Circuit arrangement for correcting digital signals

Claim 1

An electronic circuit arrangement for correcting the output signals of a photoelectric image transducer which includes a plurality of photoelectric transducer elements, said circuit arrangement comprising analog-to-digital converter means having an input operatively connected to said image transducer and a digital signal output, a plurality of selector switch means (13, 26, 27) including first, second, and third selector switch members each having an input terminal and two alternate output terminals, a like plurality of computer means (6, 7, 8) including first, second, and third circuits each having two inputs and an output, first, second and third memory circuit means (10, 11, 12) each having at least one input and an output, and electronic switching control means (5, 25) operatively connected to said circuit arrangement, said first selector switch member (13) being connected with its input terminal to said digital signal output (4) of said analog-to-digital converter means and with one of its outputs to one input of said first computing circuit (6), said first memory circuit means (10) being connected to the other output terminal of said first selector switch means and to the other input terminal of said first computing circuit which forms a first difference signal U i -U B , said second selector switch member (26) being connected with its input terminal to the output of said first computing circuit to receive said first difference signal with one of its output terminals to the second computing circuit (7) said second memory circuit means (11) being connected to the other output terminal of said second selector switch means and to the other input terminal of said second computing circuit which forms a second difference signal (U i -U B )-D i , said third selector switch member (27) being connected with its input to the output of said second computing circuit (7) with one of its output terminals to said third memory circuit means and with its other output terminal to said third computing circuit (17), said third memory circuit means (12) being connected with an output terminal (16) to said third computing circuit (17) which multiplies the second difference signal (U i -U B )-D i with a correction factor K i which is proportional to the slope of the characteristic curve of a respective photoelectric transducer element (3) to form real time corrected output signals U Ki for each image point signal U i of a photoelectric transducer element, wherein U B is a reference signal representative of a respective scanning period and wherein D i is a dark signal of the respective scanned photoelectric transducer element.