A video signal processing circuit, particularly for use in conjunction with a single-tube indexing color television camera, provides an output video signal to which a vertical aperture correction has been added, and which cancels undesired line-to-line amplitude changes, thereby preventing line-crawling distortion. The video signal processing circuit includes an input circuit to which an input video signal is supplied, a delay circuit for delaying the input video signal from the input circuit by one horizontal scanning interval, a signal squaring circuit for squaring the difference in level between the input video signal and the delayed input video signal, and a mixing circuit for combining the input video signal with the squared signal output from the squaring circuit. The squaring circuit can include a multiplier circuit, or a square-law characteristic FET, to which the difference in level between the delayed and undelayed input video signals is applied. Alternatively, the squaring circuit may include a multiplier FET to which the delayed and undelayed input video signals can be directly applied.
A television pick-up arrangement comprising a solid-state picture pick-up device rows of picture pick-up elements of which are connectable to parallel inputs of two output shift registers. When the shift registers are read simultaneously they supply at their series outputs picture signal which are associated with each time two pairs of rows of picture pick-up elements. According to the invention, the two picture signals are applied on the one hand separately to a vertical aperture correction circuit having only one delay device with a time delay of one line period and on the other hand combined to a horizontal aperture correction circuit, the corrected signals being combined behind said correction circuits. Advantageous use can then be made of a device in which pick-up information is obtained by both holes and electrons which are caused by photons.
A timebase error compensation apparatus is provided in a video tape recorder having a plurality of rotary reproducing heads from which signals are sequentially switched over to obtain a continuous reproduced video signal. The apparatus comprises a compensation circuit for compensating a timebase error included in the reproduced video signal; a detection circuit for detecting a horizontal scan line period during which the signal from one rotary reproducing head is switched over to the signal from another rotary reproducing head to generate a mask control signal; and a replacement circuit responsive to the mask control signal for replacing the reproduced video signal of the horizontal scan line period with the reproduced video signal of a horizontal scan line period adjoining to the horizontal scan line period.
Signal components of the luminance signal are delayed by a 90.degree. phase by a first filter and pass therethrough, where the closer the frequencies of the signal components to the upper limit frequency of the frequency bandwidth of the luminance signal, the less the signal components attenuated. The signal components also pass through a second filter, where the phase of the signal components do not change, the closer the frequencies of the signal components to the upper limit frequency of the frequency bandwidth, the less the signal components attenuated. The signal components that have a phase difference of 90.degree. with respect to each other and that pass through each of the filters undergo vector composition to generate a signal that has an amplitude which is the root of the sum of the squares of the two amplitudes. A signal that has the same phase as the signal component that passes through the second filter and that has the same amplitude as the amplitude of the signal subjected to the vector composition is then generated. From this signal the signal component that passes through the second filter is subtracted to generate the edge emphasis component. This edge emphasis component is added to the luminance signal to emphasize the edge of an image.
