Method and apparatus of correcting hybrid flash artifacts in digital images
View Patent ↗A method for digital image eye artifact detection and correction include identifying one or more candidate red-eye defect regions in an acquired image. For one or more candidate red-eye regions, a seed pixels and/or a region of pixels having a high intensity value in the vicinity of the candidate red-eye region is identified. The shape, roundness or other eye-related characteristic of a combined hybrid region including the candidate red-eye region and the region of high intensity pixels is analyzed. Based on the analysis of the eye-related characteristic of the combined hybrid region, it is determined whether to apply flash artifact correction, including red eye correction of the candidate red-eye region and/or correction of the region of high intensity pixels.
1. A digital camera, comprising:
(a) a lens;
(b) an image sensor;
(c) a processor and
(d) a computer readable medium having computer readable code embodied therein for programming the processor to perform a method of digital image artifact correction, the method comprising:
acquiring a digital image, including capturing a digital image using the lens and
the image sensor or receiving a digital image captured by an optical system of another device, or combinations thereof;
identifying a candidate red-eye defect region in said image;
identifying a region of high intensity pixels having at least a threshold intensity value within a sub-region of the image that also includes the candidate red-eye region;
analyzing an eye-related characteristic of the sub-region that comprises a combined hybrid region including said candidate red-eye region and said region of high intensity pixels;
identifying said combined hybrid region as a flash artifact region based on said analyzing of said eye-related characteristic; and
applying flash artifact correction to said flash artifact region.
2. The digital camera of claim 1 , the method further comprising defining a bounding box around said candidate red-eye defect region.
3. The digital camera of claim 1 , wherein identifying said region of high intensity pixels comprises identifying a seed high intensity pixel by locating said seed high intensity pixel within said bounding box.
4. The digital camera of claim 3 , wherein said seed pixel has a yellowness above a pre-determined threshold and a redness below a pre-determined threshold.
5. The digital camera of claim 3 , the method further comprising defining said region of high intensity pixels around said seed pixel.
6. The digital camera of claim 5 , wherein said analyzing comprises calculating a difference in roundness between said candidate red-eye region and said combined region.
7. The digital camera of claim 6 , wherein said red-eye correction is applied when said roundness of the combined hybrid region is greater than a threshold value.
8. The digital camera of claim 6 , the method further comprising determining to apply said red-eye correction when a roundness of the combined hybrid region is greater than a roundness of the candidate red-eye region by a threshold amount.
9. The digital camera of claim 5 , the method further comprising determining to not apply correction when said region of high intensity pixels comprises greater than a threshold area.
10. The digital camera of claim 9 , wherein said area is determined as a relative function to a size of said bounding box.
11. The digital camera of claim 5 , the method further comprising determining a yellowness and a non-pinkness of said region of high intensity pixels.
12. The digital camera of claim 11 , wherein said acquired image is in LAB color space, and wherein the method further comprises measuring an average b value of said region of high intensity pixels and determining a difference between an average a value and the average b value of said region of high intensity pixels.
13. The digital camera of claim 5 , wherein said analyzing further comprises analyzing said combined hybrid region for the presence of a glint, and determining to not correct said region of high intensity pixels responsive to the presence of glint.
14. The digital camera of claim 5 , the method further comprising correcting said region of high intensity pixels by selecting one or more pixel values from a corrected red-eye region and employing said pixel values to correct said region of high intensity pixels.
15. The digital camera of claim 14 , wherein said selected pixel values are taken from pixels having L and b values falling within a median for the corrected red-eye region.
16. The digital camera of claim 1 , the method further comprising determining to not apply correction when an average b value of said region of high intensity pixels exceeds a relatively low threshold or if a difference between average a and b values is lower than a pre-determined threshold.
17. The digital camera of claim 1 , the method further comprising converting said acquired image to one of RGB, YCC or Lb color space formats, or combinations thereof.
18. The digital camera of claim 1 , wherein said analyzing of said acquired image is performed in Luminance chrominance color space and said region of high intensity pixels has a luminance value greater than a luminance threshold, and blue-yellow chrominance values greater than a chrominance threshold and a red-green value less than a red-green threshold.
19. The digital camera of claim 1 , the method further comprising:
filtering said red-eye candidate regions to confirm or reject said regions as red-eye defect regions; and
selecting a subset of said rejected red-eye candidate regions for analysis as hybrid regions.
20. The digital camera of claim 1 , the method being implemented as part of an image acquisition process.
21. The digital camera of claim 1 , the method being implemented as part of a playback option in said digital camera.
22. The digital camera of claim 1 , the method being implemented to run as a background process in said digital camera.
23. The digital camera of claim 1 , the method being implemented within a general purpose computing device and wherein said acquiring comprises receiving said digital image from said digital camera.
24. The digital camera of claim 1 , wherein said flash artifact correction includes red eye correction of said candidate red-eye region.
25. The digital camera of claim 24 , wherein said flash artifact correction further comprises correction of said region of high intensity pixels.
26. The digital camera of claim 24 , wherein correcting said region of high intensity pixels comprises using corrected pixel values based on said candidate red-eye region.
27. The digital camera of claim 24 , wherein results of correcting said candidate red-eye region and said region of high intensity pixels are combined in such a manner as to obfuscate a seam between the regions.
28. The digital camera of claim 24 , the method further comprising smoothing a seam region between said candidate red-eye region and said region of high intensity pixels.
29. The digital camera of claim 1 , wherein said eye-related characteristic comprises shape.
30. The digital camera of claim 1 , wherein said eye-related characteristic comprises roundness.
31. The digital camera of claim 1 , wherein said eye-related characteristic comprises relative pupil size.
32. A digital camera, comprising:
(a) a lens,
(b) an image sensor,
(c)a processor and
(d) a computer readable medium having computer readable code embodied therein for programming the processor to perform a method of digital image artifact correction, the method comprising:
acquiring a digital image, including capturing a digital image using the lens and
the image sensor or receiving a digital image captured by an optical system of another device, or combinations thereof;
identifying a candidate red-eye defect region in said image;
identifying a seed pixel having a high intensity value within a sub-region of the image that also includes the candidate red-eye region;
analyzing an eye-related characteristic of the sub-region that comprises a combined hybrid region including said candidate red-eye region and said seed pixel;
identifying said combined hybrid region as a flash artifact region based on said analyzing of said eye-related characteristic; and
applying flash artifact correction to said flash artifact region.
33. The digital camera of claim 32 , wherein said seed pixel has a yellowness above a pre-determined threshold and a redness below a pre-determined threshold.
34. The digital camera of claim 32 , the method further comprising:
filtering said red-eye candidate regions to confirm or reject said regions as red-eye defect regions; and
selecting a subset of said rejected red-eye candidate regions for analysis as hybrid regions.
35. The digital camera of claim 32 , the method being implemented as part of an image acquisition process.
36. The digital camera of claim 32 , the method being implemented as part of a playback option in said digital camera.
37. The digital camera of claim 32 , the method being implemented to run as a background process in said digital camera.
38. The digital camera of claim 32 , the method being implemented within a general purpose computing device and wherein said acquiring comprises receiving said digital image at said digital camera.
39. The digital camera of claim 32 , wherein the analyzing comprises checking whether an average b value exceeds a relatively low threshold.
40. The digital camera of claim 39 , wherein the analyzing comprises checking whether a difference between an average a value and the average b value is lower than a given threshold.
41. The digital camera of claim 32 , wherein said flash artifact correction includes red eye correction of said candidate red-eye region.
42. The digital camera of claim 32 , wherein said flash artifact correction further comprises correction of a second region that includes said seed pixel.