Correction system for video signals having a limited amplitude range
OwnerGerhard Illetschko, Horst Pethinventors
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Abstract
The video signals are applied to a standard aperture correction circuit and also to a non-linear circuit. The output of the non-linear circuit and the output of the standard aperture correction circuit are applied to the two inputs of a modulator whose output is combined in a summing circuit with video signals delayed by a time delay corresponding to the time delay in the non-linear circuit and modulator. In a preferred embodiment the non-linear transfer function corresponds to A.sup.2 -A and is achieved by a double-balanced modulator the DC level at whose inputs is adjusted to yield the desired transfer function.
Claims7
In an aperture correction system including aperture correction means having an input for receiving video signals and an output for furnishing aperture correction signals varying as a function of said video signals, an additional correction system comprising, in combination, non-linear circuit means having an input for receiving said video signals, a non-linear transfer characteristic, and an output, for furnishing a modified video signal varying as a function of said video signals and said non-linear transfer characteristic at said output;
- modulator means having a first input connected to said output of said aperture correction means, a second input connected to said output of said non-linear circuit means and a modulator output, for furnishing a modulator signal corresponding to signals applied at said first and second inputs at said modulator output;
- and summing circuit means having a first input for receiving said video signals, a second input connected to said modulator output, and a summing output, for furnishing corrected video signals corresponding to the sum of the signals at said first and second inputs at said summing output.
Dependencies are inferred from the claim text.