Digital color correction system having gross and fine adjustment modes

• US 5,452,018 A
• Filed: 08/12/1994
• Issued: 09/19/1995
• Est. Priority Date: 04/19/1991
• Status: Expired due to Term

• Current Assignee: Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Carlucci, John, Uenaka, Kathlynn, Collier, David, Capitant, Patrice
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): HARVEY, MINSUN OH
• Application Number:
  US08/290,003
• Time in Patent Office: 403 Days
• Field of Search: 348/651, 348/649, 348/655, 348/675, 348/674, 358/518, 358/519, 358/520
• US Class Current: 348/651
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

A digital color correction system and method for correcting a color video signal representing a portion of a colored optical image by modifying the entire color space of each of the complementary colors which make up the color signal so that all objects which contain each color are modified at once. A correction means produces an output video signal having a plurality of complementary color components, each of which is related to a corresponding color component of the color video signal by a transfer function, and a modification means for independently modifying each of the transfer functions is provided. The entire color space for each color may be modified, or only selected portions of it. Thus, only objects falling within a desired range of the color space may be selectively modified.

Claims

1. A digital color corrector for correcting a color video signal representing a portion of a colored optical image thereby generating a corrected output video signal, said color video signal including a first color component signal, a second color component signal, and a third color component signal, said corrected output video signal including a first corrected color component signal, a second corrected color component signal, and a third corrected color component signal, said digital color corrector comprising:

correction circuitry for producing the corrected output video signal from the color video signal by processing the first color component signal in accordance with a first transfer function, the second color component signal in accordance with a second transfer function, and the third color component signal in accordance with a third transfer function; and

control means for controlling the correction circuitry to modify all three of the first transfer function, the second transfer function, and the third transfer function, in response to a command specifying conversion of pixels, of the color video signal, whose color component signal values determine a first color to corrected pixels, whose color component signal values determine a second color, thereby causing the correction circuitry to operate in a mode converting each pixel of the color video signal whose color component signal values determine the first color into a corrected pixel of the corrected output video signal whose color component signal values determine the second color, wherein the control means comprises limited modification means for modifying the first transfer function only for a selected range of values of the first transfer function, wherein the first color is determined by a first value of the first color component signal, a first value of the second color component signal, and a first value of the third color component signal, wherein the first value of the first color component signal is in the selected range, and wherein the limited modification means comprises;

means for changing the first transfer function for said first value in said selected range in response to said command; and

means for interpolating the first transfer function for values in said selected range other than the first value in response to said command.

2. The digital color corrector of claim 1, wherein the limited modification means includes interpolation means for modifying the second transfer function by interpolation over a second limited range of values including the first value of the second color component signal in response to the command, and modifying the third transfer function by interpolation over a third limited range of values including the first value of the third color component signal in response to the command.

3. A method for correcting a color video signal including a first color component signal, a second color component signal, and a third color component signal, by converting pixels, of the color video signal, whose color component signal values determine a first color, to corrected pixels whose color component signal values determine a second color, said method including the steps of:

(a) processing the first color component signal in correction circuitry in accordance with a first transfer function to generate a first corrected color component signal, processing the second color component signal in the correction circuitry in accordance with a second transfer function to generate a second corrected color component signal, and processing the third color component signal in the correction circuitry in accordance with a third transfer function to generate a third corrected color component signal;

(b) before performing step (a), controlling the correction circuitry in response to a control signal by automatically modifying all of the first transfer function, the second transfer function, and the third transfer function to cause the correction circuitry to operate in a mode converting each pixel of the color video signal whose color component signal values determine the first color into a corrected pixel of the corrected output video signal whose color component signal values determine the second color, wherein the first color is determined by a first value of the first color component signal, a second value of the second color component signal, and a third value of the third color component signal, and wherein said automatic modification of the first transfer function includes interpolation of values of the first transfer function in a limited selected range including said first value, in response to said control signal; and

(c) before step (b), generating the control signal in a manner so that said control signal is indicative of data determining the first color and the second color.

4. The method of claim 3, wherein the first color component signal is a red component signal, the second color component signal is a green component signal, and the third color component signal is a blue component signal, wherein step (c) includes the steps of:

selecting hue, saturation, and value parameters that determine the second color;

converting said hue, saturation and value parameters into red, green, and blue parameters that determine said second color.

5. A method for correcting a color video signal, said color video signal representing pixels of a color image and comprising a first color component signal, a second color component signal, and a third color component signal, by converting those of the pixels, whose color component signal values determine a first color, to corrected pixels, whose color component signal values determine a second color, said method including the steps of:

(a) generating a control signal specifying the first color and the second color, said first color determined by a first value of the first color component signal, a second value of the second color component signal, and a third value of the third color component signal, and said second color determined by a fourth value of the first color component signal, a fifth value of the second color component signal, and a sixth value of the third color component signal;

(b) in response to the control signal, supplying first transfer function data to a first color component correction circuit, second transfer function data to a second color component correction circuit, and third transfer function data to a third color component correction circuit, to cause said first, second, and third color component correction circuit, respectively, to implement a first transfer function, a second transfer function, and a third transfer function, wherein the first transfer function data include;

data specifying replacement of said first value with said fourth value; and

data specifying replacement of values of the first color component signal other than said first value, but in a selected range including said first value, with interpolated values; and

(c) processing the first color component signal in the first color component correction circuit to generate a first corrected color component signal, processing the second color component signal in the second color component correction circuit to generate a second corrected color component signal, and processing the third color component signal in the third color correction circuit to generate a third corrected color component signal,

wherein the first corrected color component signal, the second corrected color component signal, and the third corrected color component signal, determine said corrected pixels.

6. The method of claim 5, wherein step (a) includes the step of matching displayed ones of the pixels, whose color component signal values determine said first color to displayed reference pixels, whose color component signal values determine said second color.

7. The method of claim 5, wherein step (a) includes the steps of:

displaying a color wheel icon including a displayed reference color, where the displayed reference color is determined by hue, saturation, and value parameters of the color wheel icon;

setting the hue, saturation, and value parameters to selected values that determine the second color; and

processing the selected values of the hue, saturation and value parameters to convert said selected values of the hue, saturation and value parameters into red, green, and blue parameters of the control signal.

8. A system for correcting a color video signal, said color video signal representing pixels of a color image and comprising a first color component signal, a second color component signal, and a third color component signal, by converting those of the pixels, whose color component signal values determine a first color to corrected pixels, whose color component signal values determine a second color, said system including:

means for generating a control signal specifying the first color and the second color, said first color determined by a first value of the first color component signal, a second value of the second color component signal, and a third value of the third color component signal, and said second color determined by a fourth value of the first color component signal, a fifth value of the second color component signal, and a sixth value of the third color component signal;

a first color component correction circuit, including means for processing the first color component signal to generate a first corrected color component signal;

a second color component correction circuit, including means for processing the second color component signal to generate a second corrected color component signal;

a third color component correction circuit, including means for processing the third color component signal to generate a third corrected color component signal, wherein the first corrected color component signal, the second corrected color component signal, and the third corrected color component signal determine said corrected pixels;

means for supplying first transfer function data to the first color component correction circuit, second transfer function data to the second color component correction circuit, and third transfer function data to the third color component correction circuit in response to the control signal, to cause said first, second, and third color component correction circuit, respectively, to process the first color component signal in accordance with a first transfer function, to process the second color component signal in accordance with a second transfer function, and to process the third color component signal in accordance with a third transfer function, wherein the first transfer function data include;

data specifying replacement of said first value with said fourth value; and

data specifying replacement of values of the first color component signal other than said first value, but in a selected range including said first value, with interpolated values.

9. The system of claim 8, wherein the means for generating the control signal includes:

means for matching displayed ones of the pixels, whose color component signal values determine said first color to displayed reference pixels, whose color component signal values determine said second color.