Patent ID: 7397938
Filing Date: 2008-07-08
Classification: G06K

Abstract:
1. A method of identifying spherical objects in a digital image, wherein said image comprises a plurality of intensities corresponding to a domain of points in a D-dimensional space, said method comprising the steps of: calculating a local cross-correlation between a point in the domain of the image and a Gaussian spatial filter G wherein I(p) is the image at the point p, G N G K =K.G N,K with being constant, and * is a convolution operator; calculating a local standard deviation of the point in the image; calculating a local standard deviation of the spatial filter; calculating a cross-correlation ratio by dividing the local cross-correlation by the product of the local standard deviation of the image and the local standard deviation of the spatial filter; and analyzing the cross-correlation ratio to determine whether an object about said point is spherically symmetric.