Brightness control for spatially adaptive tone mapping of high dynamic range (HDR) images

Patent metadata

Field	Value
Publication number	US-10074162-B2
Application number	US-201615234377-A
Country	US
Kind code	B2
Filing date	Aug 11, 2016
Priority date	Aug 11, 2016
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

Techniques are provided for spatially adaptive tone mapping with dynamic brightness control. A methodology implementing the techniques according to an embodiment includes converting luminance data, from a received HDR image, to a logarithm domain and decomposing the converted data into a base layer, and one or more detail layers. The method also includes adjusting the layers, through shifting and scaling of the base layer and scaling of the detail layers, to map the amplitude data into a selected range. The method further includes converting the adjusted layers from the logarithm domain to a linear domain and calculating a tone compression parameter based on statistics of the adjusted log domain base layer. The statistics are associated with brightness of the received image. The method further includes applying a global tone compression function, based on the tone compression parameter, to the converted linear domain base layer to generate compressed linear domain layers.

First claim

What is claimed is:

1. A processor-implemented method for brightness control of spatially adaptive tone mapping (SATM), the method comprising:
converting, by a processor, luminance data, associated with pixels from a received image, to a logarithm domain;
decomposing, by the processor, the logarithm domain luminance data into a base layer, and one or more detail layers;
adjusting, by the processor, amplitudes of data in each of the layers, to map the amplitude data into a selected range;
converting, by the processor, the adjusted layers from the logarithm domain to a linear domain;
calculating, by the processor, a tone compression parameter based on statistics of the adjusted log domain base layer, the statistics associated with brightness of the received image; and
applying, by the processor, a global tone compression function, based on the tone compression parameter (tcp), to the converted linear domain base layer (B) to generate a compressed linear domain base layer (Bc), according to the equation Bc=(log(B+tcp)−log(tcp))/(log(1+tcp)−log(tcp)).

2. The method of claim 1 , further comprising generating compressed luminance data based on a multiplicative product of the compressed linear domain base layer and a compressed linear domain detail layer.

3. The method of claim 2 , further comprising generating a compressed output image based on scaling of red-green-blue (RGB) data from the received image by a ratio of the compressed luminance data to the luminance data from the received image.

4. The method of claim 1 , wherein the statistics associated with brightness are based on an average of samples of the adjusted log domain base layer.

5. The method of claim 1 , wherein the statistics are further associated with contrast of the received image.

6. The method of claim 5 , wherein the statistics associated with contrast are based on a difference between a selected upper percentile threshold and a selected lower percentile threshold of samples of the adjusted log domain base layer.

7. The method of claim 6 , wherein the selected upper percentile threshold is in the percentile range of 68 to 72, and the selected lower percentile threshold is in the percentile range of 28 to 32.

8. The method of claim 1 , wherein the received image is a High Dynamic Range (HDR) image.

9. A system for brightness control of spatially adaptive tone mapping (SATM), the system comprising:
a logarithm domain conversion circuit to convert luminance data, associated with pixels from a received image, to a logarithm domain;
an edge-aware filter circuit to decompose the logarithm domain luminance data into a base layer, and one or more detail layers;
an amplitude adjustment circuit to shift and scale the amplitudes of the base layer and to scale the amplitudes of the detail layers, to map the amplitude data into a selected range;
a linear-conversion circuit to convert the adjusted layers from the logarithm domain to a linear domain;
a tone compression parameter (TCP) adjustment circuit to calculate a TCP based on statistics of the adjusted log domain base layer, the statistics associated with brightness of the received image; and
a global tone compression circuit to apply a global tone compression function, based on the tone compression parameter (tcp), to the converted linear domain base layer (B) to generate a compressed linear domain base layer (Bc), according to the equation Bc=(log(B+tcp)−log(tcp))/(log(1+tcp)−log(tcp)).

10. The system of claim 9 , further comprising a compressed luminance data reconstruction circuit to generate compressed luminance data based on a multiplicative product of the compressed linear domain base layer and a compressed linear domain detail layer.

11. The system of claim 10 , further comprising an output generation circuit to generate a compressed output image based on scaling of red-green-blue (RGB) data from the received image by a ratio of the compressed luminance data to the luminance data from the received image.

12. The system of claim 9 , wherein the statistics associated with brightness are based on an average of samples of the adjusted log domain base layer.

13. The system of claim 9 , wherein the statistics are further associated with contrast of the received image.

14. The system of claim 13 , wherein the statistics associated with contrast are based on a difference between a selected upper percentile threshold and a selected lower percentile threshold of samples of the adjusted log domain base layer.

15. The system of claim 14 , wherein the selected upper percentile threshold is in the percentile range of 68 to 72, and the selected lower percentile threshold is in the percentile range of 28 to 32.

16. The system of claim 9 , wherein the received image is a High Dynamic Range (HDR) image.

17. At least one non-transitory computer readable storage medium having instructions encoded thereon that, when executed by one or more processors, result in the following operations for brightness control of spatially adaptive tone mapping (SATM), the operations comprising:
converting luminance data, associated with pixels from a received image, to a logarithm domain;
decomposing the logarithm domain luminance data into a base layer, and one or more detail layers;
adjusting amplitudes of data in each of the layers, the adjusting to shift and scale the amplitudes of the base layer and to scale the amplitudes of the detail layers, to map the amplitude data into a selected range;
converting the adjusted layers from the logarithm domain to a linear domain;
calculating a tone compression parameter based on statistics of the adjusted log domain base layer, the statistics associated with brightness of the received image; and
applying a global tone compression function, based on the tone compression parameter (tcp), to the converted linear domain base layer (B) to generate a compressed linear domain base layer (Bc), according to the equation Bc=(log(B+tcp)−log(tcp))/(log(1+tcp)−log(tcp)).

18. The computer readable storage medium of claim 17 , the operations further comprising generating compressed luminance data based on a multiplicative product of the compressed linear domain base layer and a compressed linear domain detail layer.

19. The computer readable storage medium of claim 18 , the operations further comprising generating a compressed output image based on scaling of red-green-blue (RGB) data from the received image by a ratio of the compressed luminance data to the luminance data from the received image.

20. The computer readable storage medium of claim 17 , wherein the statistics associated with brightness are based on an average of samples of the adjusted log domain base layer.

21. The computer readable storage medium of claim 17 , wherein the statistics are further associated with contrast of the received image.

22. The computer readable storage medium of claim 21 , wherein the statistics associated with contrast are based on a difference between a selected upper percentile threshold and a selected lower percentile threshold of samples of the adjusted log domain base layer.

23. The computer readable storage medium of claim 22 , wherein the selected upper percentile threshold is in the percentile range of 68 to 72, and the selected lower percentile threshold is in the percentile range of 28 to 32.

24. The computer readable storage medium of claim 17 , wherein the received image is a High Dynamic Range (HDR) image.

Assignees

• Intel Corp

Inventors

• El Mezeni Dragomir

Classifications

• G09G2300/0465

  Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness · CPC title

• G09G3/2007

  Display of intermediate tones · CPC title

• G06T2207/20208

  High dynamic range [HDR] image processing · CPC title

• G06T5/007 Primary

  Physics · mapped topic

• G06T3/40

  Scaling of whole images or parts thereof, e.g. expanding or contracting · CPC title