SYSTEM AND METHOD FOR IRIS DATA ACQUISITION FOR BIOMETRIC IDENTIFICATION
A system and related method for acquiring high quality images of the iris of an unconstrained subject comprising a camera; a controllable focusing component; a focus controller component that controls the lens to focus at successively different points within a focus range, such focus control performed without any input from measurement of whether the image is in focus or out of focus, be it based from measurements of the image or other distance metrics to the subject; and a sharpness detection component that rejects the most out-of-focus images based on measurement of focus on the image is disclosed.
1 . A method for acquiring a series of images of a unconstrained subject, the method comprising:
(a) acquiring, by a sensor without input from measurement of whether an image of an unconstrained subject to be acquired is in focus, the image of the unconstrained subject;
(b) determining, based on the acquired image, a time period during which there is a high probability that biometric data from the unconstrained subject is available for acquisition; and
(c) initiating acquisition of a series of images by the sensor within the determined time period, each image acquisition corresponding to a focus value within a predefined focus range, without input from measurement of whether a corresponding image to be acquired is in focus.
2 . The method of claim 1 , wherein (b) further comprises detection of a feature of the subject's face or eye on the acquired image.
3 . The method of claim 1 , wherein (b) further comprises detection of one of: an eye or iris that is open but blurred in the acquired image, and an eye or iris that is partially open in the acquired image.
4 . The method of claim 1 , wherein (b) further comprises measuring at least one of sharpness and contrast of the acquired image.
5 . The method of claim 1 , wherein (b) comprises determining the time period based on at least one of: a result of biometric matching using the acquired image, and detection of a physical feature or motion of the subject from the acquired image.
6 . The method of claim 1 , comprising configuring the sensor for operation with a single focus lens or using a single focus setting.
7 . The method of claim 1 , further comprising determining at least one of: a duration for the time period, an image acquisition rate, and a number of images, for the acquisition of the series of images.
8 . The method of claim 1 , further comprising determining, based on an estimated degree of motion of the subject, at least one of: a duration for the time period, a rate for acquisition and a number of images, for the acquisition of the series of images.
9 . The method of claim 1 , wherein (c) comprises acquiring the series of images at focus values substantially according to one of a monotonic, sawtooth, and random scan pattern.
10 . The method of claim 1 , further comprising rejecting at least one image from the series of acquired images, based on one or more of: a result of biometric matching, measurement of image sharpness, measurement of image contrast, and detection of a feature of the subject's eye.
11 . A system for acquiring a series of images of a unconstrained subject, the system comprising:
a sensor, acquiring, without input from measurement of whether an image of an unconstrained subject to be acquired is in focus, the image of the unconstrained subject;
a controller, determining, based on the acquired image, a time period during which there is a high probability that biometric data from the unconstrained subject is available for acquisition, and initiating acquisition of a series of images by the sensor within the determined time period, each image acquisition corresponding to a focus value within a predefined focus range, without input from measurement of whether a corresponding image to be acquired is in focus.
12 . The system of claim 11 , wherein the controller detects a feature of the subject's face or eye on the acquired image.
13 . The system of claim 11 , wherein the controller detects one of: an eye or iris that is open but blurred in the acquired image, and an eye or iris that is partially open in the acquired image.
14 . The system of claim 11 , wherein the controller measures at least one of sharpness and contrast of the acquired image.
15 . The system of claim 11 , wherein the controller determines the time period based on at least one of: a result of biometric matching using the acquired image, and detection of a physical feature or motion of the subject from the acquired image.
16 . The system of claim 11 , wherein the sensor is configured for operation with a single focus lens or using a single focus setting.
17 . The system of claim 11 , wherein the controller determines at least one of: a duration for the time period, an image acquisition rate, and a number of images, for the acquisition of the series of images.
18 . The system of claim 11 , wherein the controller determines, based on an estimated degree of motion of the subject, at least one of: a duration for the time period, a rate for acquisition and a number of images, for the acquisition of the series of images.
19 . The system of claim 11 , wherein the sensor acquires the series of images at focus values substantially according to one of a monotonic, sawtooth, and random scan pattern.
20 . The system of claim 11 , wherein the controller rejects at least one image from the series of acquired images, based on one or more of: a result of biometric matching, measurement of image sharpness, measurement of image contrast, and detection of a feature of the subject's eye.