Abstract: A single-part, watertight wall covering device for dynamically displaying changing images on a wall surface on which the wall covering device is attached, includes a panel-type main body made of a transparent plastic having a front side and a rear side. At least one image generation element with a matrix-type pixel assembly is arranged on the rear side of the main body in such a way that an image generated by the image generation element/s is visible through the main body for an observer of the wall surface.

Abstract: The invention relates to a process for the optical testing of a surface of an object, particularly a compact disc, in which the surface is illuminated by at least one light source and the light reflected and/or scattered by the surface is projected onto at least one substantially flat, light-sensitive element of a light-sensitive receiver. The receiver consists of several pixels in the form of a grid in the line direction and the space direction. In a test phase at least one actual image is generated that is compared with at least one desired image which was produced in a read-in phase. To produce an image of the surface with more information the invention provides that during the read-in phase and/or the test phase at least two images of the surface are taken and the image of the surface which is projected on the light-sensitive element is displaced by at least a fraction of the dimension of a pixel in each case in at least one direction with respect to the light-sensitive element.

Abstract: A process and device for the optical testing of a surface in which the surface can be illuminated substantially from above by at least one upper light and from the side by at least one lower light, at a sharp angle with respect to the surface. The light reflected and/or scattered by the surface is recorded in a test period by at least one light-sensitive receiver and at least one actual image which is compared with at least one desired image is produced. To permit an improved test provision is made for the surface to be recorded by the light-sensitive receiver at least twice during the test period. During the recording periods in question the surface is illuminated by an at least intermittent illumination from above and/or from the side in a different manner in order to obtain at least two actual images with different illumination of the surface.