Abstract: Vertical lines in a distorted image, which are curved by distortion, are converted to straight vertical lines in a first image period. In a subsequent image period horizontal lines in the distorted image, which are curved by the distortion, are converted into straight lines. As the correction is effected in stages, it can be performed in a relatively fast manner, and a corrected image is available after one image period.

Abstract: A device comprising a transformer for step-wise varying voltages in which, in order to prevent undesired oscillations in the transformer, a circuit is included in the connection lead thereof, said circuit comprising at least one inductive element and at least one rectifying element. The inductance of the inductive element is a number of times higher than the leakage inductance of the transformer. The circuit has the property that the current through the inductive element (elements) does not change its direction when the sign of the voltage between its connection terminals is reversed.