Methods and apparatus for estimating orientation in an image
First Claim
1. A method of estimating an image orientation field, comprising:
- dividing an image into first partial regions;
measuring gradients of pixels of the image;
estimating representative orientations of the first partial regions;
filtering the image using a double orientation filter to form an improved image;
remeasuring the representative orientations of the first partial regions by remeasuring the gradients of the pixels of the improved image;
dividing the first partial regions into second partial regions; and
estimating representative orientations of the second partial regions with respect to curvature of the first partial regions in response to the remeasured representative orientations of the first partial regions and the remeasured gradients of the pixels.
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Abstract
Methods and apparatus for estimating an orientation are disclosed. Methods of estimating an orientation include: dividing a fingerprint image into first partial regions, measuring the gradient of each pixel of the fingerprint image, and estimating a representative orientation of each of the first partial regions; obtaining an improved fingerprint image by filtering the fingerprint image using a double orientation filter, and remeasuring the representative orientation of each of the first partial regions by remeasuring the gradient of each pixel of the improved fingerprint image; and dividing the first partial regions into second partial regions, and estimating the representative orientation of the second partial regions with respect to the curvatures of the first partial regions in response to the remeasured representative orientation of each of the first partial regions and the remeasured gradients of the pixels.
64 Citations
48 Claims
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1. A method of estimating an image orientation field, comprising:
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dividing an image into first partial regions;
measuring gradients of pixels of the image;
estimating representative orientations of the first partial regions;
filtering the image using a double orientation filter to form an improved image;
remeasuring the representative orientations of the first partial regions by remeasuring the gradients of the pixels of the improved image;
dividing the first partial regions into second partial regions; and
estimating representative orientations of the second partial regions with respect to curvature of the first partial regions in response to the remeasured representative orientations of the first partial regions and the remeasured gradients of the pixels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. An apparatus for estimating an orientation comprising:
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a partial region division unit configured to divide an image into first partial regions;
an orientation estimation unit configured to estimate a representative orientation of the first partial regions by measuring gradients of pixels of the image, configured to filter the image using a double orientation filter according to the estimated representative orientation, and configured to reestimate the representative orientation of the first partial regions by remeasuring the gradients of pixels of the improved image; and
an orientation reestimation unit configured to divide the first partial regions into second partial regions, and configured to estimate the representative orientations of the second partial regions with respect to curvatures of the first partial regions in response to the remeasured representative orientations of the first partial regions and the remeasured gradients of the pixels. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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Specification