Systems and methods for providing illumination for iris biometric acquisition
The present disclosure describes systems and methods for imaging an iris for biometric recognition. An image sensor may be located a distance L from an iris, to acquire an image of the iris. The image may have a contrast amplitude comprising modulation of a signal level at the image sensor due to features of the iris being acquired, and a standard deviation of said signal level due to noise generated within the image sensor. An illumination source may provide infrared illumination during acquisition of the image. When L is set at a value of at least 30 centimeters, the illumination source can provide the infrared illumination to the iris at a first irradiance value, quantified in watts per centimeter-squared, such that the contrast amplitude is at a value above that of the standard deviation, and enables the acquired image to be used for biometric recognition.
1. A system for imaging an iris for biometric recognition, the system comprising:
an image sensor located a distance L from an iris, the image sensor configured to acquire an image of the iris, the image having a contrast amplitude comprising modulation of a signal level at the image sensor due to features of the iris being acquired, and a standard deviation of said signal level due to noise generated within the image sensor; and
an illumination source configured to provide infrared illumination during acquisition of the image, wherein when L is set at a value of at least 30 centimeters, the illumination source is configured to provide the infrared illumination to the iris at a first irradiance value, such that the contrast amplitude is at a value above that of the standard deviation, and enables the acquired image to be used for biometric recognition.
2. The system of claim 1 , wherein the illumination source is configured to provide the infrared illumination at irradiance values with a variation of less than 50% below a corresponding peak irradiance value, at distances out to 60 centimeters, over an illumination field of at least ±23 degrees.
3. The system of claim 1 , wherein the illumination source is configured to provide the infrared illumination at irradiance values with a variation of less than 50% below a corresponding peak irradiance value, at distances out to 60 centimeters, over an illumination field of at least ±10 degrees.
4. The system of claim 1 , wherein the illumination source is configured to provide the infrared illumination at irradiance values of at least 0.0015 watts per centimeter-squared at distances out to 60 centimeters.
5. The system of claim 4 , wherein the illumination source is configured to provide the infrared illumination at irradiance values of at least 0.0015 watts per centimeter-squared at distances out to 60 centimeters, over an area with at least a radius of 5 centimeters.
6. The system of claim 4 , wherein the illumination source is configured to provide the infrared illumination at irradiance values of at least 0.0015 watts per centimeter-squared at distances out to 60 centimeters, over an area with at least a radius of 10 centimeters.
7. The system of claim 1 , wherein the illumination source comprises a light emitting diode (LED).
8. The system of claim 1 , wherein the image sensor and the illumination source are incorporated on a user device.
9. The system of claim 1 , wherein the standard deviation of said signal level is due to shot noise generated within the image sensor.
10. The system of claim 1 , wherein the first irradiance value is preconfigured or adjusted such that the contrast amplitude is at a value above that of the standard deviation.
11. A method for imaging an iris for biometric recognition, the method comprising:
locating an image sensor a distance L from an iris, the image sensor configured to acquire an image of the iris, the image having a contrast amplitude comprising modulation of a signal level at the image sensor due to features of the iris being acquired, and a standard deviation of said signal level due to noise generated within the image sensor; and
providing, by an illumination source, infrared illumination during acquisition of the image, wherein when L is set at a value of at least 30 centimeters, the illumination source is configured to provide the infrared illumination to the iris at a first irradiance value, such that the contrast amplitude is at a value above that of the standard deviation, and enables the acquired image to be used for biometric recognition.
12. The method of claim 11 , further comprising providing the infrared illumination at irradiance values with a variation of less than 50% below a corresponding peak irradiance value, at distances out to 60 centimeters, over an illumination field of at least ±23 degrees.
13. The method of claim 11 , further comprising providing the infrared illumination at irradiance values with a variation of less than 50% below a corresponding peak irradiance value, at distances out to 60 centimeters, over an illumination field of at least ±10 degrees.
14. The method of claim 11 , further comprising providing the infrared illumination at irradiance values of at least 0.0015 watts per centimeter-squared at distances out to 60 centimeters.
15. The method of claim 14 , further comprising providing the infrared illumination at irradiance values of at least 0.0015 watts per centimeter-squared at distances out to 60 centimeters, over an area with at least a radius of 5 centimeters.
16. The method of claim 14 , further comprising providing the infrared illumination at irradiance values of at least 0.0015 watts per centimeter-squared at distances out to 60 centimeters, over an area with at least a radius of 10 centimeters.
17. The method of claim 11 , wherein the illumination source comprises a light emitting diode (LED).
18. The method of claim 11 , wherein the image sensor and the illumination source are incorporated on a user device.
19. The method of claim 11 , wherein the standard deviation of said signal level is due to shot noise generated within the image sensor.
20. The method of claim 11 , wherein the first irradiance value is preconfigured or adjusted such that the contrast amplitude is at a value above that of the standard deviation.