Multimodal ocular biometric system and methods
First Claim
1. A method for segmenting a biometric characteristic from an eye image captured by a biometric device, the method comprising the steps of:
- defining one or more first search windows in a captured eye image;
identifying a first set of points corresponding to peaks in an image intensity gradient in each of the one or more first search windows;
determining, from the first set of points, segments according to image intensity transitions, each segment having a center point;
determining a position for the center point of each segment;
grouping sets of the segments into a first set of clusters according to an analysis of the positions of the center points for the segments; and
selecting, from the first set of clusters, a second set of clusters corresponding to a pupil image;
fitting a first model template to the points for each set of segments corresponding to the second set of clusters, the fitted first model template corresponding to an initial pupil outer boundary for the pupil image;
defining one or more second search windows in relation to the initial pupil outer boundary;
identifying a second set of points corresponding to peaks in an image intensity gradient in each of the one or more second search windows; and
fitting a second model template to the second set of points, the fitted second model template corresponding to a refined pupil outer boundary for the pupil image.
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Abstract
Biometric systems capture and combine biometric information from more than one modality, employing digital processing algorithms to process and evaluate captured images having data for a biometric characteristic. Such digital algorithms may include a pupil segmentation algorithm for determining a pupil image in the captured image, an iris segmentation algorithm for determining an iris image in the captured image, an eyelid/eyelash segmentation algorithm for determining an eyelid/eyelash image in the captured image, and an algorithm for measuring the focus on the iris. Some embodiments employ an auto-capture process which employs such algorithms, in part, to evaluate captured images and obtain the best possible images for biometric identification.
91 Citations
14 Claims
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1. A method for segmenting a biometric characteristic from an eye image captured by a biometric device, the method comprising the steps of:
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defining one or more first search windows in a captured eye image; identifying a first set of points corresponding to peaks in an image intensity gradient in each of the one or more first search windows; determining, from the first set of points, segments according to image intensity transitions, each segment having a center point; determining a position for the center point of each segment; grouping sets of the segments into a first set of clusters according to an analysis of the positions of the center points for the segments; and selecting, from the first set of clusters, a second set of clusters corresponding to a pupil image; fitting a first model template to the points for each set of segments corresponding to the second set of clusters, the fitted first model template corresponding to an initial pupil outer boundary for the pupil image; defining one or more second search windows in relation to the initial pupil outer boundary; identifying a second set of points corresponding to peaks in an image intensity gradient in each of the one or more second search windows; and fitting a second model template to the second set of points, the fitted second model template corresponding to a refined pupil outer boundary for the pupil image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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