Accurate estimation of elliptical shape parameters from a grey-level image

The main sources of errors that cause distortion in the shape of an ellipse are presented, and methods for compensation of these distortion factors are formulated. A method for estimation of ellipse center coordinates is proposed. A method for the determination of an optimal elliptical fit to a set of input-edge-points is presented. An error function, based on a new geometrical interpretation of an existing error function, for estimation of all five parameters of an ellipse is defined, and an objective and independent measure for the goodness of various fits is given. The proposed error function and two other previously developed error functions are applied to six different situations. The results of the comparative study show that when all the edge points are used for the fit, the performance of the proposed error function is better than the other two