The present disclosure proposes an image processing method, a vision system, a fault locating method and a motor vehicle. Through the addition of markers when each processing unit is subjecting an image signal to processing, the markers corresponding thereto and being distinguishable from one another on an image frame of a final image signal, there are advantages of simple, convenient and quick fault locating, and low development, maintenance and debugging costs. Furthermore, because the markers are added to the image frame of the final image signal at a suitable frame rate and in a suitable form, there are further advantages of not affecting the original functions of the vision system and not disturbing the motor vehicle driver. Moreover, because the markers are widely distributed on the image frame of the final image signal to comprehensively reflect faults in the image frame of the final image signal without omission, there is the further advantage of high sensitivity in fault detection.