Content Adaptive Backlight Power Saving Technology

• US 20160284315A1
• Filed: 03/23/2015
• Published: 09/29/2016
• Est. Priority Date: 03/23/2015
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Zhang, Yanli
• Granted Patent: US 9,805,662 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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;

performing a spatial analysis of the partial screen change to decide if the partial screen is a gradient image; and

if so, disabling phase-in of the screen change and if not 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 performing spatial analysis includes calculating the maximum difference of a pixel with neighboring pixels.

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

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

6. The method of claim 4 including determining the maximum difference based on the Y component in YUV color space.

7. The method of claim 3 including building a histogram based on maximum difference of pixels versus their neighbors.

8. The method of claim 7 including determining if a screen change is a gradient image depending on whether the majority of maximum differences fall into lower histogram bins.

9. 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;

performing a spatial analysis of the partial screen change to decide if the partial screen is a gradient image; and

if so, disabling phase-in of the screen change and if not enabling phase-in of the screen change.

10. The media of claim 9, said sequence including detecting fast changing content and enabling phase-in only if the content is changing quickly.

11. The media of claim 9, said sequence wherein performing spatial analysis includes calculating the maximum difference of a pixel with neighboring pixels.

12. The media of claim 11 wherein determining maximum difference includes determining the maximum difference in two directions.

13. The media of claim 12, said sequence including determining the maximum difference based on the V component in an HSV color space.

14. The media of claim 12, said sequence including determining the maximum difference based on the Y component in YUV color space.

15. The media of claim 11, said sequence including building a histogram based on maximum difference of pixels versus their neighbors.

16. The media of claim 15, said sequence including determining if a screen change is a gradient image depending on whether the majority of maximum differences fall into lower histogram bins.

17. An apparatus comprising:

a processor to determine whether there is a partial change of screen that affects less than all of a display screen, perform a spatial analysis of the partial screen change to decide if the partial screen is a gradient image, and if so, disable phase-in of the screen change and if not enabling phase-in of the screen change; and

a storage coupled to said processor.

18. The apparatus of claim 17, said processor to detect fast changing content and enabling phase-in only if the content is changing quickly.

19. The apparatus of claim 17, said processor calculate the maximum difference of a pixel with neighboring pixels.

20. The apparatus of claim 19, said processor to determine the maximum difference in two directions.

21. The apparatus of claim 20, said processor to determine the maximum difference based on the V component in an HSV color space.

22. The apparatus of claim 20, said processor to determine the maximum difference based on the Y component in YUV color space.

23. The apparatus of claim 19, said processor to build a histogram based on maximum difference of pixels versus their neighbors.

24. The apparatus of claim 23, said processor to determine if a screen change is a gradient image depending on whether the majority of maximum differences fall into lower histogram bins.