Abstract: An investigation of some approaches to digital image technique in measuring and controlling MAG welding arc was conducted. In this research work, the authors controlled the arc for improving the welding quality, using an optica welding robot. The control system consisted of TV-camera, microcomputer and image memory. The arc length was taken as the manipulated quantity in the system and the peak current width of welding pulse was varied. The result of the study offers a new and feasible method for the automatic MAG welding.