RED-EYE FILTER METHOD AND APPARATUS

• US 20080211937A1
• Filed: 05/13/2008
• Published: 09/04/2008
• Est. Priority Date: 10/09/1997
• Status: Active Grant

• Current Assignee: FotoNation Limited (Adeia Inc.)
• Original Assignee: FotoNation Vision Limited (Adeia Inc.)
• Inventors: Steinberg, Eran, Prilutsky, Yury, Bigioi, Petronel, Corcoran, Peter, DeLuca, Michael J.
• Granted Patent: US 7,787,022 B2
• Time in Patent Office: Days
• US Class Current: 348/241
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/30201 Face
• CPC Class Codes: G06T 2207/30216 Redeye defect
• CPC Class Codes: G06T 5/008 Local, e.g. shadow enhancement
• CPC Class Codes: G06T 5/94 based on local image properties, e.g. for local contrast enhancement
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: G06V 40/162 using pixel segmentation or colour matching
• CPC Class Codes: G06V 40/165 using facial parts and geometric relationships
• CPC Class Codes: G06V 40/193 Preprocessing; Feature extraction
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature
• CPC Class Codes: H04N 1/62 Retouching, i.e. modification of isolated colours only or in isolated picture areas only
• CPC Class Codes: H04N 1/624 Red-eye correction control of camera based on recognised facial parts H04N23/611
• CPC Class Codes: H04N 23/63 by using electronic viewfinders
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/80 Camera processing pipelines; Components thereof
• CPC Class Codes: H04N 9/70 for colour killing

Abstract

A digital image acquisition system having no photographic film, such as a digital camera, has a flash unit for providing illumination during image capture and a red-eye filter for detecting a region within a captured image indicative of a red-eye phenomenon, the detection being based upon a comparison of the captured image and a reference image of nominally the same scene taken without flash. In the embodiment the reference image is a preview image of lower pixel resolution than the captured image, the filter matching the pixel resolutions of the captured and reference images by up-sampling the preview image and/or sub-sampling the captured image. The filter also aligns at least portions of the captured image and reference image prior to comparison to allow for, e.g. movement in the subject.

Claims

1. A portable digital camera having no photographic film, comprising:

(a) an integral flash for providing illumination during image acquisition;

(b) a digital image capturing apparatus including

(i) a main image sensor for acquiring a main image, and

(ii) a separate sensor for acquiring a low resolution image including a subsample representation of one or more selected regions of the main image; and

(c) a red-eye filter for correcting a red eye defect within the main image acquired by the main image sensor based on analysis of the low resolution image acquired by the separate sensor including the subsample representation of the one or more selected regions of the main image.

2. The camera of claim 1, further comprising a module for changing the degree of said subsampling.

3. The camera of claim 2, wherein said changing the degree of said subsampling is determined empirically.

4. The camera of claim 2, wherein said changing the degree of said subsampling is determined based on a size of said image.

5. The camera of claim 2, wherein said changing the degree of said subsampling is determined based on a region size.

6. The camera of claim 2, wherein said changing the degree of said subsampling is determined based on a complexity of calculation for said filter.

7. The camera of claim 1, wherein said subsample representation is determined using spline interpolation.

8. The camera of claim 1, wherein said subsample representation is determined using bi-cubic interpolation.

9. The portable digital camera of claim 1, wherein one or more low resolution images comprise at least one precapture image.

10. The portable digital camera of claim 9, wherein the precapture image is captured just before the main image is captured.

11. The portable digital camera of claim 1, further comprising one or more further filters for correcting exposure, focus or composition of the main image, or combinations thereof, based on analysis of the low resolution image acquired by the separate sensor.

12. The portable digital camera of claim 1, further comprising a filter for aligning the one or more low resolution images with the main image.

13. The portable digital camera of claim 12, wherein the aligning comprises estimating camera or object movement, or both, in one or more intervals between capture of the main and low resolution images.

14. The portable digital camera of claim 1, wherein the subsampled representation is generated in parallel with the main image.

15. The portable digital camera of claim 1, wherein the analysis of the low resolution image comprises identifying one or more red areas prior to activation of the flash and eliminating such areas from processing by the red eye filter.

16. The portable digital camera of claim 1, further comprising a dedicated hardware subsystem which is provided low resolution image data directly from the separate sensor.

17. The portable digital camera of claim 16, further comprising a main system memory which receives raw image data and metadata as implemented by the dedicated hardware subsystem.

18. The portable digital camera of claim 17, wherein the meta data comprises identified red areas determined not to be red eye regions.

19. The portable digital camera of claim 17, wherein the meta data comprises colors of regions that are not red prior to activation of the flash, wherein such regions appearing red in the main image are identified as having a certain enhanced probability of comprising red eye artifact.

20. A method of correcting a red eye defect within a digital image, comprising:

(a) providing a portable digital camera including a main image sensor for capturing a main image and a separate sensor for acquiring a low resolution image temporally proximate to acquisition of the main image;

(b) providing illumination during main image acquisition with a flash;

(c) acquiring a main image with the main image sensor;

(d) acquiring with the separate sensor a low resolution image temporally proximate to acquisition of the main image and including a subsample representation of one or more selected regions of the main image; and

(e) correcting a red eye defect within the main image acquired by the main image sensor based on an analysis of the low resolution image acquired by the separate sensor including the subsample representation of the one or more selected regions of the main image.

21. The method of claim 20, further comprising changing the degree of said subsampling.

22. The method of claim 21, further comprising determining the degree of said subsampling is empirically.

23. The method of claim 21, further comprising determining the degree of said subsampling based on a size of said image.

24. The method of claim 21, further comprising determining the degree of said subsampling based on a region size.

25. The method of claim 21, further comprising determining the degree of said subsampling based on a complexity of calculation for said filter.

26. The method of claim 20, further comprising determining said subsample representation using spline interpolation.

27. The method of claim 20, further comprising determining said subsample representation using bi-cubic interpolation.

28. The method of claim 20, further comprising capturing one or more low resolution images before capturing the main image.

29. The method of claim 20, further comprising correcting exposure, focus or composition of the main image, or combinations thereof, based on analysis of the low resolution image acquired by the separate sensor.

30. The method of claim 20, further comprising aligning the one or more low resolution images with the main image.

31. The method of claim 30, wherein the aligning comprises estimating camera or object movement, or both, in one or more intervals between capture of the main and low resolution images.

32. The method of claim 20, further comprising generating the subsampled representation in parallel with the main image.

33. The method of claim 20, further comprising identifying one or more red areas prior to activation of the flash and eliminating such areas from processing by the red eye filter.

34. The method of claim 20, further comprising providing low resolution image data directly from the separate sensor to a dedicated hardware subsystem.

35. The method of claim 34, further comprising receiving raw image data at a main image memory, along with metadata as implemented by the dedicated hardware subsystem.

36. The method of claim 35, wherein the metadata comprises identified red areas determined not to be red eye regions.

37. The method of claim 35, wherein the metadata comprises colors of regions that are not red prior to activation of the flash, wherein such regions appearing red in the main image are identified as having a certain enhanced probability of comprising red eye artifact.

38. One or more digital storage media having code embodied therein for programming one or more processors of a portable digital camera that includes a main image sensor and a separate low resolution sensor to perform a method of correcting a red eye defect within a digital image, wherein the method comprises:

(a) providing illumination during image acquisition with a flash;

(b) acquiring a main image with the main image sensor;

(c) acquiring with the separate sensor a low resolution image temporally proximate to acquisition of the main image and including a subsample representation of one or more selected regions of the main image; and

(d) correcting a red eye defect within the main image acquired by the main image sensor based on an analysis of the low resolution image acquired by the separate sensor including the subsample representation of the one or more selected regions of the main image.

39. The one or more storage media of claim 38, wherein the method further comprises changing the degree of said subsampling.

40. The one or more storage media of claim 39, wherein the method further comprises determining the degree of said subsampling is empirically.

41. The one or more storage media of claim 39, wherein the method further comprises determining the degree of said subsampling based on a size of said image.

42. The one or more storage media of claim 39, wherein the method further comprises determining the degree of said subsampling based on a region size.

43. The one or more storage media of claim 39, wherein the method further comprises determining the degree of said subsampling based on a complexity of calculation for said filter.

44. The one or more storage media of claim 38, wherein the method further comprises determining said subsample representation using spline interpolation.

45. The one or more storage media of claim 38, wherein the method further comprises determining said subsample representation using bi-cubic interpolation.

46. The one or more media of claim 38, wherein the method further comprises capturing one or more low resolution images before capturing the main image.

47. The one or more media of claim 38, wherein the method further comprises correcting exposure, focus or composition of the main image, or combinations thereof, based on analysis of the low resolution image acquired by the separate sensor.

48. The one or more media of claim 38, wherein the method further comprises aligning the one or more low resolution images with the main image.

49. The one or more media of claim 48, wherein the aligning comprises estimating camera or object movement, or both, in one or more intervals between capture of the main and low resolution images.

50. The one or more media of claim 38, wherein the method further comprises generating the subsampled representation in parallel with the main image.

51. The one or more media of claim 38, wherein the method further comprises identifying one or more red areas prior to activation of the flash and eliminating such areas from processing by the red eye filter.

52. The one or more media of claim 38, wherein the method further comprises providing low resolution image data directly from the separate sensor to a dedicated hardware subsystem.

53. The one or more media of claim 52, wherein the method further comprises receiving raw image data at a main image memory, along with metadata as implemented by the dedicated hardware subsystem.

54. The one or more media of claim 53, wherein the metadata comprises identified red areas determined not to be red eye regions.

55. The one or more media of claim 53, wherein the metadata comprises colors of non-red regions that are not red prior to activation of the flash, wherein such non-red regions appearing red in the main image are identified as having a certain enhanced probability of comprising red eye artifact.