method for restoring by filtering an analog signal based on a pseudoanalogen signal obtained by a dual analog / digital, digital / analog signal analogumsetzung referred to any treatment of the digital signal.

摘要

Method for the reconstitution, by filtering, of an analog signal, from a pseudo-analog signal obtained by a double, analog to digital, digital to analog conversions of the analog signal, with processing of the digital signal. In greater detail, the pseudo-analog signal, obtained by double analog to digital, digital to analog conversion of an analog signal, is applied to an active filter the impedance of which is controlled by the absolute derivative of the positive value of the pseudo-analog signal. The derivative is obtained by a circuit comprising an RC filter receiving the pseudo-analog signal and a memory controlling the value of the impedance of the filter. The invention has particular application to the restitution of graphic or iconographic documents which have been previously digitally encoded.