Displaying images on local-dimming displays

Patent metadata

Field	Value
Publication number	US-9576555-B2
Application number	US-201113704688-A
Country	US
Kind code	B2
Filing date	Jun 20, 2011
Priority date	Jun 21, 2010
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

Displays, display components, image and video processing apparatus and related methods are described. A method for driving local-dimming displays comprises generating control values for driving pixels of a spatial light modulator from one image data component and generating control values for driving backlight elements from a second image data component. The first and second image data components may respectively comprise a tone map and a ratio image. Control values for the spatial light modulator and/or backlight may be obtained using cost effective hardware.

First claim

The invention claimed is:

1. Apparatus for driving a local-dimming display comprising a backlight and a spatial light modulator, the backlight comprising a plurality of individually-controllable elements, the apparatus comprising:
a decoder configured to:
receive, from an encoder, image data comprising (i) a first image data component comprising a low-dynamic range version of an image; and (ii) a second image data component comprising values that can be used to modify the low-dynamic range version of the image to recover a high-dynamic range version of the image, wherein the low-dynamic range version of the image is a tone-mapped image of the high-dynamic range version of the image, and wherein the values that can be used to modify the low-dynamic range version of the image are linearized ratio data; and
extract, from the image data, the first image data component and the second image data component;

a first system configured to generate, using the first image data component and without using the high-dynamic range version of the image, first driving signals for the spatial light modulator; and
a second system configured to:
combine the tone-mapped image and the linearized ratio data by multiplying values in the tone-mapped image by corresponding values in the linearized ratio data to generate a high-dynamic range image;
extract luminance values of the high-dynamic range image;
down-sample the luminance values of the high-dynamic range image to generate down-sampled data and
generate, using the second image data component and without using the high-dynamic range version of the image, second driving signals for controlling the individually controllable elements of the backlight by generating the second driving signals based on the down-sampled data.

2. Apparatus according to claim 1 wherein the second system comprises a downsampler configured to down-sample the luminance values of the high-dynamic range image to generate down-sampled data.

3. Apparatus according to claim 1 wherein the second system comprises a driving value calculator configured to normalize the second image data component.

4. Apparatus according to claim 3 wherein the driving value calculator is configured to normalize the second image data component by dividing values of the second image data by a representative value.

5. Apparatus according to claim 4 wherein the representative value comprises a maximum value, mean value, average value, median value, or percentile value.

6. Apparatus according to claim 4 wherein the driving value calculator is configured to clip the values of the second image component to the representative value.

7. Apparatus according to claim 1 wherein the second system comprises a linearizer.

8. Apparatus according to claim 1 wherein the first system comprises:
a light field simulator configured to generate an estimated light field that would be produced at the spatial light modulator upon applying the second driving signals to drive the backlight; and
a tone map modifier configured to modify the tone-mapped image according to the estimated light field.

9. Apparatus according to claim 1 wherein the second image data component has a resolution lower than a resolution of the first image data component.

10. Apparatus according to claim 1 wherein the first system comprises a color correction stage.

11. Apparatus according to claim 1 wherein the first system comprises a sharpening filter.

12. Apparatus according to claim 1 , wherein the first system is further configured to generate the first driving signals based on the second image data component.

13. A method for driving a local-dimming display comprising a backlight and a spatial light modulator, the backlight comprising a plurality of individually-controllable elements, the method comprising:
obtaining, from an encoder, image data comprising (i) a first image data component comprising a low-dynamic range version of an image; and (ii) a second image data component comprising values that can be used to modify the low-dynamic range version of the image to recover a high-dynamic range version of the image, wherein the low-dynamic range version of the image is a tone-mapped image of the high-dynamic range version of the image, and wherein the values that can be used to modify the low-dynamic range version of the image are linearized ratio data;
extracting, from the image data, the first image data component and the second image data component;
generating, using the first image data component and without using the high-dynamic range version of the image, first driving signals for the spatial light modulator;
combining the tone-mapped image and the linearized ratio data by multiplying values in the tone-mapped image by corresponding values in the linearized ratio data to generate a high-dynamic range image;
extracting luminance values of the high-dynamic range image;
down-sampling the luminance values of the high-dynamic range image to generate down-sampled data; and
generating, using the second image data component and without using the high-dynamic range version of the image, second driving signals for controlling the individually controllable elements of the backlight by generating the second driving signals based on the down-sampled data.

14. A method according to claim 13 comprising clipping values of the second image data to a reference value.

15. A method according to claim 13 wherein the second image data component has a resolution lower than a resolution of the first image data component.

16. A method according to claim 13 wherein generating the second driving signals comprises linearizing the second image data component.

17. A method according to claim 13 wherein generating the first driving signals comprises applying a sharpening filter to the first image data component.

18. A method according to claim 13 wherein generating the first driving signals comprises applying a color correction to the first image data component.

19. A display apparatus comprising:
a backlight comprising a plurality of individually controllable elements;
a spatial light modulator configured to receive light from the plurality of individually controllable elements of the backlight;
a decoder configured to:
receive, from an encoder, image data comprising (i) a first image data component comprising a low-dynamic range version of an image; and (ii) a second image data component comprising values that can be used to modify the low-dynamic range version of the image to recover a high-dynamic range version of the image, wherein the low-dynamic range version of the image is a tone-mapped image of the high-dynamic range version of the image, and wherein the values that can be used to modify the low-dynamic range version of the image are linearized ratio data; and
extract, from the image data, first image data component and the second image data component;

a first system configured to generate, using the first image data component and without using the high-dynamic range version of the image, first driving signals for the spatial light modulator; and
a second system configured to:
combine the tone-mapped image and the linearized ratio data by multiplying values in the tone-mapped image by corresponding values in the linearized ratio data to generate a high-dynamic range image;
extract luminance values of the high-dynamic range image;
down-sample the luminance values of the high-dynamic range image to generate down-sampled data; and
generate, using the second image data component and

Assignees

• Ninan Ajit
• Jia Wenhui
• Dolby Laboratories Licensing Corp

Inventors

• Ninan Ajit
• Jia Wenhui

Classifications

• G09G3/36

  using liquid crystals · CPC title

• G09G2340/0428

  Gradation resolution change · CPC title

• G06T2207/20212

  Image combination · CPC title

• G09G2320/0242

  Compensation of deficiencies in the appearance of colours · CPC title

• H04N19/44

  Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder · CPC title