A procedure for removing the linear and nonlinear distortion in side scanning sonar records is described. The sonographs are placed on one rotating drum and optically scanned. The optical signal is converted to an electrical voltage and marks an electrosensitive paper on the second drum. The two drums have a common shaft and rotate together. The position and rate of scan of the marking stylus is controlled to remove the distortion. An example of a distorted and corrected sonograph is shown.