Displaying images on local-dimming displays

• US 10,121,454 B2
• Filed: 02/17/2017
• Issued: 11/06/2018
• Est. Priority Date: 06/21/2010
• 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): Nguyen, Chanh
• Assistant Examiner(s): Truong, Nguyen H
• Application Number:
  US15/435,677
• Publication Number:
  US 20170162173A1
• Time in Patent Office: 627 Days
• CPC Class Codes: G06T 2207/20212 Image combination
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• 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 2340/02 Handling of images in compressed format, e.g. JPEG, MPEG
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression

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.

Claims

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

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 values from the second image data component to generate the 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 driving value calculator configured to normalize the second image data component.

3. Apparatus according to claim 2, 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.

4. Apparatus according to claim 3, wherein the representative value comprises a maximum value, mean value, average value, median value, or percentile value.

5. Apparatus according to claim 3, wherein the driving value calculator is configured to clip the values of the second image component to the representative value.

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

7. Apparatus according to claim 1, wherein the first image data comprises a tone map and 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 map according to the estimated light field.

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

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

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

11. 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;

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 values from the second image data component to generate the high-dynamic range image;

extracting 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

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.

12. A method according to claim 11, comprising clipping values of the second image data to a reference value.

13. A method according to claim 11, wherein the second image data has a resolution lower than a resolution of the first image data.

14. A method according to claim 11, wherein generating the second driving signals comprises linearizing the second image data component.

15. A method according to claim 11, wherein generating the first driving signals comprises applying a sharpening filter to the first image data component.

16. A method according to claim 11, wherein generating the first driving signals comprises applying a color correction to the first image data component.

17. 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

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 values from the second image data component to generate the 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.