The initial contour for all other frames was the final contour of the previous frame. The algorithm is extremely sensitive to parameter choices. The paremeters alpha, beta and gamma specify the relative importance of the energy terms E cont , E curv and E image in computing the overall energy at a point. Alpha controls how evenly spaced the points in the contour will be because E cont is high for segments that are much shorter than or much longer than the mean distance between points. Large Alpha ensures that the points remain evenly spaced on the contour.
Beta controls the curvature of the contour.
Large Beta keeps the contour smooth except at corners. Gamma controls the influence of image gradients on energy. When there is little noise in the image, a large value of Gamma is useful in making the curve converge faster. Thresholds 1 and 2 determine when corners are created. When the final desired contour is known to be circular, set large values for these parameters.