Monitor gamma determination and correction

• US 5,910,796 A
• Filed: 05/20/1996
• Issued: 06/08/1999
• Est. Priority Date: 05/20/1996
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited, Ricoh Corporation (Ricoh Company Limited)
• Original Assignee: Ricoh Company Limited, Ricoh Corporation (Ricoh Company Limited)
• Inventors: Gormish, Michael J.
• Primary Examiner(s): CHOW, DOON Y
• Application Number:
  US08/650,478
• Time in Patent Office: 1,114 Days
• Field of Search: 345/147, 345/150, 345/153, 345/154, 345/22, 348/674, 348/675, 348/676, 348/677, 358/518, 358/519, 364/526
• US Class Current: 345/600
• CPC Class Codes: G06F 3/04897 Special input arrangements or commands for improving display capability
• CPC Class Codes: G09G 1/285 Interfacing with colour displays, e.g. TV receiver
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve

Abstract

A computer-implemented method of performing gamma correction for a display device is provided. The display device is capable of displaying images using three color components, such as red, green, and blue. A first color bar image is displayed on the display device. The first color bar image has a constant intensity for two of the color components and a linear scale of intensity along a coordinate axis for the third color component. A second color bar image is also displayed which has a constant intensity for the first two color components and a constant average intensity for the third color component. A user input is then received specifying a location on the first color bar image at which the color of the first color bar image appears to match the overall color of the second color bar image. An estimate of the gamma of the display device is determined based on the location specified by the user input. Next, a correction value is determined based on the estimate of the gamma. The second color bar image is then redisplayed using the correction value, such that the color of the second color bar image is pure gray if the estimate of the gamma was correct. The estimate of the gamma can then be utilized to provide gamma correction for the display device.

Claims

1. A method of enabling gamma correction to be performed for a display device, the display device having an input/output response characterized by a gamma, the display device capable of displaying color images using at least three color components, the method comprising the steps of:

causing the display device to display a first image, the first image characterized by a substantially constant intensity for each of a first two color components of the three color components, the first image further characterized by a substantially linear scale of intensity along a coordinate axis for a third color component of the three color components;

causing the display device to display a second image, the second image characterized by a substantially constant intensity for each of the first two color components, the second image further characterized by a substantially constant average intensity for the third color component, wherein the second image has an overall color;

receiving a user input specifying a location on the first image at which the first image appears to match the overall color of the second image; and

determining an estimate of the gamma based on the location on the first image specified by the user input.

2. The method of claim 1, further comprising the step of causing the display device to display a third image based on the correction value, such that the overall color of the third image is an indication of the gamma for the display device.

3. The method of claim 2, wherein, in the step of causing the display device to display the third image, the third image has no hue if the estimate of the gamma is substantially equal to the gamma.

4. The method of claim 1, further comprising the step of modifying the input/output response of the display device based on the estimate of the gamma, such that the display device has an effective gamma substantially equal to one (1).

5. The method of claim 1, wherein the step of causing the display device to display the second image comprises the step of generating the substantially constant average intensity of the third color component such that the third color is substantially unaffected by the gamma.

6. The method of claim 5, wherein the step of causing the display device to display the second image further comprises the step of assigning the pixels in the second image intensities which alternate by pixel between a first intensity value and a second intensity value.

7. The method of claim 1, further comprising determining a correction value based on the estimate of the gamma.

8. In a server system in communication with a client system over a geographically distributed network, the client system including a display device, a method of performing gamma correction for the display device, the method comprising the steps of:

transmitting first information from the server system to the client system, the first information to be used by the client system to cause a first image to be displayed by the display device, the first image having a substantially constant intensity for each of a first two colors, the first image further having a substantially linear scale of intensity along a coordinate axis for a third color;

the first information further to be used by the client system to cause a second image to be displayed by the display device, the second image having a substantially constant intensity for each of the first two colors, the second image further having a substantially constant average intensity for the third color, the second image further having an overall color;

the first information further to be used by the client system to cause the client system to receive a user input specifying a location on the first image at which the first image appears to match the overall color of the second image;

the first information further to be used by the client system to cause the client system to transmit to the server system information indicating the location specified by the user input;

determining an estimate of a gamma of the display device based on the information indicating the location specified by the user input;

determining a correction value based on the estimate of the gamma;

transmitting second information from the server system to the client system, the second information to be used by the client system to cause the display device to display a third image in place of the second image based on the correction value, the third image having an overall color, wherein the overall color of the third image is representative of a corrected gamma of the display device, such that the overall color of the third image is without hue if the estimate of the gamma is substantially equal to the gamma.

9. The method of claim 8, wherein the first information and the second information are included in a hypertext document.

10. The method of claim 8, wherein the first image, the second image, and the third image are generated as part of at least one World Wide Web page.

11. A program storage device readable by a machine, the program storage device tangibly embodying sequences of instructions executable by the machine to perform method steps for providing gamma correction for a display device coupled to the machine, the method steps comprising:

causing the display device to display a first image, the first image having a substantially constant intensity for each of a first two colors, the first image having a substantially linear scale of intensity for a third color with respect to position on the display device;

causing the display device to display a second image, the second image having a substantially constant intensity for each of the first two colors and having a substantially constant average intensity for the third color, wherein the second image has an overall color;

receiving a user input specifying a location on the first image at which the first image is perceived by a user to match the overall color of the second image;

determining an estimate of the gamma based on the location on the first image specified by the user input; and

determining a correction value based on the estimate of the gamma.

12. The program storage device of claim 11, the method steps further comprising the step of causing the display device to redisplay the second image based on the correction value, such that the second image indicates a degree of correctness of the gamma.

13. The program storage device of claim 12, wherein the step of causing the display device to redisplay the second image comprises the step of causing the display device to redisplay the second image such that the second image is without hue if the estimate of the gamma is equal to the gamma.

14. The program storage device of claim 11, wherein the step of causing the display device to display the second image comprises the step of determining the substantially constant average intensity of the third color to be such that the third color is substantially unaffected by the gamma.

15. The program storage device of claim 14, wherein the second image has a plurality of pixels, wherein the step of causing the display device to display the second image further comprises the step of assigning the pixels in the second image intensities which alternate by pixel between a first intensity value and a second intensity value.

16. In a computer system having a display device, a method of performing gamma correction for the display device, the display device having an input/output response substantially characterized by the equation

17. An apparatus for performing gamma correction for a display device, the display device having an input/output response characterized by a gamma, the display device capable of displaying color images using at least three color components, the apparatus comprising:

means for causing the display device to display a first image, the first image characterized by a substantially constant intensity for each of a first two color components of the three color components, the first image further characterized by a substantially linear scale of intensity along a coordinate axis for a third color component of the three color components;

means for causing the display device to display a second image, the second image characterized by a substantially constant intensity for each of the first two color components, the second image further characterized by a substantially constant average intensity for the third color component, wherein the second image has an overall color;

means for receiving a user input specifying a location on the first image at which the first image appears to match the overall color of the second image;

means for determining an estimate of the gamma based on the location on the first image specified by the user input; and

means for determining a correction value based on the estimate of the gamma.

18. The apparatus of claim 17, further comprising means for causing the display device to display a third image based on the correction value, such that the overall color of the third image is an indication of the gamma for the display device.

19. The apparatus of claim 18, wherein the means for causing the display device to display the third image comprises means for causing the display device to display the third image with no hue if the estimate of the gamma is substantially equal to the gamma.

20. The apparatus of claim 17, further comprising means for modifying the input/output response of the display device based on the estimate of the gamma, such that the display device has an effective gamma substantially equal to one (1).

21. The apparatus of claim 17, wherein the means for causing the display device to display the second image comprises means for generating the substantially constant average intensity of the third color component such that the third color is substantially unaffected by the gamma.

22. The apparatus of claim 21, wherein the means for causing the display device to display the second image further comprises means for assigning the pixels in the second image intensities which alternate by pixel between a first intensity value and a second intensity value.