Variable Brightness LCD Backlight

• US 20090146944A1
• Filed: 02/18/2009
• Published: 06/11/2009
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Kirk, David B.
• Granted Patent: US 10,043,457 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

A display for a computer system, such as an LCD, is configured to consume less power when compared to conventional designs. The display includes a screen and at least one backlight configured to illuminate the screen. An input to the at least one backlight is adjustable to produce a desired level of brightness. The input may be computed based on a generated source image and a defined constraint. An input to the display is computed based on the input to the at least one backlight and the source image. The input to the display modifies the level of brightness provided by the at least one backlight to produce a viewable image.

Claims

1. A method for displaying a display image on a backlit display device, the method comprising:

generating a source image comprised of a plurality of pixels, wherein each pixel in the source image has an associated initial brightness level;

determining a first brightness level that corresponds to the greatest initial brightness level associated with the pixels in the source image;

modifying an intensity of a backlight associated with the backlit display device based on the first brightness level to produce a modified intensity level for the backlight;

computing an LCD input image that is based on the first brightness level and the source image;

generating the display image comprising a plurality of pixels, wherein each pixel in the display image is associated with a second brightness level that is determined by adjusting the modified intensity of the backlight based on the LCD input image; and

displaying the display image on the backlit display device.

2. The method of claim 1, wherein the LCD input image is based on a first brightness bitmap associated with the source image.

3. The method of claim 1, wherein the step of modifying the intensity of the backlight comprises computing an intensity gain.

4. The method of claim 3, wherein computing the intensity gain is further based on a brightness profile of the backlight.

5. The method of claim 3, wherein the intensity gain ranges from zero to approximately one.

6. The method of claim 1, further comprising the step of generating a brightness bitmap associated with the output image, wherein the brightness bitmap is substantially similar to a brightness bitmap associated with the source image.

7. The method of claim 6, wherein the backlight comprises first and second segments, and the method includes the step of modifying an intensity of each of the segments of the backlight.

8. A computer-readable medium storing instructions that, when executed by a processor, cause a computer system to display a display image on a backlit display device, by performing the steps of:

generating a source image comprised of a plurality of pixels, wherein each pixel in the source image has an associated initial brightness level;

determining a first brightness level that corresponds to the greatest initial brightness level associated with the pixels in the source image;

modifying an intensity of a backlight associated with the backlit display device based on the first brightness level to produce a modified intensity level for the backlight;

computing an LCD input image that is based on the first brightness level and the source image;

generating the display image comprising a plurality of pixels, wherein each pixel in the display image is associated with a second brightness level that is determined by adjusting the modified intensity of the backlight based on the LCD input image; and

displaying the display image on the backlit display device.

9. The computer-readable medium of claim 8, wherein the LCD input image is based on a first brightness bitmap associated with the source image.

10. The computer-readable medium of claim 8, wherein the step of modifying the intensity of the backlight comprises computing an intensity gain.

11. The computer-readable medium of claim 10, wherein computing the intensity gain is further based on a brightness profile of the backlight.

12. The computer-readable medium of claim 10, wherein the intensity gain ranges from zero to approximately one.

13. The computer-readable medium of claim 8, further comprising the step of generating a brightness bitmap associated with the output image, wherein the brightness bitmap is substantially similar to a brightness bitmap associated with the source image.

14. The computer-readable medium of claim 13, wherein the backlight comprises first and second segments, and further comprising the step of modifying an intensity of each of the segments of the backlight.

15. A system for displaying a display image, comprising:

a display device having a backlight; and

one or more processors configured to carry out the steps of;

generating a source image comprised of a plurality of pixels, wherein each pixel in the source image has an associated initial brightness level,

determining a first brightness level that corresponds to the greatest initial brightness level associated with the pixels in the source image,

modifying an intensity of the backlight based on the first brightness level to produce a modified intensity level for the backlight,

computing an LCD input image that is based on the first brightness level and the source image,

generating the display image comprising a plurality of pixels, wherein each pixel in the display image is associated with a second brightness level that is determined by adjusting the modified intensity of the backlight based on the LCD input image, and

displaying the display image on the display device.

16. The system of claim 15, wherein the step of modifying the intensity of the backlight comprises computing an intensity gain.

17. The system of claim 16, wherein computing the intensity gain is further based on a brightness profile of the backlight.

18. The system of claim 16, wherein the intensity gain ranges from zero to approximately one.

19. The system of claim 15, further comprising the step of generating a brightness bitmap associated with the output image, wherein the brightness bitmap is substantially similar to a brightness bitmap associated with the source image.

20. The system of claim 19, wherein the backlight comprises first and second segments, and the one or more processors are further configured to modify an intensity of each of the segments of the backlight.