Abstract: A method and apparatus for filtering signals wherein a signal input to which the input signal is connected connects through a delay unit to a signal output and also connects through a filter branch to the signal output. The filter branch filters out constant parts and high-frequency parts of the input signal by the following steps. First the input signal is band-pass filtered. Thereafter, with a threshold filter, signal parts are eliminated having an amplitude below a prescribable threshold. In a following selector, signal amplitudes are allocated to a quantized, two-dimensional reference plane, and isolated signal parts are eliminated within the reference plane. Finally, a signal reconstruction is implemented by interpolation for coordinates of the reference plane at which a signal amplitude of a filtered signal part is essentially equal to zero.

Abstract: The drum for passing photographic paper along the surface of a heating trough is reversibly rotatable to maintain a high coefficient of friction between the exterior fibrous surface of the drum and the carrier undersurface of the paper. Drum rotation is reversed in the direction opposite to the transport of paper during periods between successive developments so as to brush the outer tips of the drum fibers against the surface of the trough, deflecting them in the direction of paper transport. The fiber surface of the drum may be set accordingly during manufacture by a grinding wheel rotated oppositely and concurrently with the drum to be finished, but at a much greater speed than the drum. The grinding wheel serves to incline the fiber tips so as to be initially directed in the direction of paper passage along the trough.

Abstract: A thermic developing station for recording material which is to be developed by means of heat, comprising a rotatable drum and a heating element which is adapted to fit the curvature of the drum surface, the recording material being fed through between the drum and the heating element by the drum and at the entrance of the recording material into the heating zone an unheated member is provided which is also adapted to fit the surface of the drum.