Content adaptive backlight power saving technology

• US 9,805,662 B2
• Filed: 03/23/2015
• Issued: 10/31/2017
• Est. Priority Date: 03/23/2015
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Zhang, Yanli
• Primary Examiner(s): Thompson, James A
• Assistant Examiner(s): BEARD, CHARLES LLOYD
• Application Number:
  US14/665,352
• Publication Number:
  US 20160284315A1
• Time in Patent Office: 953 Days
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• 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 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• 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 3/34 by control of light from an independent source
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A hybrid phase-in method mitigates the flicker and rolling artifact based on screen change detection or the combination of screen change detection and image spatial analysis. It applies, for example, to solutions that involve backlight and pixel modulation including global dimming and local dimming. If it is full screen change, then no phase-in is needed and the backlight and pixel change can be applied instantly. If it is partial screen change, then content type and spatial image analysis may be used to decide whether to use phase-in or not. The spatial image analysis concept provides additional useful information besides the image brightness analysis for display backlight power saving solutions to make better tradeoffs between power saving and visual quality.

Claims

1. A method comprising:

determining whether there is a partial change of screen that affects less than all of a display screen;

building a histogram based on maximum difference of pixels versus their neighbors;

performing a spatial analysis of the partial screen change to decide if the partial screen is a gradient image that involves first color change values smaller than second color change values, including determining if a screen change is a gradient image depending on whether a majority of maximum differences in color values being smaller falling into lower histogram bins; and

if so, disabling phase-in of the screen change and if the spatial analysis indicates that the partial screen involves the second color change values larger than said first color change values, enabling phase-in of the screen change.

2. The method of claim 1 including detecting fast changing content and enabling phase-in only if the content is changing quickly.

3. The method of claim 1 wherein determining maximum difference includes determining the maximum difference in two directions.

4. The method of claim 3 including determining the maximum difference based on a V component in an HSV color space.

5. The method of claim 3 including determining the maximum difference based on the Y component in YUV color space.

6. One or more non-transitory computer readable media storing instructions executed by a processor to perform a sequence comprising:

determining whether there is a partial change of screen that affects less than all of a display screen;

building a histogram based on maximum difference of pixels versus their neighbors;

performing a spatial analysis of the partial screen change to decide if the partial screen is a gradient image that involves first color change values smaller than second color change values, including determining if a screen change is a gradient image depending on whether a majority of maximum differences in color values being smaller falling into lower histogram bins; and

if so, disabling phase-in of the screen change and if the spatial analysis indicates that the partial screen involves the second color change values larger than said first color change values, enabling phase-in of the screen change.

7. The media of claim 6, said sequence including detecting fast changing content and enabling phase-in only if the content is changing quickly.

8. The media of claim 6 wherein determining maximum difference includes determining the maximum difference in two directions.

9. The media of claim 8, said sequence including determining the maximum difference based on a V component in an HSV color space.

10. The media of claim 8, said sequence including determining the maximum difference based on the Y component in YUV color space.

11. An apparatus comprising:

a processor to determine whether there is a partial change of screen that affects less than all of a display screen, build a histogram based on maximum difference of pixels versus their neighbors, perform a spatial analysis of the partial screen change to decide if the partial screen is a gradient image that involves first color change values smaller than second color change values, wherein performing, including determining if a screen change is a gradient image depending on whether a majority of maximum differences in color values being smaller falling into lower histogram bins, and if so, disable phase-in of the screen change and if the spatial analysis indicates that the partial screen involves the second color change values larger than said first color change values, enabling phase-in of the screen change; and

a storage coupled to said processor.

12. The apparatus of claim 11, said processor to detect fast changing content and enabling phase-in only if the content is changing quickly.

13. The apparatus of claim 11, said processor to determine the maximum difference in two directions.

14. The apparatus of claim 13, said processor to determine the maximum difference based on a V component in an HSV color space.

15. The apparatus of claim 13, said processor to determine the maximum difference based on the Y component in YUV color space.