A new Differential Rectification Method (DRM) for frame cameras is proposed by Karslioglu and Friedrich  for the generation of orthoimages from monoscopic digital images which map every pixel onto a curved surface of reference frame i.e. WGS84. The ellipsoidal geodetic coordinates, of each pixel are calculated directly under the condition that a precise enough elevation model is available avoiding additional earth curvature corrections after the rectification. In this paper, convergence of the differential rectification method (DRM) is improved and its rectification accuracy is compared with five of the existing methods. Interior and exterior camera and atmospheric refraction parameters are taken into account in the rectification procedure of DRM. Additionally, effect of inclined camera direction and threshold value assigned for convergence criteria of DRM on the number of iterations and rectified coordinates are examined. It is seen that the accuracy of DRM is considerably better than the tested methods which indicates that DRM can be used by confidence. Furthermore, assigning too small threshold value does not improve the rectification results but however it increases the required number of iterations for the convergence of the relief displacement algorithm.