Enhancing dynamic ranges of images

• US 8,824,829 B2
• Filed: 11/08/2013
• Issued: 09/02/2014
• Est. Priority Date: 07/30/2007
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Rempel, Allan G., Seetzen, Helge, Ward, Gregory John, Whitehead, Lorne A., Heidrich, Wolfgang
• Primary Examiner(s): PATEL, KANJIBHAI B
• Application Number:
  US14/076,038
• Publication Number:
  US 20140064634A1
• Time in Patent Office: 298 Days
• Field of Search: 382/254, 382/263, 382/274, 382/298, 382/299, 358/3.27, 345/102, 345/690, 375/240.19, 375/240.21
• US Class Current: 382/274
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• 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 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H04N 5/20 Circuitry for controlling amplitude response
• CPC Class Codes: H04N 9/3126 for spatial light modulators in series

Abstract

Methods and apparatus according to various aspects take as input image data in a lower-dynamic-range (LDR) format and produce as output enhanced image data having a dynamic range greater than that of the input image data (i.e. higher-dynamic range (HDR) image data). In some embodiments, the methods are applied to video data and are performed in real-time (i.e. processing of video frames to enhance the dynamic range of the video frames is completed at least on average at the frame rate of the video signal).

Claims

1. A controller for use in displaying images, the controller configured to:

obtain image data;

downsample the image data to yield downsampled image data;

process the downsampled image data to both;

yield driving values for elements of a light source layer in a display; and

yield an enhancement function for use in modifying the image data to yield higher-dynamic-range image data, the higher-dynamic-range image data having at least one enhancement region comprising enhancement-region pixels;

wherein compared to the image data, the higher-dynamic-range image data comprises increased luminance values of the enhancement-region pixels in the enhancement region.

2. A controller according to claim 1 wherein, in processing the downsampled image data to yield the enhancement function, the controller is configured to further downsample the downsampled image data.

3. A controller according to claim 2 wherein, in processing the downsampled image data to yield the enhancement function, the controller is configured to process the downsampled image data to yield a binarized mask.

4. A controller according to claim 3 wherein the controller is configured to compare pixel values in the downsampled image data to a threshold to yield binary pixel values for the binarized mask.

5. A controller according to claim 3 wherein the controller is configured to upsample the binarized mask to yield a grey scale image.

6. A controller according to claim 5 wherein upsampling the binarized mask to yield the grey scale image comprises applying a blur.

7. A controller according to claim 3 comprising a linearizer arranged to linearize the image data before the controller performs the downsampling of the image data.

8. A controller according to claim 2 wherein, in processing the downsampled image data to yield the enhancement function, the controller is configured to process the downsampled image data to yield a mask and to subsequently upsample the mask wherein upsampling the mask comprises applying a DILATION operation to the mask.

9. A controller according to claim 8 wherein upsampling the mask comprises applying a gradient image as an edge stop.

10. A controller according to claim 1 wherein the controller is incorporated into a video processor chip or a display driver chip.

11. A method for displaying images, the method comprising:

obtaining image data defining an image;

downsampling the image data to yield downsampled image data;

processing the downsampled image data to both;

yield driving values for elements of a light source layer in a display; and

yield an enhancement function for use in modifying the image data to yield higher-dynamic-range image data, the higher-dynamic-range image data having at least one enhancement region comprising enhancement-region pixels wherein the enhancement-region pixels have increased luminance values as compared to corresponding pixels in the image data.

12. A method according to claim 11 wherein processing the downsampled image data to yield the enhancement function comprises further downsampling the downsampled image data.

13. A method according to claim 12 wherein processing the downsampled image data to yield the enhancement function comprises processing the downsampled image data to yield a binarized mask.

14. A method according to claim 13 comprising comparing pixel values in the downsampled image data to a threshold to yield binary pixel values for the binarized mask.

15. A method according to claim 13 comprising upsampling the binarized mask to yield a grey scale image.

16. A method according to claim 15 wherein upsampling the binarized mask to yield the grey scale image comprises applying a blur.

17. A method according to claim 13 comprising linearizing the image data before downsampling the image data.

18. A method according to claim 12 wherein processing the downsampled image data to yield the enhancement function comprises processing the downsampled image data to yield a mask and subsequently upsampling the mask wherein upsampling the mask comprises applying a DILATION operation to the mask.

19. A method according to claim 18 wherein upsampling the mask comprises applying a gradient image as an edge stop.

20. A method according to claim 11 wherein processing the downsampled image data to yield driving values for the elements of the light source layer comprises clamping the downsampled image data.

21. A method according to claim 11 wherein processing the downsampled image data to yield driving values for the elements of the light source layer comprises applying a blur filter to the downsampled image data.

22. A method according to claim 11 wherein processing the downsampled image data to yield driving values for the elements of the light source layer comprises performing an exchange operation to increase the intensity of light delivered by elements of the light source layers to areas of a second modulator that correspond to enhancement regions.