Method and system for three-dimensional noise reduction and contrast enhancement of images

1. A method for a camera, comprising:

receiving, by a processor, a current frame;

calculating, by the processor, a spatial weight for each pixel s in the current frame, wherein the spatial weight is computed based on a summation of diffused values associated with the pixel s;

selectively filtering, by the processor, an intensity I of the pixel s spatially using the spatial weight; and

controlling, by the processor, a display device to display the current frame based on the selective filtering.

2. The method of claim 1 , wherein the diffused values comprise intensity differences between the pixel s and its neighbours in a spatial domain.

3. The method of claim 1 , wherein the method further comprises

selectively filtering, by the processor, the intensity I of the pixel s based on the summation of diffused values is less than a threshold value.

4. The method of claim 3 , wherein the diffused values are calculated according to the formula:

T _weight_spatial=Σψ( I ( t,p )− I ( t,s )); where I

represents pixel intensity; and

(t,s) specifies each pixel s in the current frame.

5. The method of claim 4 , wherein filtering the intensity I of the pixel s spatially is according to the formula:

Spatial_filtered_sample= I ( t,s )+λ* T _weight_spatial; where λ is a constant.

6. The method of claim 5 , wherein selectively filtering the intensity I of the pixel s spatially comprises selecting a constant value rho such that:

ψ( x )=(1−( x/rho ){circumflex over ( )}2){circumflex over ( )}2; if | x|<=rho;

ψ( x )=0; if | x|>rho.

7. The method of claim 6 , wherein rho is selected to be proportional to a variance of noise in the current frame image.

8. The method of claim 1 , wherein the method further comprises

temporally filtering, by the processor, the spatially filtered intensity I of the pixel s based on a temporal weight calculated between the intensity I of the pixel s in the current frame and its value from an immediately preceding frame.

9. The method of claim 8 , wherein the temporal weight is calculated according to the formula:

T _weight_temporal=ψ( I ( t− 1, s )− I ( t,s ));

where I(t,s) is the intensity of the pixel s in current frame; and

I(t−1, s) is its intensity from the immediately preceding frame (t−1).

10. The method of claim 9 , further comprising

outputting, by the processor, a temporally filtered pixel calculated in accordance with the following formula:

Temporal_filtered_sample−spatial_filtered_sample+λ* T _weight_temporal;

where λ is a constant.

11. The method of claim 10 , further comprising

enhancing, by the processor, contrast in the current frame by applying a contrast enhancement function H(s) to each pixel s with value altered due to the spatial filtering.

12. The method of claim 11 , wherein applying the contrast enhancement comprises following formula:

T _weight( s )=Σψ( I ( t,p )− I ( t,s ));

I (+1, s )= I ( t,s )+λ* T _weight( s ); if | T _weight( s )|>0;

I ( t+ 1, s )= I ( t,s )+λ* H ( s ); if | T _weight( s )|equals0; and

wherein k is a constant.

13. The method of claim 11 , wherein the contrast enhancement function H(s) comprises an edge detection algorithm.

14. The method of claim 13 , wherein the edge detection algorithm is based on at least one of a Sobel operator or a Laplacian operator.

15. The method of claim 11 , wherein the contrast enhancement function H(s) is calculated in accordance with the following formula:

H ( s )=Laplacian( s )*Sobel( s );

wherein Laplacian(s) is a Laplacian operator, and Sobel(s) is a Sobel operator.

16. An image processing system, comprising:

a processor configured to:

receive a current frame;

calculate, in a spatial filtering block of an image processing pipeline, a spatial weight for each pixel s in the current frame, wherein the spatial weight is computed based on a summation of diffused values associated with the pixel s;

selectively filter, as a step within the image processing pipeline, an intensity I of the pixel s spatially using the spatial weight; and

control a display device to display the current frame based on the selective filtering.

17. The image processing system according to claim 16 , wherein the diffused values comprise intensity differences between the pixel s and its neighbours in a spatial domain.

18. The image processing system according to claim 16 , wherein the processor is further configured to selectively filter the intensity I of the pixel s based on the summation of diffused values is less than a threshold value.

19. The image processing system according to claim 16 , wherein the processor is further configured to temporally filter the spatially filtered intensity I of the pixel s based on a temporal weight calculated between the intensity I of the pixel s in the current frame and its value from an immediately preceding frame.

20. The image processing system according to claim 19 , wherein the temporal weight is calculated according to the formula:

T _weight_temporal=ψ( I ( t− 1, s )− I ( t,s ));

where I(t,s) is the intensity of the pixel s in current frame; and

I(t−1, s) is its intensity from the immediately preceding frame (t−1).