Extended depth-of-field biometric system
First Claim
Patent Images
1. A method of processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
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IM, comprising;
capturing a raw image of the iris, wherein the raw image has a reduced modulation transfer function (MTF) based on an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM;
normalizing the raw image;
performing an MTF enhancement of the normalized raw image in polar coordinates to generate a MTF enhanced image; and
generating an iris code from the MTF enhanced image.
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Abstract
An iris recognition system may include an optical system having an intentional amount of spherical aberration that results in an extended depth of field. A raw image of an iris captured by the optical system may be normalized. In some embodiments, the normalized raw image may be processed to enhance the MTF of the normalized iris image. An iris code may be generated from the normalized raw image or the enhanced normalized raw image. The iris code may be compared to known iris codes to determine if there is a match.
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Citations
34 Claims
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1. A method of processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
-
IM, comprising;
capturing a raw image of the iris, wherein the raw image has a reduced modulation transfer function (MTF) based on an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM;normalizing the raw image; performing an MTF enhancement of the normalized raw image in polar coordinates to generate a MTF enhanced image; and generating an iris code from the MTF enhanced image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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IM, comprising;
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18. A system for processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
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IM, comprising;
an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM, the optical system being configured to form on an image sensor a raw image having reduced a modulation transfer function (MTF) based on the spherical aberration;a controller electrically connected to the image sensor, wherein the controller is configured to capture a raw image of the iris from the optical system, normalize the raw image, perform an MTF enhancement of the normalized raw image in polar coordinates to generate a MTF enhanced image, and generate an iris code from the MTF enhanced image. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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IM, comprising;
Specification