1. A method for compensating respiratory motion in coronary fluoroscopic images, the method comprising the steps of: finding a set of transformation parameters of a parametric motion model that minimize a weighted sum of square distances between a reference image acquired at a first time that is warped by the parametric motion model and a first incoming image acquired at a second time subsequent to the first time, wherein said weights are calculated as a ratio of a covariance of gradients of the reference image and gradients of the first incoming image with respect to a root of a product of a variance of the gradients of the reference image and the variance of the gradients of the first incoming image, and wherein the parametric motion model transforms the reference image to match the first incoming image.