According to the gray distribution character of vignetting image

the method of Gaussian quadrics fitting based on steepest descent method is introduced in this paper.Parameters of Hesse matrix are also deduced at the same time

and then the problem of irregular Gaussian quadrics fitting is solved.By this method

the whole gray change of image is achieved

so the vignetting phenomenon is corrected.The simulation result illuminated that the parameters of irregular Gaussian quadrics

such as vignetting image gray level

can be estimated effectively by this method.The actual processing result shows the vignetting phenomenon can be removed effectively

and consequently the quality of image is improved.Since no relative optical and geometrical parameters are needed

this method can be widely used in projects.