FACE SEARCHING AND DETECTION IN A DIGITAL IMAGE ACQUISITION DEVICE

• US 20100272363A1
• Filed: 07/23/2007
• Published: 10/28/2010
• Est. Priority Date: 03/05/2007
• Status: Active Grant

• Current Assignee: FotoNation Limited (Adeia, Inc.)
• Original Assignee: FotoNation Vision Limited (Adeia, Inc.)
• Inventors: Bigioi, Petronel, Vasiliu, Andrei, Petrescu, Stefan Mirel, Steinberg, Eran, Gangea, Mihnea, Drimbarean, Alexandru, Corcoran, Peter, Costache, Gabriel
• Granted Patent: US 8,649,604 B2
• Time in Patent Office: Days
• US Class Current: 382/190
• CPC Class Codes: G06V 40/16 Human faces, e.g. facial parts, sketches or expressions
• CPC Class Codes: G06V 40/161 Detection; Localisation; Normalisation
• CPC Class Codes: G06V 40/162 using pixel segmentation or colour matching
• CPC Class Codes: G06V 40/164 using holistic features
• CPC Class Codes: G06V 40/168 Feature extraction; Face representation
• CPC Class Codes: G06V 40/172 Classification, e.g. identification

Abstract

A method of detecting a face in an image includes performing face detection within a first window of the image at a first location. A confidence level is obtained from the face detection indicating a probability of the image including a face at or in the vicinity of the first location. Face detection is then performed within a second window at a second location, wherein the second location is determined based on the confidence level.

Claims

1. One or more processor-readable media having code embedded therein for programming a processor to perform a method of detecting a face in an image comprising:

(a) performing face detection within a first relatively large window of said image at a first location;

(b) obtaining from said face detection a confidence level indicating a probability of that a face is present, that a face may be present, or that no face is present at or in the vicinity of said first location; and

(c) performing second face detection within a sequence of relatively smaller windows in the vicinity of said first location, wherein a direction or magnitude of displacement by an x-amount in a first direction and/or by a y-amount in an orthogonal second direction is variable between successive windows of said sequence eof windows within said image and wherein said x-amount and/or said y-amount is less for a confidence level indicating that the image at least may include a face in the vicinity of the first location.

3. One or more processor-readable media as claimed in claim 1, wherein the method further comprising repeating (a) to (c) for one or more additional windows in different locations until said performing face detection results in positive detection of a face.

4. One or more processor-readable media as claimed in claim 1 wherein the method further comprising repeating (a) to (c) for one or more additional windows in different locations until face detection has been performed over an entire region of interest.

5. One or more processor-readable media as claimed in claim 4, wherein the dimensions of said one or more additional windows depend on said confidence level.

6. One or more processor-readable media as claimed in claim 1, wherein the method further comprising repeating (a) to (c) until face detection for multiple predetermined sizes of windows has been performed over an entire region of interest of said image.

7. One or more processor-readable media as claimed in claim 1, wherein the method further comprising

determining a set of regions of interest for said image, and

repeating steps (a) to (c) for all said regions of interest.

8. One or more processor-readable media as claimed in claim 1, wherein the method further comprising identifying at least one region of said image likely to contain a face;

and repeating (a) to (c) until face detection is performed over substantially an entirety of said at least one region.

9. One or more processor-readable media as claimed in claim 1, wherein the method further comprising identifying at least one region of said image likely to contain a face;

and repeating (a) to (c) until face detection is performed concentrically inside said at least one region.

10. One or more processor-readable media as claimed in claim 1, wherein said face detection comprises applying a chain of classifiers to said windows of said image and wherein said confidence level comprises a function of a number of classifiers successfully applied to said windows.

12. One or more processor-readable media as claimed in claim 1, wherein said second location is determined by advancing said window in an x-amount in a first direction and in an orthogonal second direction by y-amount from the first location, wherein any overlap of the first and second windows is based on a said confidence level.

13. One or more processor-readable media as claimed in claim 12, wherein a size of the second window relative to a size of said first window is also based on said confidence level.

16. One or more processor-readable media as claimed in claim 1, wherein the x-amount or the y-amount, or both, are greater for a higher confidence level that the image does not include a face at the first location.

17. One or more processor-readable media as claimed in claim 1, wherein the x-amount and the y-amount depend separately on face detection confidence levels in the first and second directions, respectively.

18. One or more processor-readable media as claimed in claim 1, wherein when there is a confidence level above a threshold value that a face is detected in the vicinity of said first location, then the second location is selected such that the second window overlaps said first window to center on said face, and when there is a confidence level below said threshold, the second location is selected so that the second window does not overlap the first window.

19. One or more processor-readable media as claimed in claim 1, wherein the method further comprising pre-determining one or more regions of interest within the image each as having an enhanced likelihood of including a face, and locating a detection window at a suitable corner of each such region of interest, and applying (a) to (c) to each such region of interest.

20. One or more processor-readable media as claimed in claim 19, wherein (a) to (c) are applied to two or more regions of interest in time periods with at least some temporal overlap.

21. One or more processor-readable media as claimed in claim 19, wherein said one or more regions of interest comprise one or more regions including a number of skin pixels.

22. One or more processor-readable media as claimed in claim 19, wherein said image is an image in a stream of images and wherein said regions of interest comprise one or more regions in which a face has been detected in a previous image of said stream.

23. One or more processor-readable media as claimed in claim 1 wherein said step (c) comprises:

responsive to said confidence level indicating a face at or in the vicinity of said first location, performing detection of a frontally aligned face within a second window at a second location wherein said second location is determined based on a confidence level indicating a probability of a candidate region including said face at or in the vicinity of said first location.

24. One or more processor-readable media as claimed in claim 23 wherein the method further comprising:

(d) responsive to detection of a frontally aligned face in any candidate region, selectively applying face recognition to said candidate region.

25. One or more processor-readable media as claimed in claim 24 wherein face recognition is applied in response to any candidate region having a probability of including a face greater than a threshold.

26. One or more processor-readable media as claimed in claim 23 wherein said performing detection of a frontally aligned face is performed in a candidate region including said face detected at or in the vicinity of said first location.

27. One or more processor-readable media as claimed in claim 26 wherein performing detection of a frontally aligned face is performed in response to said candidate region having a probability of including a face greater than a first threshold.

28. One or more processor-readable media as claimed in claim 26 wherein the method further comprising:

responsive to said first location having a probability of including a face less than a first threshold, extracting an extended region including said first location from said image and performing face detection in said extended region with a relatively fine granularity to provide said candidate region.

29. One or more processor-readable media as claimed in claim 26 wherein the method further comprising:

responsive to a candidate region having a probability of including a face less than a second threshold, rotating an extended region including said face region through one of a sequence of angles and performing face detection in said rotated extended region with a relatively fine granularity to provide another candidate region.

30. One or more processor-readable media as claimed in claim 26 wherein the method further comprising:

responsive to a candidate region having a probability of including a face less than a second threshold, rotating said face within said extended region through one of a sequence of angles and performing face detection in said extended region with a relatively fine granularity to provide another candidate region.

2. (canceled)

11. (canceled)

14. (canceled)

15. (canceled)

31. A digital image processing device adapted to:

(a) perform first face detection within a first relatively large window of an acquired image at a first location;

(b) obtain from said face detection a confidence level indicating a probability that a face is present, that a face may be present, or that no face is present at or in the vicinity of said first location; and

(c) perform second face detection within a sequence of relatively smaller windows in the vicinity of said first location, wherein a direction or magnitude of displacement by an x-amount in a first direction and/or by a y-amount in an orthogonal second direction is variable between successive windows of said sequence of windows within said image and wherein said x-amount and/or said y-amount is less for a confidence level indicating that the image at least may include a face in the vicinity of the first location.

32. A method of detecting a face in an image, comprising:

(a) performing first face detection within a first relatively large window of said image at a first location;

(b) obtaining from said face detection a confidence level indicating a probability that a face is present, that a face may be present, or that no face is present at or in the vicinity of said first location; and

(c) performing second face detection within a sequence of relatively smaller windows in the vicinity of said first location, wherein a direction or magnitude of displacement by an x-amount in a first direction and/or by a y-amount in an orthogonal second direction is variable between successive windows of said sequence of windows within said image and wherein said x-amount and/or said y-amount is less for a confidence level indicating that the image at least may include a face in the vicinity of the first location.