Ambient black level

• US 9,324,278 B2
• Filed: 06/30/2015
• Issued: 04/26/2016
• Est. Priority Date: 08/31/2010
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Ninan, Ajit, Jia, Wenhui
• Primary Examiner(s): Lee, Gene W
• Application Number:
  US14/788,396
• Publication Number:
  US 20150302804A1
• Time in Patent Office: 301 Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

Techniques for operating a display system in a wide range of ambient light conditions are provided. An intensity of ambient light on a display panel may be detected. The display panel may be illuminated by light sources in addition to the ambient light. An individual light source may be individually settable to an individual light output level. If it is determined that the luminance level of the ambient light is above a minimum ambient luminance threshold, an ambient black level may be calculated using the intensity of ambient light. Light output levels of one or more of the light sources may be elevated to first light output levels. Here, the one or more light sources may be designated to illuminate one or more dark portions of an image. The first light output levels may create a new black level equaling the determined ambient black level.

Claims

1. A method, comprising:

detecting, on a display panel, a luminance level of ambient light, the display panel being illuminated by a plurality of light sources and each individual light source in the plurality of light sources being individually settable to an individual light output level;

determining whether the luminance level of the ambient light is above a maximum ambient luminance threshold;

wherein if the luminance level of the ambient light is above the maximum ambient luminance threshold, the display panel is to operate with an intrinsic black level;

wherein the intrinsic black level being independent of the luminance level of the ambient light; and

in response to determining that the luminance level of the ambient light is not above the maximum luminance threshold, operating, by the display panel, with an ambient black level calculated based on the luminance level of the ambient light as an input variable;

wherein the method is performed by one or more computing devices.

2. The method of claim 1, wherein the luminance level of the ambient light is above a minimum ambient luminance threshold.

3. The method of claim 1, further comprising setting one or more light output levels of one or more light sources in the plurality of light sources to one or more specific light output levels, the one or more light sources in the plurality of light sources being designated to illuminate one or more dark portions of an image, and the first light output levels creating a new black level at the ambient black level in the display panel for the image.

4. The method of claim 1, comprising:

analyzing tonality information to portions of an image;

mapping the image to a new image; and

rendering the new image on the display panel.

5. The method of claim 1, further comprising operating, by the display panel, with another intrinsic black level different from the intrinsic black level.

6. The method of claim 1, further comprising:

analyzing tonality information to portions of an image;

mapping the image to a new image; and

rendering the new image on the display.

7. The method of claim 1, wherein the intensity of ambient light is the only input variable in determining the ambient black level.

8. The method of claim 1, further comprising:

in response to determining that the luminance level of the ambient light is above the maximum luminance threshold;

setting the new black level to a preconfigured high dynamic range black level so long as the intensity of ambient light is above the maximum luminance threshold; and

setting the one or more light output levels of the one or more light sources in the plurality of light sources to a highest light output levels.

9. The method of claim 1, wherein a global black level of the display panel is a preconfigured high dynamic range black level independent of the luminance level of the ambient light when the luminance level of the ambient light is not above the minimum ambient luminance threshold;

wherein the global black level is solely determined by the luminance level of the ambient light when the luminance level of the ambient light above the minimum ambient luminance threshold but not above the maximum ambient luminance threshold; and

wherein the global black level is a second preconfigured display panel black level independent of the ambient light when the luminance level of the ambient light is above the maximum ambient luminance threshold.

10. The method of claim 1, wherein a global black level of the display panel is a lowest level when the luminance level of the ambient light is not above the minimum ambient luminance threshold;

wherein the global black level is solely determined by the luminance level of the ambient light when the luminance level of the ambient light above the minimum ambient luminance threshold but not above the maximum ambient luminance threshold; and

wherein the global black level is set to the maximum ambient luminance threshold when the luminance level of the ambient light is above the maximum ambient luminance threshold.

11. The method of claim 1, wherein detecting a luminous level of ambient light includes continuously monitoring the luminance level of the ambient light using one or more light sensors.

12. The method of claim 1, wherein the ambient black level is a function of the luminance level of the ambient light.

13. The method of claim 1, wherein pixels of the display panel comprises a plurality of display portions illuminated by the plurality of light sources, and wherein each individual light source in the plurality of light sources is assigned to illuminate a different individual display portion in the plurality of display portions.

14. The method of claim 11, further comprising setting at least one of the plurality of light sources to a light output level above a minimal light output level, wherein the at least one of the plurality of light sources illuminates at least one of the plurality of display portions, and wherein the at least one of the plurality of display portions comprises pixels that are specified by image data of the image to be illuminated below the luminance level of the ambient light.

15. The method of claim 1, wherein the plurality of light sources is a plurality of backlights.

16. The method of claim 1, wherein the plurality of light sources is an array of LEDs.

17. The method of claim 1, wherein the display panel comprises a plurality of light valves that are controlled based on image data of the image.

18. The method of claim 1, wherein a dynamic range of contrast values of the display panel varies with the ambient black level.

19. The method of claim 1, wherein the intensity of ambient light is one of two or more input variables in determining the ambient black level, wherein the two or more input variable includes at least one of a point spread function of a light source and a distance between two light sources.

20. The method of claim 1, wherein the intensity of ambient light is one selected from the group consisting of a photometric luminous intensity, a luminance level, a brightness level, a weighted sum of intensity values, a weighted sum of gamma-corrected values, and a luma value.

21. A display system configured to perform the method recited in claim 1.

22. An apparatus comprising a processor and configured to perform the method recited in claim 1.

23. A computer readable storage medium, comprising software instructions, which when executed by one or more processors cause performance of the method recited in claim 1.