Noise reduction method utilizing statistical weighting, apparatus, and program for digital image processing

• US 6,718,068 B1
• Filed: 03/10/2000
• Issued: 04/06/2004
• Est. Priority Date: 03/10/2000
• Status: Expired due to Term

• Current Assignee: Monument Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Eastman Kodak Company
• Inventors: Luo, Jiebo, Gindele, Edward B.
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Dang, Duy M.
• Application Number:
  US09/522,742
• Time in Patent Office: 1,488 Days
• Field of Search: 382/266, 382/254, 382/260-264, 382/272, 382/172
• US Class Current: 382/254
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing

Abstract

A method of processing a digital image channel to remove noise, includes the steps of: identifying a pixel of interest; identifying at least two sampled local regions of pixels which include the pixel of interest; calculating a noise free pixel estimate for each sampled local region of pixels; calculating a statistical weighting factor for each sampled local region, the calculation of the statistical weighting factor being independent of the calculation of the noise free pixel estimate; and using the noise free pixel estimates and the statistical weighting factors for calculate a noise reduced pixel value.

Claims

1. A method of processing a digital image channel to remove noise, comprising the steps of:

a) identifying a pixel of interest;

b) identifying at least two sampled local regions of pixels which include the pixel of interest;

c) calculating a noise free pixel estimate for each sampled local region of pixels;

d) calculating a statistical weighting factor for each sampled local region, the calculation of the statistical weighting factor being independent of the calculation of the noise free pixel estimate; and

e) using the noise free pixel estimates and the statistical weighting factors to calculate a noise reduced pixel value.

2. The method claimed in claim 1, wherein steps a) through e) are repeated for all pixels in the image.

3. The method claimed in claim 1, wherein the image includes a plurality of channels and wherein steps a) through e) are repeated for all pixels in all of the channels of the digital image.

4. The method claimed in claim 1, wherein the sampled local regions define radial patterns of pixels emanating from the pixel of interest.

5. The method claimed in claim 1, wherein the statistical weighting factor is a function of a standard deviation of the pixel values in the sampled local regions.

6. The method claimed in claim 5, wherein the function is a power function.

7. The method claimed in claim 1, wherein the statistical weighting factor is a function of a mean absolute deviation of the pixel values in the sampled local regions.

8. The method claimed in claim 7, wherein the function is a power function.

9. The method claimed in claim 1, wherein the statistical weighting factor is a function of the maximum deviation of the pixel values in the sampled local regions.

10. The method claimed in claim 9, wherein the function is a power function.

11. A computer program product for performing the method of claim 1.

12. Apparatus for processing a digital image channel to remove noise, comprising:

a) means for identifying a pixel of interest;

b) means for identifying at least two sampled local regions of pixels which include the pixel of interest;

c) means for calculating a noise free pixel estimate for each sampled local region of pixels;

d) means for calculating a statistical weighting factor for each sampled local region, the calculation of the statistical weighting factor being independent of the calculation of the noise free pixel estimate; and

e) means for using the noise free pixel estimates and the statistical weighting factors to calculate a noise reduced pixel value.

13. The apparatus claimed in claim 12, further comprising means for calculating a noise reduced pixel value for all pixels in the image.

14. The apparatus claimed in claim 12, wherein the image includes a plurality of channels and wherein the apparatus further includes means for calculating a noise reduce pixel value for all pixels in all of the channels of the digital image.

15. The apparatus claimed in claim 12, wherein the sampled local regions define radial patterns of pixels emanating from the pixel of interest.

16. The apparatus claimed in claim 12, wherein the statistical weighting factor is a function of a standard deviation of the pixel values in the sampled local regions.

17. The apparatus claimed in claim 16, wherein the function is a power function.

18. The apparatus claimed in claim 12, wherein the statistical weighting factor is a function of a mean absolute deviation of the pixel values in the sampled local regions.

19. The apparatus claimed in claim 18, wherein the function is a power function.

20. The apparatus claimed in claim 12, wherein the statistical weighting factor is a function of the maximum deviation of the pixel values in the sampled local regions.

21. The apparatus claimed in claim 20, wherein the function is a power function.