Iris Recognition Using Consistent Corner Optical Flow

[A] Inner boundary localization: Edges are obtained over thresholded image using Sobel filters. Hough transform is improved by using the orientation of each pixel to reduce the search space from 3D i.e 3-tuple < x, y, r > to 1D of the radius only. It makes use of the key observation that “if an edge point lies on a circle, then the center of circle should lie on the normal to the edge direction (orientation) at that point”. Thus, for an edge point (x, y) in an image and for a radius r, the center coordinates (c1 , c y 1) and (c2 , c y 2), for two circles (one to its left and other to right half) can be computed as: