Real-time facial recognition and verification system

• US 20030059124A1
• Filed: 03/19/2002
• Published: 03/27/2003
• Est. Priority Date: 04/16/1999
• Status: Abandoned Application

• Current Assignee: Viisage Technology, Inc. (Advent International Corporation)
• Original Assignee: Viisage Technology, Inc. (Advent International Corporation)
• Inventors: Center, Julian
• Application Number:
  US10/102,087
• Publication Number:
  US 20030059124A1
• Time in Patent Office: Days
• US Class Current: 382/278
• CPC Class Codes: G06V 40/162 using pixel segmentation or colour matching
• CPC Class Codes: G06V 40/169 Holistic features and representations, i.e. based on the facial image taken as a whole
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

A system and method for acquiring, processing, and comparing an image with a stored image to determine if a match exists. The system employs a transformation into the frequency domain to more efficiently correlate the acquired image with the set of stored images. The image and stored image pair with the highest correlation value is considered to be the best matched pair. The facial recognition system determines the match in substantially real time. In particular, the present invention employs a motion detection stage, blob stage and a color matching stage at the input to localize a region of interest (ROI) in the image. The ROI is then processed by the system to locate the head, and then the eyes, in the image by employing a series of templates, such as eigen templates. The system then thresholds the resultant eigenimage to determine if the acquired image matches a pre-stored image.

Claims

1. A method for identifying a subimage within an image, the method comprising

representing the image as a function I(x) of a first pixel location x;

mapping the function I(x) to a standardized function p(x, y) of the first pixel location x, and a second pixel location y;

obtaining at least one coefficient from the standardized function and a set of reference images; and

utilizing the at least one coefficient to match the subimage to the set of reference images to identify the subimage.

2. The method of claim 1, wherein, in the step of mapping, the standardized function has a brightness and a contrast that are substantially equal to at least one member of the set of reference images.

3. The method of claim 2, wherein, in the step of correlating, the standardized function is given by

4. The method of claim 1, wherein, in the step of obtaining, each of the at least one coefficient, represented by Ω

_k(y), is given by

5. The method of claim 4, further comprising allowing y to vary to minimize a matching function of the Ω

_k(y).

6. The method of claim 4, wherein the subimage is identified within the image, and further comprising the step of comparing the matching function to a threshold value.

7. The method of claim 4, wherein, in the step of obtaining, each eigenfunction, u_k(x), is associated with a covariance matrix.

8. The method of claim 1, wherein the step of obtaining includes transforming I(x) to yield a transform I(ω

) from which the correlation coefficient is computed.

9. The method of claim 8, wherein, in the step of obtaining, the at least one correlation coefficient, Ω

_k(y), is given by

Ω

_k(y)=F<sup>−

1</sup>[I(ω

)uws_k(ω

)]/s(y)

when S_R=0 and m_R=0, where

10. The method of claim 9, wherein, in the step of correlating, the transform is a Fourier transform.

19. The system of claim 18, wherein the at least one correlation coefficient, Ω

_k(y), is given by

Ω

_k(y)=F<sup>−

1</sup>[I(ω

)uws_k(ω

)]/s(y)

when S_R=0 and m_R=0, where

20. The system of claim 19, wherein the transform is a Fourier transform.

11. A system for identifying a subimage within an image, the system comprising

an image acquisition stage for representing the image as a function I(x) of a first pixel location x;

an image manipulation stage for mapping the function I(x) to a standardized function p(x, y) of the first pixel location x, and a second pixel location y;

a compression stage for obtaining at least one coefficient from the standardized function and a set of reference images; and

a discrimination stage for utilizing the at least one coefficient to match the subimage to the set of reference images to identify the subimage.

12. The system of claim 11, wherein the standardized function has a brightness and a contrast that are substantially equal to at least one member of the set of reference images.

13. The system of claim 12, wherein the standardized function is given by

14. The system of claim 11, wherein each of the at least one coefficient, represented by Ω

_k(y), is given by

15. The system of claim 14, wherein y is allowed to vary to minimize a matching function of the Ω

_k(y).

16. The system of claim 14, wherein the subimage is identified within the image if the matching function is less than a threshold value.

17. The system of claim 14, wherein each eigenfunction, u_k(x), is associated with a covariance matrix.

18. The system of claim 11, wherein the step of obtaining includes transforming I(x) to yield a transform I(ω

) from which the correlation coefficient is computed.

21. A method for identifying an object, the method comprising

obtaining an image function of the object;

calculating a transform of the image function;

obtaining an eigenfunction from a set of reference functions;

obtaining a coefficient from the transform of the image function and the eigenfunction; and

utilizing said coefficient to match the image function for identifying the object.

22. The method of claim 21, wherein the image function corresponds to an intensity as a function of pixel location.

23. The method of claim 22, wherein the step of calculating includes obtaining a Fourier transform.

24. The method of claim 23, wherein the step of obtaining an eigenfunction includes obtaining a covariance matrix from the set of reference functions.

25. The method of claim 24, wherein the step of utilizing includes determining whether a norm is less than a configurable threshold.

26. A system for identifying an object, the system comprising

a transform stage for calculating a transform of an image function of the object;

a compression stage for obtaining an eigenfunction from a set of reference functions, and for obtaining a coefficient from the transform of the image function and the eigenfunction; and

a discrimination stage for utilizing said coefficient to match the image function for identifying the object.

27. The system of claim 26, wherein the image function corresponds to an intensity as a function of pixel location.

28. The system of claim 27, wherein the transform stage obtains a Fourier transform.

29. The system of claim 28, wherein the compression stage obtains the eigenfunction from a covariance matrix obtained from the set of reference functions.

30. The system of claim 29, wherein the discrimination stage determines whether a norm is less than a configurable threshold.