an optoelectronic apparatus is provided for identifying marks comprised of defined contrast patterns , particularly barcode symbols . the device includes a transmitting element which emits transmitted light and a receiving element . the transmitted light is guided across the marks , and the received light reflected by the marks has an amplitude modulation imposed by the contrast of the marks , with the received light being converted into a voltage signal that forms the received signal in the receiving element . the voltage signal is converted into a binary signal and filtered by an arrangement of digital filters for compensation component stipulated distortions prior to being fed to a threshold - value unit for evaluation of the contrast pattern .