An image-processing unit, a system, an automatic loading and/or unloading system and a method for detecting a locking device on a movable object, wherein the locking device locks a plurality of movable objects to one other and is arranged in a locking region of the movable object and the movable object is moved via a loading device, where the locking region can be sensed in a sensing region of at least one camera and an image-processing unit evaluates a signal of the camera to detect locking devices in a locking region of a movable object so as to detect locking devices efficiently and reliably.