Abstract: The present invention concerns a process for the recreation of an analog luminance signal from a digital signal used for transmission after analog digital conversion of a luminance signal representative of a document to be transmitted, consisting in taking into consideration, before or after the D-A conversion of the reception, a number P of successive pixels P-2, P-1, P, P+1, p+2 and, as a function of their relative and absolute amplitudes, in processing the central pixel P, breaking it down into m sub-pixels having densities that are a function of those of the surrounding pixels. The present invention notably applies to the digital transmission of iconographic documents transmitted and received by a method of the "Belin" type.

Abstract: Method for the reconstitution, by filtering, of an analog signal, from a udo-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.