Systems and methods for capturing artifact free images
View Patent ↗The present disclosure is directed towards methods and systems for capturing artifact-free biometric images of an eye. The eye may be in motion and in the presence of partially-reflective eyewear. The method may include acquiring, by a first sensor, a first image of an eye while the eye is illuminated by a first illuminator. The first image may include a region of interest. The first sensor may be disposed at a fixed displacement from the first illuminator and a second sensor. The second sensor may acquire, within a predetermined period of time from the acquisition of the first image, a second image of the eye. The second image may include the region of interest. An image processor may determine if at least one of the first and second images include artifacts arising from one or both of the first illuminator and eyewear, within the region of interest.
1. A method of acquiring artifact-free biometric images of an eye in relative motion with a sensor, and in the presence of partially-reflective eyewear, comprising:
(a) acquiring, by a first sensor, a first image of an eye while the eye is illuminated by a first illuminator, the first image including a region of interest, the first sensor disposed at a fixed displacement from the first illuminator and a second sensor;
(b) acquiring, by the second sensor within a predetermined period of time from the acquisition of the first image, a second image of the eye, the second image including the region of interest; and
(c) determining if at least one of the first and second images include an artifact within the region of interest arising from the first illuminator and eyewear, the artifact comprising a specular reflection off the eyewear within the region of interest and arising from the first illuminator.
2. The method of claim 1 , wherein (b) comprises acquiring, by the second sensor, the second image of the eye simultaneous with the acquisition of the first image.
3. The method of claim 2 , further comprising acquiring, by the first sensor, a third image of the eye while the eye is illuminated by a second illuminator disposed at a predefined distance from the first illuminator.
4. The method of claim 2 , further comprising acquiring, by the first sensor, within a predetermined time from the acquisition of the first image, a third image of the eye while the eye is illuminated by a second illuminator disposed at a vertical distance from the first illuminator.
5. The method of claim 1 , further comprising arranging the first and the second sensors such that the optical axes of the first and the second sensors converge at substantially a nominal distance, D, between the eye and the sensors.
6. The method of claim 5 , further comprising tilting the first and the second sensor at an angle, Theta, from a line connecting the eye and a midpoint between the first and second sensors, according to Theta=a Tan(0.5*S/D),
wherein S is a separation distance between the first and the second sensors, and D is a distance from the eye to the midpoint between the first and second sensors.
7. The method of claim 1 , further comprising selecting, based on the determination, at least a portion of the region of interest, from one or both of the first and second images, for use in biometric verification.
8. The method of claim 7 , further comprising combining the at least a portion of the region of interest selected, for biometric verification.
9. The method of claim 1 , further comprising determining if at least one of the first and second images includes at least one of: an obstruction from a non-lens portion of the eyewear, a discontinuity in a lens of the eyewear, or a distortion from a rim of the lens.
10. A system of acquiring artifact-free biometric images of an eye in relative motion with a sensor, and in the presence of partially-reflective eyewear, the system comprising:
a first illuminator;
a first sensor and a second sensor, the first sensor configured to acquire a first image of an eye while the eye is illuminated by a first illuminator, the first image including a region of interest, the first sensor disposed at a fixed displacement from the first illuminator and a second sensor,
the second sensor configured to acquire a second image of the eye within a predetermined period of time from the acquisition of the first image, the second image including the region of interest; and
an image processor configured to determine if at least one of the first and second images include an artifact within the region of interest arising from the first illuminator and eyewear, the artifact comprising a specular reflection off the eyewear within the region of interest and arising from the first illuminator.
11. The system of claim 10 , wherein the first sensor is vertically displaced with respect to the second sensor.
12. The system of claim 10 , wherein the second sensor is configured to acquire, simultaneous with the acquisition of the first image, the second image of the eye.
13. The system of claim 10 , wherein the first sensor is further configured to acquire a third image of the eye while illuminated by a second illuminator, the second illuminator disposed at a predefined distance from the first illuminator.
14. The system of claim 10 , further comprising a second illuminator disposed at a vertical distance from the first illuminator, wherein the first sensor is further configured to acquire, within a predetermined time from the acquisition of the first image, a third image of the eye while illuminated by the second illuminator.
15. The system of claim 14 , wherein the second sensor is further configured to acquire a fourth image of the eye while illuminated by the second illuminator.
16. The system of claim 10 , wherein the first and the second sensors are arranged such that the optical axes of the first and the second sensors converge at substantially a nominal distance, D, between the eye and the sensors.
17. The system of claim 16 , wherein the first and the second sensors are arranged such that the optical axes of the first and the second sensors are tilted at an angle, Theta, from a line connecting the eye and a midpoint between the first and second sensors, according to Theta=a Tan(0.5*S/D), and
wherein S is a separation distance between the first and the second sensors, and D is the distance from the eye to the midpoint between the first and second sensors.
18. The system of claim 10 , wherein the image processor is further configured to select, based on the determination, at least a portion of the region of interest, from one or both of the first and second images, for use in biometric verification.
19. The system of claim 18 , wherein the image processor is further configured to combine the at least a portion of the region of interest selected, for biometric verification.
20. The system of claim 10 , wherein the image processor is further configured to determine if at least one of the first and second images include at least one of: an obstruction from a non-lens portion of the eyewear, a discontinuity in a lens of the eyewear, or a distortion from a rim of the lens.