SU305599A1 - NONLINEAR CORRECTOR OF THE TLE OF THE TELEVISION (PHOTO-TELEGRAPHIC) PICTURE - Google Patents

Description

The invention is intended for use as part of the equipment of the transmitting part of broadcast and special black-and-white and color television systems, in high-quality television receivers, as well as in photo-telegraph systems.

Non-linear definition correctors are known, in which for reducing noise the degree of correction depends on the level of the video signal. In general, these nonlinear correctors consist of a video signal amplitude analysis circuit, a correction signal generation circuit, and a correction signal mixer with a full video signal.

The aim of the invention is to improve the quality of the correction.

To do this, in the proposed nonlinear corrector of clarity, the outputs of the phase-split amplifier of the correction signal generator are connected directly and through delay lines to the coincidence circuits, the signals from which are fed to the input of the limiter to the maximum.

The drawing shows the block diagram of the proposed clearness corrector.

The clarity corrector contains a video signal analysis circuit consisting of two pulse selectors by duration (elements / -7), pulse amplitude modulator 8, high-pass filter 9, delay line 10

for a full video signal, mix //. Pulse selectors by duration provide for the selection of two-pole video pulses of minimum duration corresponding to

the transmission of single-element (in the horizontal direction) parts on dark and light backgrounds. The duration selectors are made in the form of differentiating / and inverse 2 amplifiers, delay delays 3 and 4, coincidence circuits 5 and 6, and limiter maximum 7. The input of the clarifier is a BIJ signal taken from a preliminary or intermediate amplifier of the television path. Video signal from device input

enters the video signal analysis circuit and the delay line 10. In the analysis circuit, the signal is differentiated, and the resulting bipolar pulses, corresponding to the leading and trailing edges of the source signal, are sent to the inverse amplifier 2. At the output of the latter, two signals of opposite polarity are produced the operation of the circuits coinciding with 5 and 6. The delay lines 3 and 4, the input of which receives signals from the output of the amplifier 2, ensure the coincidence of the moments of the passage of the impulses of the front (delayed) and rear (non-retained) ph Ronts of the original video signal. Obviously, with the impulse time in the video signal, the output at the output of the 5n 6 connection schemes is observed only for the video impulses that correspond to the transmission of single-element details of the image.

Two delay lines and two coincidence circuits provide for the selection of pulses of minimum duration of positive and negative polarity (a light detail on a dark background and a dark detail on a light background).

To obtain pulses with a constant amplitude, the signal from the output of the coincidence circuits is fed to the limiter to a maximum of 7.

So, on the output of the video signal apalysis circuit, only impulses are generated and if the video signal has minimum pulse durations, i.e., when transmitting single element picture details.

The generated pulses from the output of the limiter arrive at the amplitude-pulse modulator 8, the input of which receives the full video signal from the delay line 10 and the high-pass filter 9. The delay line ensures that the input pulse of the analysis circuit and video pulses coincide at the modulator input. singleton parts in a full video signal.

The high pass filter eliminates the effect of the low frequency components of the full video signal on the amplitude of the pulses at the output of the amplitude modulator. As a result, the pulse amplitude on the modulator 8 output will be uniquely determined only by the magnitude of the video pulses of the single-element components in the full video signal.

The output of the modulator is a correction signal and using a mixer 11

is added to the full video signal, thereby increasing the amplitude of the video pulses of single-element parts. The magnitude of the amplitude increase is established from 1 point of view of the half-restored: 1 time amplitude of fine detail pulses, i.e., to the full restoration of clarity.

The possibility of a relatively simple practical implementation of the proposed device is based on the low required accuracy of restoring the true amplitude and duration of the video pulses of single element parts. The latter is based on the fact that the required accuracy is determined by the contrast sensitivity of the eye, the magnitude of which, when perceived by small details of reproduction, is low and lies in the range of 0.2-1.5 (While it is 0.02-0% of large details), 05).

Subject invention

A nonlinear clarity corrector of a telezioin (photo-telegraph) image containing a mixer to which a video signal and a signal from an amplitude modulator feed through a delay line, and a correction signal generator connected via a limiter to a maximum to the input of an amplitude modulator to which A high-frequency filter is supplied with a delayed video signal, characterized in that, in order to improve the quality of the correction, the outputs of the phase split amplifier of the correction signal generator are connected directly and through the delay lines to the coincidence circuits, the signals from which are fed to the input of the above limiter to the maximum.