days
• Field of Search: 364/518, 364/521, 364/526, 358/75, 358/80, 358/504, 358/506, 358/516, 358/518, 395/131
• US Class Current: 345/591
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77

Abstract

A high-speed saturation converter for a color image, comprising first R, G, and B image memories for storing digital color image data separated into R, G, and B, matrix coefficient calculating CPU for calculating two types of matrix coefficients α and β defined by the following equation based on given saturation conversion coefficient a:

α=1+2a, β=1-a;

a processor for calculating R, G, and B components r*, g*, and b* of an identical pixel when saturation conversion S*=aS is performed with respect to vector S, in an RGB color space, of saturation components corresponding to R, G, and B components of the identical pixel in the first R, G, and B image memories, in accordance with the following matrix equation defined when an intensity before and after the conversion is constant: ##EQU1## and second R, G, and B image memories for storing the R, G, and B components r*, g*, and b* calculated by the processor means in a position of the corresponding pixel.

Claims

1. A high-speed saturation converter for a color image, comprising:

first R, G, and B image memories for storing digital color image data separated into R, G, and B components, r, g, and b;

matrix coefficient calculating means for calculating two types of matrix coefficients α and

β

defined by the following equation based on a predetermined saturation conversion coefficient a;

space="preserve" listing-type="equation">α

=1+2a, β

=1-a;

processor means for calculating R, G, and B components r*, g*, and b* of a first pixel position when saturation conversion S*=aS is performed with respect to vector S, in an RGB color space, of saturation components r, g, and b of a second pixel position of said first R, G, and B image memories that corresponds to the first pixel position, in accordance with the following matrix equation defined when an intensity before and after the conversion is constant;

##EQU10## and second R, G, and B image memories for storing the R, G, and B components r*, g*, and b* calculated by said processor means in a position of the first pixel.

2. The high-speed saturation converter for a color image according to claim 1, wherein the matrix coefficient calculating means is a gate array.

3. The high-speed saturation converter for a color image according to claim 1, wherein the matrix coefficient calculating means includes storing means for storing the matrix coefficients.

4. The high speed saturation converter for a color image according to claim 1, where the processor means is a central processing unit.

5. The high speed saturation converter for a color image according to claim 1, where the processor means includes means for storing the matrix coefficients.

6. The high speed saturation converter for a color image according to claim 1, further comprising a display connected to the second imaging memories for displaying data according to the R, G, B, components of the second image memories.

7. A converter for changing a saturation of color data representing three primary colors, comprising:

means for providing r, g, and b data corresponding to the primary color data;

means for generating changeable matrix parameters α and

β

by which the saturation is defined; and

means for converting the r, g, and b data into r*, g* and b* data using a conversion matrix such that a color saturation of the r*, g*, and b* data can be changed independently of an intensity of the r*, g* and b* data according to said matrix parameters α and

β

, said conversion matrix being defined in the following relation;

##EQU11## where K in the above relation is a proportional constant defining the intensity of the r*, g* and b* data.

8. A converter according to claim 7, wherein said generating means includes:

means responsive to a given color saturation parameter a, for calculating (2a+1) to provide said matrix parameter α

; and

means for calculating (1-a) to provide said matrix parameter β

.

9. A converter according to claim 7, wherein the converting means includes means for setting the proportional constant K to substantially "1/3," so that the color saturation of the r*, g*, and b* data is changed while the intensity thereof is substantially fixed.

10. A converter for changing a hue of color data representing three primary colors, comprising:

means for providing r, g, and b data corresponding to the color data; and

means responsive to variable parameters K and θ

, for converting the r, g, and b data into r*, g*, and b* data using a conversion matrix, such that a hue of the r*, g*, and b* data can be changed independently of an intensity of the r*, g* and b* data according to said parameter θ

, said conversion matrix being defined in the following relation;

##EQU12## where the parameters K and θ

define the intensity and hue of the r*, g*, and b*, respectively.

11. A color processor for controlling a color saturation of a composite color signal including a luminance signal Y, a color-difference signal (R-Y), and a color-difference signal (B-Y), comprising:

means for converting an analog composite color signal into digital signals Y, (R-Y), and (B-Y);

means responsive to variable parameters K and a, for converting the digital signals Y, (R-Y), and (B-Y) into digital signals Y*, (R-Y)*, and (B-Y)* using a conversion matrix, such that a saturation of a color signal produced from the signals Y*, (R-Y)* and (B-Y)* can be changed independently of an intensity of the color signal according to said parameter a, said conversion matrix being defined in the following relation;

##EQU13## where k1, k2, and k3 are predetermined coefficients, and the parameters K and a define the intensity and saturation of the color signal, respectively; and

means for converting the signal Y*, (R-Y)*, and (B-Y)* into a processed composite color signal.