Abstract: A device and a process, for measuring deformations of an elastically deformable object, provides at least one optically detectable mark at a longitudinal position along the one elastically deformable object, as well as at least one camera with a matrix of photosensitive elements. The camera is directed towards the at least one optically detectable mark such that this is imaged on the matrix of photosensitive elements. The image data of the camera are sent to an image processing device, which is set up to determine the position of the mark on the matrix of photosensitive elements on the basis of an image recognition. A deviation of the position of the optically detectable mark from the at least one set point is determined and quantified by a computing device.

Abstract: A method and system are provided for determining points of disturbances in a fibrous planar structure. The planar structure is conveyed past a receiver having an array of photodiodes. The photodiodes determine the brightness of the planar structure and compares the received brightness value to threshold values. Brightness values in excess of a predetermined threshold value are deemed to be disturbances in the fibrous planar surface.