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 km, 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;
processing the raw image;
accessing a wavelet base function, wherein the wavelet base function has a plurality of wavelet coefficients;
projecting at least a portion of the processed raw image on the wavelet base function;
identifying a plurality of modulated equalization coefficients from the projection; and
generating an iris code based on the plurality of modulated equalization coefficients.
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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
20 Claims
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1. A method of processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength km, comprising:
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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;processing the raw image; accessing a wavelet base function, wherein the wavelet base function has a plurality of wavelet coefficients; projecting at least a portion of the processed raw image on the wavelet base function; identifying a plurality of modulated equalization coefficients from the projection; and generating an iris code based on the plurality of modulated equalization coefficients. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength km, comprising:
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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;generating a polar coordinate iris image from the raw image; accessing a wavelet base function, wherein the wavelet base function has a plurality of wavelet coefficients; projecting at least a portion of the polar coordinate iris image on the wavelet base function; identifying a plurality of modulated equalization coefficients from the projection; and generating an iris code based on the plurality of modulated equalization coefficients. - View Dependent Claims (15, 16, 17, 18)
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19. A system for processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength KIM, comprising:
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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; anda controller electrically connected to the image sensor, wherein the controller is configured to access a wavelet base function, process the raw image, project at least a portion of the processed raw image on the wavelet base function, identify a plurality of modulated equalization coefficients from the projection, and generate an iris code based on the plurality of modulated equalization coefficients and the processed raw image, wherein the wavelet base function has a plurality of wavelet coefficients.
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20. A system for processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength KIM, comprising:
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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; anda controller electrically connected to the image sensor, wherein the controller is configured to access a wavelet base function, generate a polar coordinate iris image from the raw image, project at least a portion of the polar coordinate iris image on the wavelet base function, identify a plurality of modulated equalization coefficients from the projection, and generate an iris code based on the plurality of modulated equalization coefficients and the polar coordinate iris image, wherein the wavelet base function has a plurality of wavelet coefficients.
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Specification