Method and apparatus for sharpening digital images

1. A method for sharpening a digital image captured by a digital imaging device, the method comprising:

for each pixel X m,n of the digital image:

at an edge detector determining an edge parameter E, the edge parameter E providing an indication of whether the pixel X m,n is at an edge of the digital image;

at a noise detector determining a noise parameter σ, the noise parameter σ providing an indication of whether the pixel X m,n is a noise in the digital image;

at a scaling module determining a scaling factor α m,n based on a combination of the edge parameter E and the noise parameter σ; and

at an image sharpening module applying the scaling factor α m,n on a pixel by pixel basis to sharpen the digital image to get a sharpened pixel Y m,n .

2. The method of claim 1 , wherein determining the edge parameter E comprises determining whether the pixel X m,n is on a dark side of the edge or on a light side of the edge.

3. The method of claim 2 , further comprising at an image darkening module determining an offset parameter U m,n when the pixel X m,n is determined to be on the dark side of the edge.

4. The method of claim 3 , wherein the image darkening module darkens in order to sharpen the pixel X m,n using the offset parameter U m,n .

5. The method of claim 3 , further comprises at an adder generating an output image pixel T m,n based on a combination of the sharpened pixel Y m,n and the offset parameter U m,n .

6. The method of claim 1 , wherein the image sharpening module is an unsharp masking module.

7. The method of claim 6 , further comprising discarding the scaling factor α m,n when a value of the pixel X m,n is outside a range defined by the neighborhood pixels.

8. The method of claim 1 , wherein determining the noise parameter σ comprises comparing the pixel X m,n with neighborhood pixels centered on the pixel X m,n .

9. An image processor for sharpening a digital image captured by a image processing system, the image processor comprising:

for each pixel X m,n of the digital image:

an edge detector capable of determining an edge parameter E, the edge parameter E provides an indication of whether the pixel X m,n is at an edge of the digital image;

a noise detector capable of determining a noise parameter σ, the noise parameter σ provides an indication of whether the pixel X m,n is a noise in the digital image;

a scaling module coupled to the edge detector and to the noise detector, the scaling module capable of determining a scaling factor α m,n based on a combination of the edge parameter E and the noise parameter σ; and

an image sharpening module coupled to the scaling module, the image sharpening module capable of utilizing the scaling factor α m,n on a pixel by pixel basis to sharpen the digital image to get a sharpened pixel Y m,n .

10. The image processor of claim 9 , wherein the edge detector further determines whether the pixel X m,n is on a dark side of the edge or on a light side of the edge.

11. The image processor of claim 10 , further comprising an image darkening module determining an offset parameter U m,n when the pixel X m,n is determined to be on the dark side of the edge.

12. The image processor of claim 11 , further comprises an adder capable of generating an output image pixel T m,n based on a combination of the sharpened pixel Y m,n and the offset parameter U m,n .

13. The image processor of claim 10 , wherein the image darkening module darkens in order to sharpen the pixel X m,n using the offset parameter U m,n .

14. The image processor of claim 9 , wherein the image sharpening module is an unsharp masking module.

15. The image processor of claim 9 , wherein determining the noise parameter σ comprises comparing the pixel X m,n with neighborhood pixels centered on the pixel X m,n .

16. A non-transitory computer readable medium containing a computer program product for sharpening a digital image captured by a digital imaging device, the computer program product comprising:

for each pixel X m,n of the digital image:

program code for determining an edge parameter E, the edge parameter E providing an indication of whether the pixel X m,n is at an edge of the digital image;

program code for determining a noise parameter σ, the noise parameter σ providing an indication of whether the pixel X m,n is a noise in the digital image;

program code for determining a scaling factor α m,n based on a combination of the edge parameter E and the noise parameter σ; and

program code for applying the scaling factor α m,n on a pixel by pixel basis to sharpen the digital image to get a sharpened pixel Y m,n .

17. The computer program product of claim 16 , wherein determining the edge parameter E comprises determining whether the pixel X m,n is on a dark side of the edge or on a light side of the edge.

18. The computer program product of claim 17 , further comprising program code for determining an offset parameter U m,n when the pixel X m,n is determined to be on the dark side of the edge.

19. The computer program product of claim 18 , wherein the program code darkens in order to sharpen the pixel X m,n using the offset parameter U m,n .

20. The computer program product of claim 18 , further comprises program code for generating an output image pixel T m,n based on a combination of the sharpened pixel Y m,n and the offset parameter U m,n .