PROCESSING AN IMAGE OF AN EYE
First Claim
1. A method of locating a boundary of an iris in a pixel-based image of an eye, the method comprising:
- comparing the values of each of a number of pixels along a plurality of lines across the image with a first threshold value in order to detect points along the lines at which the values of the pixels change to indicate the boundary of the iris of the eye; and
locating the boundary on the basis of the detected points.
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Accused Products
Abstract
An image of an eye is first captured and stored, as a 256 grey level image or as a colour image, and is then evaluated to determine thresholds between the values of pixels representing different parts of the eye. The thresholds are used to determine the boundary between the pupil and the iris and the boundary between the iris and the selera by determining the points at which lines across the image change their value with respect to a threshold value. Once the location of the iris has been found, the image is further processed to extract a biometric code from the iris using a linearisation procedure followed by a wavelet transformation. Finally, a biometric code is output by the processor.
43 Citations
75 Claims
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1. A method of locating a boundary of an iris in a pixel-based image of an eye, the method comprising:
- comparing the values of each of a number of pixels along a plurality of lines across the image with a first threshold value in order to detect points along the lines at which the values of the pixels change to indicate the boundary of the iris of the eye; and
locating the boundary on the basis of the detected points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- comparing the values of each of a number of pixels along a plurality of lines across the image with a first threshold value in order to detect points along the lines at which the values of the pixels change to indicate the boundary of the iris of the eye; and
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22. A method of generating a code based on the appearance of an iris in a pixel-based image of an eye, the method comprising:
- identifying an area of the image representing the iris;
generating a signal comprising values of a line of pixels extending around in a circumferential portion of the identified area; and
applying a wavelet filter to the signal to generate a frequency limited code based on the appearance of the iris. - View Dependent Claims (23, 24)
- identifying an area of the image representing the iris;
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25. An apparatus for locating a boundary of an iris in a pixel-based image of an eye, the apparatus comprising a processor that:
- compares the values of each of a number of pixels along a plurality of lines across the image with a first threshold value in order to detect points along the lines at which the values of the pixels change to indicate the boundary of the iris of the eye; and
locates the boundary on the basis of the detected points. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
- compares the values of each of a number of pixels along a plurality of lines across the image with a first threshold value in order to detect points along the lines at which the values of the pixels change to indicate the boundary of the iris of the eye; and
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46. An apparatus for generating a code based on the appearance of an iris in a pixel-based image of an eye, the apparatus comprising a processor that:
- identifies an area of the image representing the iris;
generates a signal comprising values of a line of pixels extending around in a circumferential portion of the identified area; and
applies a wavelet filter to the signal to generate a frequency limited code based on the appearance of the iris. - View Dependent Claims (47, 48)
- identifies an area of the image representing the iris;
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49. A method of processing a pixel-based image of an eye comprising the steps of:
- acquiring a pixel-based image of an eye;
evaluating the image to determine thresholds representing features of the eye;
scanning along a predetermined line and comparing with a first predetermined threshold so as to determine a first point at the boundary of the pupil;
conducting further scans in a plurality of predetermined directions from the first point so as to determine a plurality of second points at the boundary of the pupil and the iris;
identifying the centre of the pupil on the basis of the first and second points;
scanning along a further predetermined line and comparing with a second predetermined threshold so as to determine a third point at the boundary of the iris and the sclera; and
dividing the iris into a plurality of concentric zones and processing each zone in turn to produce a linear signal of predetermined length. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73)
- acquiring a pixel-based image of an eye;
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74. An apparatus for processing a pixel-based image of an eye comprising means for:
- acquiring a pixel-based image of an eye;
evaluating the image to determine thresholds representing features of the eye;
scanning along a predetermined line and comparing with a first predetermined threshold so as to determine a first point at the boundary of the pupil;
conducting further scans in a plurality of predetermined directions from the first point so as to determine a plurality of second points at the boundary of the pupil and the iris;
identifying the centre of the pupil on the basis of the first and second points;
scanning along a further predetermined line and comparing with a second predetermined threshold so as to determine a third point at the boundary of the iris and the sclera; and
dividing the iris into a plurality of concentric zones and processing each zone in turn to produce a linear signal of predetermined length.
- acquiring a pixel-based image of an eye;
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75-81. -81. (canceled)
Specification