Spoofed face detection

1. A computing device, comprising:

a processor configured to:

compute a first feature distance between registered image data of a human face in a first spectral region and test image data of the human face in the first spectral region;

compute a second feature distance between the registered image data of the human face in the first spectral region and test image data of the human face in a second spectral region;

compute a test feature distance between the test image data of the human face in the first spectral region and the test image data of the human face in the second spectral region;

determine, based on a predetermined relationship differentiating between real human face image data and spoofed human face image data, whether the human face to which the test image data in the first and second spectral regions corresponds is a real human face or a spoofed human face; and

modify a behavior of the computing device based on whether the human face is determined to be the real human face or the spoofed human face.

2. The computing device of claim 1 , wherein the predetermined relationship is determined by training a classifier to differentiate between real human face image data and spoofed human face image data classes in a two-dimensional feature distance space.

3. The computing device of claim 2 , wherein a first axis of the two-dimensional feature distance space plots a range of test feature distances, and

wherein a second axis of the two-dimensional feature space plots a range of differences between corresponding pairs of first and second feature distances.

4. The computing device of claim 2 , wherein the predetermined relationship compares a linear combination of the first, second, and test feature distances to a threshold, and

wherein the classifier is configured to determine that the human face is a real human face when the comparison exceeds the threshold, and to determine that the human face is a spoofed human face when the comparison falls below the threshold.

5. The computing device of claim 1 , wherein each feature distance is computed as a likelihood ratio of a probability of a respective pair of feature vectors belonging to the real human face and a probability of the respective pair of feature vectors belonging to the spoofed human face.

6. The computing device of claim 5 , wherein the feature vectors are computed based on local binary pattern analysis.

7. The computing device of claim 1 , wherein the first spectral region is an infrared spectral region, and

wherein the second spectral region is a visible spectral region.

8. The computing device of claim 1 , wherein it is determined that the human face to which the test image data in the first and second spectral regions corresponds is the real human face when the test feature distance exceeds a threshold.

9. The computing device of claim 1 , wherein it is determined that the human face to which the test image data in the first and second spectral regions corresponds is the real human face when the second feature distance exceeds the first feature distance.

10. The computing device of claim 1 , wherein computing the first, second, and test feature distances includes computing a respective pair of feature vectors, each feature vector encoding, for corresponding image data, one or more of a histogram of texture values, an edge, a point, a shape, and a brightness.

11. A method of biometric verification, comprising:

computing a first feature distance between registered image data of a human face in a first spectral region and test image data of the human face in the first spectral region;

computing a second feature distance between the registered image data of the human face in the first spectral region and test image data of the human face in a second spectral region;

computing a test feature distance between the test image data of the human face in the first spectral region and the test image data of the human face in the second spectral region;

determining, based on a predetermined relationship differentiating between real human image data and spoofed human image data, whether the human face to which the test image data in the first and second spectral regions corresponds is a real human face or a spoofed human face; and

modifying a behavior of a computing device based on whether the human face is determined to be the real human face or the spoofed human face.

12. The method of claim 11 , wherein the predetermined relationship is determined by training a classifier to differentiate between real human face image data and spoofed human face image data classes in a two-dimensional feature distance space.

13. The method of claim 12 , wherein a first axis of the two-dimensional feature distance space plots a range of test feature distances, and

wherein a second axis of the two-dimensional feature space plots a range of differences between corresponding pairs of first and second feature distances.

14. The method of claim 12 , wherein the predetermined relationship compares a linear combination of the first, second, and test feature distances to a threshold, and

wherein the classifier is configured to determine that the human face is a real human face when the comparison exceeds the threshold, and to determine that the human face is a spoofed human face when the comparison falls below the threshold.

15. The method of claim 11 , wherein each feature distance is computed as a likelihood ratio of a probability of a respective pair of feature vectors belonging to the real human face and a probability of the respective pair of feature vectors belonging to the spoofed human face.

16. The method of claim 15 , wherein the feature vectors are computed based on local binary pattern analysis.

17. The method of claim 11 , wherein the first spectral region is an infrared spectral region, and

wherein the second spectral region is a visible spectral region.

18. The method of claim 11 , wherein it is determined that the human face to which the test image data in the first and second spectral regions corresponds is the real human face when the test feature distance exceeds a threshold.

19. The method of claim 11 , wherein it is determined that the human face to which the test image data in the first and second spectral regions corresponds is the real human face when the second feature distance exceeds the first feature distance.

20. A computing device, comprising:

a processor; and

memory holding instructions executable by the processor to:

receive registered image data of a human face in a first spectral region;

receive test image data of the human face in the first spectral region;

receive test image data of the human face in a second spectral region;

for each of the registered image data, the test image data in the first spectral region, and the test image data in the second spectral region:

identify a plurality of regions of interest;

extract at least one feature from each of the plurality of regions of interest; and

assemble the extracted features into a feature vector;

compute a first feature distance between the feature vector of the registered image data and the feature vector of the test image data in the first spectral region;

compute a second feature distance between the feature vector of the registered image data and the feature vector of the test image data in the second spectral region;

compute a test feature distance between the feature vector of the test image data in the first spectral region and the feature vector of the test image data in the second spectral region;

in a two-dimensional feature distance space, separate the first, second, and test feature distances into one of a real human face image data class and a spoofed human face image data class; and

derive a classifier from the separated feature distances, the classifier configured to differentiate between real human face image data and spoofed human face image data.