Distortion correction of images using hybrid interpolation technique

1. A method, comprising:

using a first array of pixels for an image to calculate corrected coordinates of a second array of pixels for a corrected image wherein the corrected coordinates correct a geometrical distortion of the image caused by a non-optimal lens system in a camera; and

interpolating, by a digital image processor, color components of the first array of pixels using said corrected coordinates and a hybrid interpolation technique, wherein at least one color component of the first array of pixels is interpolated using a quality interpolator which is different from quality interpolators used for other color components of the first array of pixels, wherein the aspect ratio of the image is maintained in the corrected image.

2. The method of claim 1 , wherein out of said color components, said at least one color component is a luminance color component and two other color components are chrominance color components, wherein the quality interpolator for the luminance color component is of higher quality than the quality interpolators for the chrominance color components.

3. The method of claim 2 , wherein the quality interpolator of said luminance color component is a bicubic interpolator, and the quality interpolator for the two chrominance color components is a bilinear interpolator.

4. The method of claim 1 , wherein all said color components have different quality interpolators.

5. The method of claim 1 , wherein said geometrical distortion caused by a non-optimal lens system in a camera is a radial distortion.

6. The method of claim 1 , wherein said calculating of the corrected coordinates comprises:

creating a look-up table for a correction function for a finite number of discrete values of at least one parameter, said correction function being a function of said at least one parameter;

calculating said at least one parameter for each pixel of said image for the original pixel coordinates;

choosing a value of said correction function calculated for one of the discrete values of the at least one parameter from said look-up table by matching said at least one calculated parameter with said one of the discrete values of the at least one parameter for each pixel using said look-up table; and

computing said corrected coordinates of the pixels by using said chosen value of the correction function for said each pixel of said image.

7. The method of claim 6 , wherein said correction function comprises a digital zoom factor so that digital zoom is jointly performed with said correcting said geometrical distortion caused b a non-optimal lens system in a camera.

8. The method of claim 6 , wherein said at least one parameter is a squared radius, said radius being a distance between a location of a pixel and a center point of the distortion.

9. The method of claim 8 , wherein said calculating said squared radius is performed using at least one of:

a double axial symmetry; and

a single axial symmetry.

10. The method of claim 8 , wherein said calculating said squared radius is performed using a first previously calculated squared radius for a first preceding pixel and using a second previously calculated squared radius for a second preceding pixel.

11. The method of claim 1 , wherein a digital zoom and said correcting said geometrical distortion caused by a non-optimal lens system in a camera are performed jointly.

12. A non transitory computer program product comprising: a computer readable storage structure embodying computer program code thereon configured to be executed by a computer processor, wherein said computer program code comprises instructions for performing the method of claim 1 , indicated as being performed by any component or a combination of components of a digital image processor or of an electronic device comprising said digital image processor.

13. A digital image processor, comprising:

a corrected coordinate calculation block, configured to use a first array of pixels for an image to calculate corrected coordinates of a second array of pixels for a corrected image wherein the corrected coordinates correct a geometrical distortion of the image caused by a non-optimal lens system in a camera; and

a hybrid interpolation block, confiqured to interpolate color components of the first array of pixels using said corrected coordinates and a hybrid interpolation technique, wherein the hybrid interpolation block is configured to interpolate at least one color component of the first array of pixels using a quality interpolator which is different from quality interpolators used for other color components of the first array of pixels, wherein the aspect ratio of the image is maintained in the corrected image.

14. The digital image processor of claim 13 , wherein out of said color components, said at least one color component is a luminance color component and two other color components are chrominance color components, wherein the quality interpolator for the luminance color component is of higher quality than the quality interpolators for the chrominance color components.

15. The digital image processor of claim 14 , wherein the quality interpolator of said luminance color component is a bicubic interpolator, and the quality interpolator for the two chrominance color components is a bilinear interpolator.

16. The digital image processor of claim 13 , wherein all said color components have different quality interpolators.

17. The digital image processor of claim 13 , wherein said geometrical distortion caused by a non-optimal lens system in a camera is a radial distortion.

18. The digital image processor of claim 13 , wherein said corrected coordinate calculation block comprises:

a look up table calculator block, for creating a look-up table for a correction function for a finite number of discrete values of at least one parameter, said correction function being a function of said at least one parameter;

a parameter calculation means, for calculating said at least one parameter for each pixel of said image for the original pixel coordinates;

a look-up table, for storing values of said correction function for the finite number of values of said at least one parameter, and for choosing a value of said correction function calculated for one of the discrete values of the at least one parameter by matching said at least one calculated parameter with said one of the discrete values of the at least one parameter for each pixel using said look-up table; and

a corrected coordinate computation means, for computing said corrected coordinates of the pixels by using said chosen value of the correction function for said each pixel of said image.

19. The digital image processor of claim 18 , wherein said correction function comprises a digital zoom factor so that digital zoom is jointly performed with said correcting said geometrical distortion caused by a non-optimal lens system in a camera.

20. The digital image processor of claim 18 , wherein said at least one parameter is a squared radius, said radius being a distance between a location of a pixel and a center point of the distortion.

21. The digital image processor of claim 20 , wherein said calculating said squared radius is performed using at least one of:

a double axial symmetry; and

a single axial symmetry.

22. The digital image processor of claim 20 , wherein said calculating said squared radius is performed using a first previously squared radius for a first preceding pixel and using a second previously calculated squared radius for a second preceding pixel.

23. The digital image processor of claim 13 , wherein a digital zoom and said correcting said geometrical distortion caused by a non-optimal lens system in a camera are performed jointly.

24. An electronic device, comprising:

a camera, configured to generate an image;

a digital image processor, comprising:

a corrected coordinate calculation block, configured to use a first array of pixels for an image to calculate corrected coordinates of a second array of pixels for a corrected image wherein the corrected coordinates correct a geometrical distortion of the image caused by a non-optimal lens system in the camera; and

a hybrid interpolation block, configured to interpolate color components of the first array of pixels using said corrected coordinates and a hybrid interpolation technique, wherein the hybrid interpolation block is configured to interpolate at least one color component of the first array of pixels using a quality interpolator which is different from quality interpolators used for other color components of the first array of pixels, wherein the aspect ratio of the image is maintained in the corrected image.

25. The digital image processor of claim 13 , wherein said digital image processor is a part of a digital camera, a communication device, a wireless communication device, a portable electronic device, a mobile electronic device or a camera phone.

26. The electronic device of claim 24 , wherein out of said color components, said at least one color component is a luminance color component and two other color components are chrominance color components, wherein the quality interpolator for the luminance color component is of higher quality than the quality interpolators for the chrominance color components.

27. The electronic device of claim 26 , wherein the quality interpolator of said luminance color component is a bicubic interpolator, and the quality interpolator for the two chrominance color components is a bilinear interpolator.

28. The electronic device of claim 24 , wherein all said color components have different quality interpolators.

29. The electronic device of claim 24 , wherein said geometrical distortion caused by a non-optimal lens system in the camera is a radial distortion.

30. The electronic device of claim 24 , wherein said corrected coordinate calculation block comprises:

a look up table calculator block, for creating a look-up table for a correction function for a finite number of discrete values of at least one parameter, said correction function being a function of said at least one parameter;

a parameter calculation means, for calculating said at least one parameter for each pixel of said image for the original pixel coordinates;

a look-up table, for storing values of said correction function for the finite number of values of said at least one parameter, and for choosing a value of said correction function calculated for one of the discrete values of the at least one parameter by matching said at least one calculated parameter with said one of the discrete values of the at least one parameter for each pixel using said look-up table; and

a corrected coordinate computation means, for computing said corrected coordinates of the pixels by using said chosen value of the correction function for said each pixel of said image.

31. The electronic device of claim 30 , wherein said at least one parameter is a squared radius, said radius being a distance between a location of a pixel and a center point of the distortion.

32. The electronic device of claim 31 , wherein said calculating said squared radius is performed using at least one of:

a double axial symmetry; and

a single axial symmetry.

33. The electronic device of claim 31 , wherein said calculating said squared radius is performed using a first previously calculated squared radius for a first preceding pixel and using a second previously calculated squared radius for a second preceding pixel.

34. The electronic device of claim 30 , wherein said correction function comprises a digital zoom factor so that digital zoom is jointly performed with said correcting said geometrical distortion caused by a non-optimal lens system in the camera.

35. The electronic device of claim 24 , wherein a digital zoom and said correcting said geometrical distortion caused by a non-optimal lens system in the camera are performed jointly.

36. An electronic device, comprising:

means for generating an image;

processing means, comprising:

means for using a first array of pixels for an image to calculate corrected coordinates of a second array of pixels for a corrected image wherein the corrected coordinates correct a geometrical distortion of the image caused by a non-optimal lens system in a camera; and

means for interpolating color components of the first array of pixels using said corrected coordinates and a hybrid interpolation technique, wherein at least one color component of the first array of pixels is interpolated using a quality interpolator which is different from quality interpolators used for other color components of the first array of pixels, wherein the aspect ratio of the image is maintained in the corrected image.

37. The electronic device of claim 36 , wherein said means for generating an image is a camera, said processing means is a digital image processor, said means for calculating is a corrected coordinate calculation block, and said means for interpolating is a hybrid interpolation block.

38. A method comprising:

digitally correcting for a geometric distortion in an image by changing the position of pixels; and

performing, by a digital image processor, a hybrid interpolation to produce a final image wherein for pixels of the final image a first colour component is interpolated using a first interpolator and a second colour component is interpolated using a second interpolator, wherein the first and second colour components are different and the first and second interpolators are of different quality and the first interpolator is of higher duality than the second interpolator.

39. The method of claim 38 wherein the aspect ratio of the image is maintained when correcting for a geometric distortion.