SYSTEM, METHOD, AND COMPUTER PROGRAM PRODUCT FOR IMPLEMENTING A SPATIALLY VARYING UNSHARP MASK NOISE REDUCTION FILTER

• US 20140185952A1
• Filed: 12/28/2012
• Published: 07/03/2014
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Cabral, Brian K.
• Granted Patent: US 9,082,180 B2
• Time in Patent Office: Days
• US Class Current: 382/263
• CPC Class Codes: G06T 2200/28 involving image processing hardware
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 5/004 Unsharp masking
• CPC Class Codes: G06T 5/75 Unsharp masking

Abstract

A system, method, and computer program product for applying a spatially varying unsharp mask noise reduction filter is disclosed. The spatially varying unsharp mask noise reduction filter generates a low-pass filtered image by applying a low-pass filter to a digital image, generates a high-pass filtered image of the digital image, and generates an unsharp masked image based on the low-pass filtered image and the high-pass filtered image. The filter also blends the low-pass filtered image with the unsharp masked image based on a shaping function.

Claims

1. A method comprising:

generating a low-pass filtered image by applying a low-pass filter to a digital image;

generating a high-pass filtered image of the digital image;

generating an unsharp masked image based on the low-pass filtered image and the high-pass filtered image; and

blending the low-pass filtered image with the unsharp masked image based on a shaping function.

2. The method of claim 1, wherein generating the high-pass filtered image comprises calculating the difference between the digital image and the low-pass filtered image.

3. The method of claim 1, wherein generating the unsharp masked image comprises combining the low-pass filtered image and a scaled version of the high-pass filtered image.

4. The method of claim 3, wherein generating the unsharp masked image comprises scaling the high-pass filtered image based on a coring function.

5. The method of claim 1, wherein blending the low-pass filtered image with the unsharp masked image comprises performing a linear interpolation between the low-pass filtered image and the unsharp masked image based on the shaping function.

6. The method of claim 5, wherein an input to the shaping function comprises a function of a pixel value of the high-pass filtered image.

7. The method of claim 6, wherein the input to the shaping function is based on a noise amplitude cutoff parameter.

8. The method of claim 1, wherein the low-pass filtered image is generated by applying a convolution kernel to each pixel of the digital image.

9. The method of claim 8, wherein the convolution kernel is implemented in software configured to be executed on a graphics processing unit.

10. The method of claim 1, wherein a value returned by the shaping function is generated using a look-up table (LUT).

11. The method of claim 10, wherein an index into the LUT comprises a function of a pixel value of the high-pass filtered image.

12. The method of claim 10, wherein the LUT table represents a Gaussian function.

13. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, cause the processor to perform steps comprising:

generating a low-pass filtered image by applying a low-pass filter to a digital image;

generating a high-pass filtered image of the digital image;

generating an unsharp masked image based on the low-pass filtered image and the high-pass filtered image; and

blending the low-pass filtered image with he unsharp masked image based on a shaping function.

14. The non-transitory computer-readable storage medium of claim 13, wherein blending the low-pass filtered image with the unsharp masked image comprises performing a linear interpolation between the low-pass filtered image and the unsharp masked image based on the shaping function.

15. The non-transitory computer-readable storage medium of claim 14, wherein an input to the shaping function comprises a function of a pixel value of the high-pass filtered image.

16. The non-transitory computer-readable storage medium of claim 13, wherein a value returned by the shaping function is generated using a look-up table (LUT).

17. A system, comprising:

a memory storing a digital image; and

a processing unit configured to;

generate a low-pass filtered image by applying a low-pass filter to a digital image,

generate a high-pass filtered image of the digital image,

generate an unsharp masked image based on the low-pass filtered image and the high-pass filtered image, and

blend the low-pass filtered image with the unsharp masked image based on a shaping function.

18. The system of claim 17, wherein blending the low-pass filtered image with the unsharp masked image comprises performing a linear interpolation between the low-pass filtered image and the unsharp masked image based on the shaping function.

19. The system of claim 17, wherein the processing unit is a graphics processing unit.

20. The system of claim 19, wherein the processing unit is included in a system-on-chip (SoC) that further comprises a central processing unit.