Patent ID: 6690842
Filing Date: 2004-02-10
Classification: G06T

Abstract:
An apparatus for detection and sub-pixel location of edges in a digital image, said digital image including a plurality of pixel values, each pixel value being associated with a respective pixel point of a regularly-spaced pixel grid, said apparatus comprising:a gradient estimator for estimating gradient magnitude and gradient direction at a plurality of regularly-spaced gradient points in said digital image, so as to provide a plurality of estimates of gradient magnitude and gradient direction, each said estimate of gradient magnitude and gradient direction being associated with a respective gradient point of a regularly-spaced gradient grid; a peak detector, cooperative with said gradient estimator, operating such that gradient magnitude associated with each gradient point is used to select a plurality of gradient points that substantially have a local maximum of gradient magnitude in approximately said gradient direction; and a subpixel interpolator, cooperative with said gradient estimator and said peak detector, operating such that gradient direction associated with each gradient point is used to select a respective set of neighboring gradient points, and operating such that said local maximum of gradient magnitude and the gradient magnitudes of the respective set of neighboring gradient points are used to determine an interpolated edge position along a one-dimensional gradient magnitude profile including a gradient point associated with said local maximum of gradient magnitude and each gradient point associated with said respective set of neighboring gradient points.