Patent ID: 6912310
Filing Date: 2005-06-28
Classification: G06K,G06T

Abstract:
1. A method for estimating a desired contour of an image object which is tracked over a plurality of image frames, comprising the steps of: receiving a first estimate of the desired contour for a current image frame, the current image frame comprising image data, said first estimate comprising a plurality of data points; convolving said image data with a gradient operator in a first manner to derive a gradient magnitude; convolving said image data with the gradient operator in a second manner to derive a gradient direction; deriving a directional parameter for each one of said data points, wherein for each one of said data points said directional parameter has a value selected from a common range consisting of a first value and a second value, the first value corresponding to an inward convergence and the second value corresponding to an outward convergence, wherein said directional parameter is derived based upon a contour direction and a gradient direction from a prior image frame of the plurality of image frames; deriving a contour direction for each one of said data points for the current image frame; deriving external energy for each one of said data points based on said gradient magnitude, the corresponding contour direction and the corresponding directional parameter; and re-estimating the desired contour based at least in part on said derived external energy, in which the step of re-estimating comprises: for each one data point of said plurality of data points, testing, neighboring image data to identify a plurality of candidate data points which conform to the directional parameter of said corresponding each one data points; and selecting a path among the plurality data points and corresponding candidate points based on energy of the path.