Backlight dimming and LCD amplitude boost

• US 8,044,923 B1
• Filed: 12/12/2007
• Issued: 10/25/2011
• Est. Priority Date: 12/11/2002
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Lew, Stephen D., Ogrinc, Michael A.
• Primary Examiner(s): Eisen; Alexander
• Assistant Examiner(s): MARINELLI, PATRICK
• Application Number:
  US11/955,279
• Time in Patent Office: 1,413 Days
• Field of Search: 345204-215, 345690-699, 345 76-104, 3151691-1694
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• 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 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3685 Details of drivers for data electrodes

Abstract

Embodiments of the present invention generally provide m Methods and apparatus for reducing power consumption of backlit displays are described. Power consumption is reduced by dimming backlighting by a first scale factor and boosting pixel values by a second scale factor to compensate for the dimming. The scale factors may be constant values. Alternately, one or both of the scale factors may be determined based on pixel values for one or more frames to be displayed and/or one or more frames that have been displayed. For example, scale factors may be calculated based on an average linear amplitude of one or more frames of pixel values or from a maximum pixel value of one or more frames of pixel values. A graphical processing system is described including an integrated circuit capable of transforming a pixel value from a gamma-compensated space to a linear space.

Claims

1. A method for reducing power consumption of a display, the method comprising:

dimming a backlight of the display by a first scale factor, wherein the first scale factor is a constant value for a frame of pixels to be displayed on the display;

calculating an average value for the frame of pixels to be displayed on the display by calculating a linear amplitude for each pixel in the frame of pixels to generate calculated linear amplitudes, accumulating the calculated linear amplitudes to generate accumulated linear amplitudes, and normalizing the accumulated linear amplitudes to generate the average value for the frame of pixels;

calculating a second scale factor based on the calculated average value and the first scale factor; and

for each pixel in the frame, increasing a value of the pixel by the second scale factor.

2. The method of claim 1, wherein the average value is an average of linear luminance values.

3. The method of claim 1, further comprising compensating for gamma correction of the frame of pixels.

4. A non-transitory computer-readable storage medium storing instructions that when executed by a processor cause the processor to reduce power consumption of a display, by performing the steps of:

dimming a backlight of the display by a first scale factor, wherein the first scale factor is a constant value for a frame of pixels to be displayed on the display;

calculating an average value for the frame of pixels to be displayed on the display by calculating a linear amplitude for each pixel in the frame of pixels to generate calculated linear amplitudes, accumulating the calculated linear amplitudes to generate accumulated linear amplitudes, and normalizing the accumulated linear amplitudes to generate the average value for the frame of pixels;

calculating a second scale factor based on the calculated average value and the first scale factor; and

for each pixel in the frame, increasing a value of the pixel by the second scale factor.

5. The computer-readable storage medium of claim 4, wherein the average value is an average of linear luminance values.

6. The computer-readable storage medium of claim 4, further comprising compensating for gamma correction of the frame of pixels.

7. A computing device configured for graphical processing, the computing device comprising:

a memory for storing instructions; and

an integrated circuit configured to execute the instructions and cause a reduction in power consumption of a display, by performing the steps of;

dimming a backlight of the display by a first scale factor, wherein the first scale factor is a constant value for a frame of pixels to be displayed on the display;

calculating an average value for the frame of pixels to be displayed on the display by calculating a linear amplitude for each pixel in the frame of pixels to generate calculated linear amplitudes, accumulating the calculated linear amplitudes to generate accumulated linear amplitudes, and normalizing the accumulated linear amplitudes to generate the average value for the frame of pixels;

calculating a second scale factor based on the calculated average value and the first scale factor; and

for each pixel in the frame, increasing a value of the pixel by the second scale factor.

8. The computing device of claim 7, wherein the average value is an average of linear luminance values.

9. The computing device of claim 7, wherein the integrated circuit is further configured to compensate for gamma correction of the frame of pixels.