Apparatus and Method for Rendering High Dynamic Range Images for Standard Dynamic Range Display

• US 20090027558A1
• Filed: 07/27/2007
• Published: 01/29/2009
• Est. Priority Date: 07/27/2007
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Mantiuk, Rafal, Daly, Scott James
• Granted Patent: US 8,330,768 B2
• Time in Patent Office: Days
• US Class Current: 348/673
• CPC Class Codes: H04N 1/4072 dependent on the contents of the original
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence
• CPC Class Codes: H04N 5/20 Circuitry for controlling amplitude response
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

The method, system and apparatus embodiments of the present invention provide for rendering original images having high dynamic range into display images having lower dynamic range while retaining a visual quality of rendered images comparable to the original or reference images. Tone-mapping parameters are applied to the display images and are iteratively adjusted in order to reduce the differences between the conditioned original image and the conditioned display image.

Claims

1. A method of image rendering comprising:

if an error value exceeds a threshold value, then iteratively performing the steps of;

modifying a display image luminance based on an input luminance and a brightness parameter, a sharpness parameter, and a contrast parameter;

transforming a display image luminance based on a human luminance perception model and generating a display visual response image;

comparing the display visual response image with a reference visual response image to generate the error value; and

modifying at least one of a set of tone-mapping parameters comprising;

the brightness parameter, the sharpness parameter, and the contrast parameter.

2. The method of image rendering of claim 1 further comprising, after the step of modifying a display image luminance based on an input luminance and a brightness parameter, a sharpness parameter, and a contrast parameter, the step of modifying a display image chrominance based on a white light bias parameter, and, wherein the set of tone-mapping parameters further comprises the white light bias parameter.

3. The method of image rendering of claim 1 further comprising, after the step of modifying a display visual image luminance based on an input luminance and a brightness parameter, a sharpness parameter, and a contrast parameter, the step of:

if, on a pixel-by-pixel basis, a display image color radiance component exceeds a display-limited range, then limiting, on a pixel-by-pixel basis, the display image color radiance component to the exceeded display-limited range value.

4. The method of image rendering of claim 1 further comprising, after the step of modifying a display image luminance based on the human luminance perception model, the step of shaping a spatial frequency transform of the modified display image with a contrast sensitivity function and thereafter generating the display visual response image.

5. The method of image rendering of claim 1 further comprising, preceding the step of testing whether the error value exceeds the threshold value, the steps of modifying the reference image luminance based on a human luminance perception model and shaping a spatial frequency transform of the modified display image with a contrast sensitivity function and thereafter generating the reference visual response image.

6. The method of image rendering of claim 5 wherein the contrast sensitivity function is a function of viewing distance.

7. The method of claim 1 wherein the human luminance perception model comprises a just-noticeable-difference (JND) encoding function.

8. The method of claim 1 wherein the error value is a mean square error value.

9. The method of claim 1 wherein a second error value is generated for comparing with the threshold value via a determination of the maximal pixel difference between the display response image and the reference response image.

10. A method of image rendering comprising:

modifying a reference visual image luminance based on a human luminance perception model;

shaping a spatial frequency transform of the modified reference image with a contrast sensitivity function and generating a reference visual response image;

if an error value exceeds a threshold value, then iteratively performing the steps of;

modifying a display image luminance based on an input luminance and a brightness parameter, a sharpness parameter, and a contrast parameter;

if, on a pixel-by-pixel basis, a display image color radiance component exceeds a display-limited range, then limiting, on a pixel-by-pixel basis, the display image color radiance component to the exceeded display-limited range value;

transforming a display image luminance based on the human luminance perception model;

shaping a spatial frequency transform of the modified display image with the contrast sensitivity function and generating a display visual response image;

comparing the display visual response image with the reference visual response image to generate an error value; and

modifying at least one of a set of tone-mapping parameters comprising;

the brightness parameter, the sharpness parameter, and the contrast parameter.

11. The method of image rendering of claim 10 further comprising modifying a display image chrominance based on a white light bias parameter prior to limiting, on a pixel-by-pixel basis, the display image color radiance component to the exceeded display-limited range value and, wherein the set of tone-mapping parameters further comprises the white light bias parameter.

12. The method of image rendering of claim 10 wherein the contrast sensitivity function is a function of viewing distance.

13. The method of claim 10 wherein the human luminance perception model comprises a just-noticeable-difference (JND) encoding function.

14. The method of claim 10 wherein the error value is a mean square error value.

15. The method of claim 10 wherein the error value is generated via a determination of the maximal pixel difference between the display visual response image and the reference visual response image.

16. A system for image rendering comprising:

a first display image luminance processing module having a processing unit, and addressable memory, the first display image luminance processing module adapted to modify a display image luminance based on an input luminance and a brightness parameter, a sharpness parameter, and a contrast parameter;

a second display image luminance module, executable via a processing unit having addressable memory, wherein the second display image luminance module is adapted to modify a display image luminance based on a human luminance perception model;

a shaping module, executable via a processing unit having addressable memory, wherein the filtering module is adapted to shape the spatial frequency response of the modified display image with a contrast sensitivity function and adapted to generate a display visual response image;

a comparator module, executable via a processing unit having addressable memory, wherein the comparator module is adapted to generate an error value based on the generated display visual response image and a reference visual response image; and

a parameter processing module, executable via a processing unit having addressable memory, wherein the parameter processing module is adapted to modify at least one of a set of tone-mapping parameters comprising;

the brightness parameter, the sharpness parameter, and the contrast parameter;

wherein the parameter modification is based on the generated error value.

17. The system of claim 16 further comprising a display processing module, executable via a processing unit having addressable memory, wherein the display processing module is adapted to modify a display image chrominance based on a white light bias parameter;

and, wherein the set of tone-mapping parameters further comprises the white light bias parameter.

18. The system of claim 17 wherein the display processing module is further adapted to limit, on a pixel-by-pixel basis, when a display image color radiance component exceeds a display-limited range, then limiting, on a pixel-by-pixel basis, the display image color radiance component to the exceeded display-limited range value.

19. The system of claim 16 further comprising a reference image processing module, executable via a processing unit having addressable memory, wherein the reference image processing module is adapted to modify a reference image luminance based on a human luminance perception model and shaping the spatial frequency transform of the modified reference image with a contrast sensitivity function and generate a reference response image.

20. The system of claim 16 wherein the first display image luminance processing module is further adapted to modify a reference image luminance based on a human luminance perception model and shaping the spatial frequency transform of the modified reference image with a contrast sensitivity function and generate a reference response image.

21. An apparatus for image rendering comprising:

a processing module having a processing unit, and addressable memory wherein the processing module is adapted to execute the following steps while an error value is above a threshold value;

modify a display image luminance based on an input luminance and a brightness parameter, a sharpness parameter, and a contrast parameter;

modify a display image luminance based on a human luminance perception model;

shape the modified display image spatial frequency transform with a contrast sensitivity function and generate a display visual response image;

compare the generated display visual response image with a reference visual response image to generate the error value; and

modify at least one of a set of tone-mapping parameters comprising;

the brightness parameter, the sharpness parameter, the contrast parameter.

22. The apparatus for image rendering of claim 21 wherein the processing module is further adapted to modify a display image chrominance based on a white light bias parameter, and limit, on a pixel-by-pixel basis, when a display image color radiance component exceeds a display-limited range, then limiting, on a pixel-by-pixel basis, the display image color radiance component to the exceeded display-limited range value and, wherein the set of tone-mapping parameters further comprises the white light bias parameter.

23. The apparatus for image rendering of claim 22 wherein the processing module is further adapted to modify a reference image luminance based on a human luminance perception model and shape a spatial frequency transform of the modified reference image with a contrast sensitivity function and thereafter generate the reference visual response image.