A new method to correct the barral distortion of endoscope image based on the line search method of guaranteed global convergence is presented.A mathematical model based on polynomial mapping is used to map the image from the distortion image space onto the corrected image space.The model parameters include the polynomial coefficients,distortion center,and corrected center.The proposed method utilizes the imaging characteristics of an endoscope and a line search method of global convergence for the iterative procedure to obtain the optimum parameters.The experimental results using the proposed method have verified thatthe degree of the distortion correction is sufficient for improved diagnostic evaluation and provides high speed response and forms a key step toward online distortion correction,which is required for accurate quantitative analysis of the image.