Iris-based biometric identification
A method includes forming a feature vector associated with an iris of an individual using a transform operation including converting an iris image into a log-polar image, scaling one or more samples in the log-polar image according to a Fourier-Mellin transform, and performing a Fourier transform on the scaled samples. The method involves forming an iris digest based on the feature vector, and creating a biometric identifier based on the iris digest. A system includes an iris scanner, an iris analyzer that forms an image of a human iris wherein the presence of eyelashes in the image is minimized, forms a feature vector associated with the iris image using a modified Fourier-Mellin transform, and compresses the feature vector into an iris digest.
1. A method comprising:
forming a feature vector associated with an iris of an individual using a transform operation including:
converting an image of the iris into a log-polar image,
scaling one or more samples in the log-polar image with a Fourier-Mellin transform scalar exponential,
performing a Fourier transform on the log-polar image;
forming an iris digest based on the feature vector; and
creating a biometric identifier based on the iris digest.
2. A method as recited in claim 1 , wherein the biometric identifier is a document.
3. A method as recited in claim 1 , wherein the biometric identifier is an identity card.
4. A method as recited in claim 1 , wherein the scaling is applied in a radial direction of the iris.
5. A method as recited in claim 1 , wherein the converting comprises:
sampling the iris image logarithmically in a radial direction of the iris; and
sampling the iris image uniformly in an annular direction of the iris.
6. A method as recited in claim 1 , wherein the scaling is applied in a radial direction of the iris, and wherein the Fourier transform is applied along an annular direction of the iris.
7. A method as recited in claim 1 , wherein the transform operation is carried out in a discrete domain.
8. A method as recited in claim 1 , wherein the transform operation further comprises:
creating a rectangular representation of the iris; and
masking regions in the rectangular representation that do not include iris data.
9. A method as recited in claim 1 , wherein forming the iris digest based on the feature vector includes compressing the feature vector.
10. A method as recited in claim 1 further comprising:
detecting a pupil in the iris image;
detecting an iris annulus around the iris in the iris image; and
removing noise from the iris image, the noise being due to elements in the iris image other than the iris.
11. A method as recited in claim 1 wherein the feature vector is generated using a distance metric that characterizes a numerical difference between the iris and a reference iris.
12. A computer-readable medium having stored thereon computer-executable instructions for causing a computer to perform a process comprising:
forming an isolated iris image from an image of an eye of an, individual;
forming an iris digest based on the isolated iris image using a transform operation including:
converting isolated iris image into a log-polar image,
scaling one or more samples in the log-polar image according to a Fourier-Mellin transform,
performing a Fourier transform on the log-polar image; and
creating a biometric identifier based on the iris digest.
13. A computer-readable medium as recited in claim 12 , wherein forming an isolated iris image comprises:
detecting a pupil in the image of the eye;
detecting an iris annulus around an edge of the iris in the image of the eye;
removing noise from the image of the eye around the iris annulus.
14. A computer-readable medium as recited in claim 12 , the process further comprising:
hashing text descriptive of the individual; and
combining the hashed text with the iris digest.
15. A computer-readable medium as recited in claim 12 , the process further comprising signing the biometric identifier with a private-key.
16. A computer-readable medium as recited in claim 12 , the process further comprising encoding the biometric identifier in a barcode.
17. A computer-readable medium as recited in claim 12 , the process further comprising:
encoding the biometric identifier in a barcode; and
printing the barcode on a document.
18. A computer-readable medium as recited in claim 12 , the process further comprising:
hashing text descriptive of the individual;
combining the hashed text with the iris digest;
including the combined hashed text and the iris digest in the biometric identifier;
signing the biometric identifier with a private-key; and
encoding the biometric identifier in a barcode.
19. A computer-readable medium as recited in claim 12 , wherein forming the iris digest further includes creating a feature vector based on the Fourier transform.
20. A computer-readable medium as recited in claim 12 , wherein forming the iris digest further includes creating a feature vector by selecting one or more Fourier transform coefficients generated from the Fourier transform.
21. A computer-readable medium as recited in claim 12 , wherein the scaling is applied in a radial direction of the iris, and wherein the Fourier transform is applied along an annular direction of the iris.
22. A computer-readable medium as recited in claim 12 , wherein the process further comprises forming a face digest from an image of a face of the individual.
23. A computer-readable medium as recited in claim 12 , wherein the process further comprises forming a face digest from an image of a face of the individual, and wherein the creating a biometric identifier comprises creating a biometric identifier based on the iris digest and the face digest.