Abstract: The sensor matrix (1) is mechanically shifted by a preset vector ({overscore (S)}) to remove sensor-resistant impurities relative to their reproducing effect in digital photography. From the comparison of image storage (data) before and after the mechanical shift (71, 72, 9) and from the thereby resulting comparison signal matrix (&Dgr;) it can be detected where sensor-fast impurities are present since through the mechanical shift there is also the image of the imaging beam (B1, B2) shifted but not the image of the impurities (xz, yz).

Abstract: The described device is part of a product theft prevention system and is used for deactivating resonance labels. It is intended for use in combination with a hand-held optoelectronic bar code reader (1), so as to permit the deactivation at the checkout of shops and stores of electronic resonance labels provided with a bar code and attached to products in a single operation and simultaneously with the determination of the bar-coded data. The deactivator has antennas (8, 9), which are located in a casing (11) fixable externally to the front end of the hand-held bar code reader (1) and which are constructed as ferrite antennas. As a result of the housing of the antennas (8, 9) and preferably all the high frequency-carrying parts (14, 15) of the deactivator in a separate casing (11), the deactivator can be used in combination with any random hand-held bar code reader, without any changes having to be made to the latter.