JPH027226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a device for suppressing flicker components caused by an illumination light source included in a television video signal.

(Description of Prior Art) In regions where the commercial power supply frequency and the number of fields on the screen are different, when a subject illuminated by fluorescent lamps, mercury lamps, etc. is photographed and played back with a television camera, flickering caused by the illumination appears on the screen. ) occurs.

Focus is placed on a specific part of the photocathode of the image pickup tube that corresponds to an arbitrary point on the screen.

It can be considered that the signal output from that part is proportional to the amount of light incident on that part in 1/30 second. It is known that the frequency of the light source as described above is twice the frequency of the power source.

The number of light source peaks included in 1/30 seconds is (1/3
0)/(1/100), which is not an integer, and the amount of light from the light source that enters that area in 1/30 seconds always fluctuates, which causes flicker.

Since the flicker often impairs the quality of the screen and causes discomfort, various countermeasures have been proposed and implemented.

The first countermeasure is to replace the light source that causes the flicker with an incandescent lamp with less ripple, or to install more incandescent lamps to reduce the ripple of the light source. Although this measure is effective, there are many environments in which such a measure cannot be taken. When broadcasting live sports at night using illumination such as mercury lamps, it is virtually impossible to use incandescent lamps with less ripple than the mercury lamps.

As a second measure, the inventor of the present invention constantly detects the waveform of the light source using a silicon photodiode or the like.
We have studied a method of superimposing the output on a video signal so as to cancel out the flicker, and have obtained good results.

However, this method can only be implemented at the imaging site, and is powerless when playing back a videotape that already contains such flicker components. Further, some problems remain with the second measure, such as the need to arrange a light source variation detection means such as the silicon photodiode in addition to the television camera at the imaging site, which is cumbersome.

(Description of the purpose of the invention) The purpose of the present invention is to solve all of the above-mentioned problems, and to suppress the flicker components contained in television video signals, which can be used not only at the imaging site but also when playing back recorded media. The objective is to provide a device that

(Structure and operation of the invention) The present invention was made based on the discovery of the following principle.

The video signal including the above-described flicker component is similar to a video signal obtained by imaging a subject illuminated with a non-pulsating light source and modulated with the frequency of the flicker component.

Therefore, if a video signal containing a flicker component is modulated with a signal having the opposite phase and the same amplitude as the flicker component, a flicker-free video signal that is almost the same as a video signal obtained by imaging a subject illuminated with a non-pulsating light source can be obtained. It should be possible.

The following examples correspond to the present invention.

A device for suppressing a flicker component included in a television video signal according to the present invention extracts a frequency component from a television video signal that includes a flicker component having a frequency twice that of the illumination power source that illuminates the object to be imaged. sampling signal and timing signal forming means 4, 5, 8a for forming a sampling signal and a timing signal; an amplitude modulation section 3 for amplitude modulating the television video signal;
a sampling section 8 that samples the residual flicker component of the output of the amplitude modulation section 3 using the sampling signal and generates a signal corresponding to the direction and level of modulation corresponding to the residual flicker component;
It is comprised of a flicker suppression signal generating section 6 which outputs an inverse modulation signal in a direction in which the residual flicker component decreases at the same frequency as the flicker component to the amplitude modulation section from the timing signal and the signal from the sampling section.

(Description of Examples) The present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a block diagram showing an embodiment of a circuit of a device for suppressing flicker components contained in a television video signal according to the present invention.

A television video signal (hereinafter simply referred to as a flicker video signal) that may contain the above-mentioned flicker component is connected to the video signal input terminal 1. This signal source may be the output signal of a television camera, as described above, or the output of a videotape.

The television video signal is branched to an amplitude modulation section 3 and a flicker component detection section 4.

The clamp circuit 3a of the amplitude modulation section 3 is located at the pedestal level position of the video signal (flicker component is zero).
This is a circuit that clamps the video signal based on .

The modulation circuit 3b is a blanking gate 3 which will be described later.
This is a circuit that amplitude-modulates a flicker video signal using a modulation signal supplied via e.

The synchronization separation circuit 3c is a circuit that separates a synchronization signal from a flicker video signal.

The blanking signal generation circuit 3d generates a blanking pulse corresponding to the blanking period of the television video signal in synchronization with the output of the sync separation circuit 3c. The blanking gate 3e closes the gate during the generation period of the blanking pulse to prevent modulation during that period. The fritzker component detection unit 4 is
A 100Hz bandpass filter 4a from the Fritzker video signal and a Schmitt circuit 4 that shapes the 100Hz waveform extracted by the bandpass filter 4a.
It is formed from b. The signal corresponding to the flicker component extracted by the 100 Hz bandpass filter 4a is shaped by the Schmitt circuit 4b and connected to the timing adjustment section 5.

The timing adjustment section 5 is provided with a delay circuit 5a and a delay circuit 5b in parallel.

The signal _P1 delayed and timing-adjusted by the delay circuit 5a is supplied to a flicker suppression signal generator 6,
Used as a suppression signal clock.

The signal _P2 delayed and timing-adjusted by the delay circuit 5b is supplied to the sampling section 8, and is used to generate a sampling pulse Ps for detecting the flicker component remaining after modulation.

The output terminal of the amplitude modulation section 3 is connected to the input terminal of a residual flicker component detection section 7 consisting of a 100 Hz band pass filter. The output of the residual flicker component detection section 7 is connected to the sampling gate 8b of the sampling section 8.

A sampling pulse generating circuit 8a of the sampling section 8 generates a pulse Ps for sampling the maximum part of the output (100 Hz sine wave) of the flicker component detecting section ₇ based on the signal P2. In other words, the timing of the signal _P2 is adjusted by the delay circuit 5b so that it coincides with a certain phase region where the residual flicker component is maximum.

The signal es sampled by the sampling pulse Ps is amplified by a DC amplifier 8c.

An extremely low reference voltage (Vref) is connected to the DC amplifier 8c.

The output voltage Ef of the DC amplifier 8c is supplied to the switching circuit 6b of the flicker suppression signal generator 6 as a DC voltage signal Ef that increases or decreases in accordance with the remaining flicker component.

The switching circuit 6b of the flicker suppression signal generating section 6 switches the DC voltage signal Ef proportional to the residual flicker component with the signal _P1 delayed and timing-adjusted by the delay circuit 5a, converting it into a rectangular wave _Ef1 , The signal is supplied to a 100Hz bandpass filter 6a. The bandpass filter 6a receives the rectangular wave Ef ₁
Convert it to a sine wave ef and connect it to the blanking gate.

The sine wave ef is connected as a modulation signal to the modulation circuit 3b via the blanking gate 3e.

Thereby, the modulation circuit 3b modulates the flicker video signal so as to suppress the flicker component in the flicker video signal.

Various modifications can be made to the embodiments described in detail above within the scope of the present invention.

Of course, it is also possible to form a modulation signal based on the level of the flicker component detected at the video signal input terminal.

(Description of Effects of the Invention) As a result of experiments using the above-mentioned device in an outdoor baseball broadcast illuminated with mercury, etc., the inventors of the present invention found that
It was confirmed that the screen quality could be improved to such an extent that flicker caused by the light source could no longer be observed.

It was also confirmed that when reproducing a flickering video signal from an already recorded videotape, the screen quality could be improved to such an extent that flickering caused by the light source could not be observed.

That is, according to the present invention, flicker components contained in a television video signal can be suppressed by obtaining information from the television video signal.

Further, the present invention can be easily implemented by adding the above-mentioned simple circuit without modifying existing equipment in any way.

Since the circuit has a simple configuration and can be manufactured at a very low cost, it can be applied not only to the field of broadcasting but also to amateur home video.

Conventionally, as mentioned above, when broadcasting indoor competitions, etc., it was necessary to install additional lighting using incandescent lamps or the light source fluctuation detection means proposed earlier, which was cumbersome. If it is built into the side, such consideration is not necessary.

When the light from the incandescent lamps used to suppress Fritzker in indoor competitions etc. directly entered the eyes of the competitors, it often interfered with the competition. With the device according to the invention, no additional illumination by incandescent lamps is required.

Since fritzing can be removed during playback even from already recorded fritzing video signals, reporters no longer need to consider the light source, making reporting easier.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a circuit of a device for suppressing flicker components contained in a television video signal according to the present invention. 1...Video signal input terminal, 2...Processed signal output terminal, 3...Amplitude modulation section, 3a...Clamp circuit, 3b...Modulation circuit, 3c...Synchronization separation circuit, 3d...Blanking signal generation Circuit, 3e...
... Blanking gate circuit, 4 ... Flicker component detection section, 4a ... Bandpass filter, 4b ... Schmitt circuit, 5 ... Timing adjustment section, 5a ...
...Delay circuit, 5b...Delay circuit, 6...Flicker suppression signal generator, 6a...Band pass filter, 6
b...Switching gate circuit, 7...Flicker component detection section, 7a...Band filter, 8...Sampling section, 8a...Sampling pulse generation circuit, 8b...Sampling circuit, 8c...DC amplifier circuit .

Claims (1)

[Claims] 1. Sampling signal and timing signal forming means for extracting a frequency component from a television video signal containing a flicker component having twice the frequency of the illumination power supply that illuminates the imaging target and forming a sampling signal and a timing signal; an amplitude modulation unit that amplitude modulates the television video signal; and a residual flicker component of the output of the amplitude modulation unit is sampled by the sampling signal to generate a signal corresponding to a modulation direction and level corresponding to the residual flicker component. a sampling section;
and a flicker suppression signal generation section that outputs, from the timing signal and the signal from the sampling section, an inversely modulated signal having the same frequency as the flicker component and in a direction in which the residual flicker component is reduced to the amplitude modulation section. A device that suppresses Fritzker components contained in.