CORRECTION OF CLUSTER DEFECTS IN IMAGERS

• US 20110221939A1
• Filed: 05/20/2011
• Published: 09/15/2011
• Est. Priority Date: 08/03/2005
• Status: Active Grant

• Current Assignee: Dmitri Jerdev
• Original Assignee: Dmitri Jerdev
• Inventors: Jerdev, Dmitri
• Granted Patent: US 8,817,135 B2
• Time in Patent Office: Days
• US Class Current: 348/246
• CPC Class Codes: H04N 2209/046 Colour interpolation to calculate the missing colour values
• CPC Class Codes: H04N 25/68 applied to defects

Abstract

A method and apparatus that allows for the correction of multiple defective pixels in an imager device. In one exemplary embodiment, the method includes the steps of selecting a correction kernel for a defective pixel, determining average and difference values for pixel pairs in the correction kernel, and substituting an average value from a pixel pair for the value of the defective pixel.

Claims

1-21. -21. (canceled)

22. A method of correcting a defective pixel in an imaging circuit, said imaging circuit having an array comprising a plurality of pixels, said method comprising:

identifying a pixel for correction;

selecting a first pair of pixels including a first pixel and a second pixel and a second pair of pixels including a third pixel and a fourth pixel; and

if said first, second, third, and fourth pixels are not defective;

determining an average pixel value and a difference pixel value for said first pair of pixels and said second pair of pixels; and

substituting said average pixel value of one of said first pair of pixels and said second pair of pixels for a pixel value of said pixel for correction.

23. The method of claim 22, said step of selecting a first pair of pixels and a second pair of pixels further comprising:

determining if a first two pairs of pixels include any defective pixels; and

if said first two pairs of pixels do not include any defective pixels, selecting said first two pairs of pixels as said first pair of pixels and said second pair of pixels.

24. The method of claim 23, said step of selecting a first pair of pixels further comprising:

if said first two pairs of pixels do include at least one defective pixel, selecting a second two pairs of pixels as said first pair of pixels and said second pair of pixels.

25. The method of claim 24, wherein said first two pairs of pixels are a nearest two pairs of pixels to said pixel for correction in said array that correspond to a same color as said pixel for correction.

26. The method of claim 25, wherein said second two pairs of pixels are a next-nearest two pairs of pixels to said pixel for correction in said array that correspond to said same color as said pixel for correction.

27. The method of claim 22, wherein said first pixel and said second pixel are located symmetrically surrounding said pixel for correction in said array, and said third pixel and said fourth pixel are located symmetrically surrounding said pixel for correction in said array.

28. The method of claim 22, further comprising:

if at least one of said first, second, third, and fourth pixels are defective, substituting a pixel value of a non-defective pixel for said pixel value of said pixel for correction.

29. The method of claim 28, wherein said non-defective pixel is a nearest non-defective pixel to said pixel for correction in said array that corresponds to a same color as said pixel for correction.

30. The method of claim 22, wherein said step of substituting said average pixel value for a pixel value of said pixel for correction further comprises substituting said average pixel value of one of said first and second pixel pairs that has a lower difference pixel value.

31. A method of operating an imager, said imager having an array comprising a plurality of pixels, said method comprising:

locating a known defective pixel of a first color in said pixel array;

selecting a first plurality of neighboring pairs of pixels in said pixel array, wherein each pair of pixels of said first plurality of pairs of pixels comprises a first pixel having said first color and a second pixel having said first color on an opposite side of said known defective pixel than said first pixel;

determining if said first plurality of pairs of pixels includes any defective pixels; and

if said first plurality of pairs of pixels does not include any defective pixels;

determining an average pixel value for each pair of pixels in said first plurality of pairs of pixels; and

substituting an average pixel value of one of said pairs of pixels in said first plurality of pairs of pixels for a pixel value of said known defective pixel.

32. The method of claim 31, wherein if said first plurality of pairs of pixels does not include any defective pixels, said method further comprises:

determining a respective difference pixel value for each pair of pixels in said first plurality of pairs of pixels, wherein said respective difference pixel value for each pair of pixels comprises a difference between respective first and second pixels in said pair of pixels;

determining a lowest difference pixel value for said first plurality of pairs of pixels; and

substituting said average pixel value of said pair of pixels corresponding to said lowest difference pixel value for said pixel value of said known defective pixel.

33. The method of claim 31, wherein if said first plurality of pairs of pixels does not include any defective pixels, said method further comprises:

determining if a second plurality of pairs of pixels includes any defective pixels, wherein each pair of pixels of said second plurality of pairs of pixels comprises a first pixel having said first color and a second pixel having said first color on an opposite side of said known defective pixel than said first pixel; and

if said second plurality of pairs of pixels do not include any defective pixels;

determining an average pixel value for each pair of pixels in said second plurality of pairs of pixels; and

substituting an average pixel value of one of said pairs of pixels in said second plurality of pairs of pixels for said pixel value of said known defective pixel.

34. The method of claim 33, wherein if second plurality of pairs of pixels does not include any defective pixels, said method further comprises:

determining a respective difference pixel value for each pair of pixels in said second plurality of pairs of pixels, wherein said respective difference pixel value for each pair of pixels comprises a difference between respective first and second pixels in said pair of pixels;

determining a lowest difference pixel value for said second plurality of pairs of pixels; and

substituting said average pixel value of said pair of pixels corresponding to said lowest difference pixel value for said pixel value of said known defective pixel.

35. The method of claim 33, wherein if said second plurality of pairs of pixels includes at least one defective pixel, said method further comprises:

identifying a nearest non-defective pixel to said known defective pixel having said first color; and

substituting a pixel value of said nearest non-defective pixel for said pixel value of said known defective pixel.

36. The method of claim 31, wherein said first plurality of pairs of pixels includes a first pair of pixels comprising:

a first pixel having said first color located vertically above said known defective pixel in said array; and

a second pixel having said first color located vertically below said known defective pixel in said array.

37. The method of claim 36, wherein said first plurality of pairs of pixels further includes a second pair of pixels comprising:

a third pixel having said first color located horizontally on a first side of said known defective pixel in said array; and

a fourth pixel having said first color located horizontally on a second side of said known defective pixel in said array, wherein said second side is an opposite side of said known defective pixel than said first side.

38. The method of claim 33, wherein said second plurality of pairs of pixels includes a third pair of pixels comprising:

a fifth pixel having said first color; and

a sixth pixel having said first color, wherein said fifth and sixth pixels are located symmetrically surrounding said known defective pixel in said array.

39. The method of claim 38, wherein said second plurality of pairs of pixels further includes a fourth pair of pixels comprising:

a seventh pixel having said first color; and

an eighth pixel having said first color, wherein said seventh and eighth pixels are located symmetrically surrounding said known defective pixel in said array.

40. The method of claim 31, wherein said step of identifying a known defective pixel comprises identifying a pixel that is part of a cluster of defective pixels.

41. The method of claim 31, wherein said known defective pixel is designated by a fuse.

42. The method of claim 31, wherein said step of identifying a known defective pixel comprises locating said known defective pixel using processing circuitry.