Method for real-time implementable local tone mapping for high dynamic range images

• US 20090041376A1
• Filed: 08/04/2008
• Published: 02/12/2009
• Est. Priority Date: 08/03/2007
• Status: Active Grant

• Current Assignee: University of Akron
• Original Assignee: University of Akron
• Inventors: Carletta, Joan Elizabeth, Hassan, Firas Hussein
• Granted Patent: US 9,830,691 B2
• Time in Patent Office: Days
• US Class Current: 382/274
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 5/009 Global, i.e. based on properties of the image as a whole applied in cameras using an electronic image sensor H04N23/80, H04N23/70
• 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

Abstract

The present invention relates to a method capable of real-time implementable local tone mapping of high dynamic range images. In one embodiment, the present invention relates to a method capable of accomplishing real-time local tone mapping of high dynamic range images so that they have clear details without, for example, halo artifacts when viewed on standard display devices. In another embodiment, the present invention relates to a method capable of accomplishing real-time local tone mapping of high dynamic range images so that they have clear details without, for example, halo artifacts when viewed on standard display devices where such a method utilizes, in part, a modified Reinhard operator.

Claims

1. A method for achieving the local tone mapping of high dynamic range images comprising the steps of:

(A) providing at least one HDR RGB triplet suitable for local tone mapping;

(B) calculating at least one luminance component of the at least one HDR RGB triplet using a luminance computation sub-block;

(C) supplying the one or more luminance components to at least one approximated Gaussian pyramid sub-block and at least one log average sub-block, wherein the luminance components supplied to the at least one approximated Gaussian pyramid sub-block and at least one log average sub-block are used to, respectively, generate at least one local illumination estimate and at least one global illumination estimate;

(D) buffering the HDR RGB triplet in at least one buffer sub-block; and

(E) supplying the at least one local illumination estimate, the at least one global illumination estimate, the at least one luminance component and the buffered RGB triplet to a color tone mapping sub-block to generate a mapped RGB triplet.

2. The method of claim 1, wherein the method is carried out in an embedded system selected from general purpose digital signal processors, field programmable gate arrays (FPGAs), or application specific integrated circuits.

3. The method of claim 2, wherein the method is carried out in a field programmable gate arrays (FPGAs).

4. The method of claim 1, wherein the method is carried out in the processing portion of a digital camera.

5. The method of claim 1, wherein steps (B), (C) and (D) are carried out simultaneously.

6. The method of claim 5, wherein the method is carried out in an embedded system selected from general purpose digital signal processors, field programmable gate arrays (FPGAs), or application specific integrated circuits.

7. The method of claim 6, wherein the method is carried out in a field programmable gate arrays (FPGAs).

8. The method of claim 5, wherein the method is carried out in the processing portion of a digital camera.

13. The method of claim 1, wherein steps (b) and (c) are carried out simultaneously.

14. The method of claim 13, wherein the method is carried out in an embedded system selected from general purpose digital signal processors, field programmable gate arrays (FPGAs), or application specific integrated circuits.

15. The method of claim 14, wherein the method is carried out in a field programmable gate arrays (FPGAs).

16. The method of claim 13, wherein the method is carried out in the processing portion of a digital camera.

9. A method for achieving the local tone mapping of high dynamic range images comprising the steps of:

(a) providing at least one input pixel stream suitable for local tone mapping;

(b) calculating at least one local luminance estimate of the at least one input pixel stream using a approximated Gaussian pyramid sub-block;

(c) calculating at least one global illumination estimate of the at least one input pixel stream using a log average sub-block, and

(d) normalizing the at least one input pixel stream by subjecting it to a weighted sum of the at least one local illumination estimate and the at least one global illumination estimate in order to generate a mapped output pixel stream.

10. The method of claim 9, wherein the method is carried out in an embedded system selected from general purpose digital signal processors, field programmable gate arrays (FPGAs), or application specific integrated circuits.

11. The method of claim 10, wherein the method is carried out in a field programmable gate arrays (FPGAs).

12. The method of claim 9, wherein the method is carried out in the processing portion of a digital camera.