JPS5820503B2 - Contour compensation signal discrimination method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining whether a contour compensation signal is included in a television video signal transmitted from a TV camera or a TV station.

In order to improve the clarity of a television image, contour compensation processing is often performed on horizontal and vertical components using a contour compensation circuit mainly consisting of a differential circuit.

However, for example, when a video signal is sent from the main station of a television station to a branch office, if the signal that has already been subjected to contour compensation processing at the main station is subjected to further contour compensation processing at the branch station, a ghost-like image will result, which will actually deteriorate the image quality. do.

Therefore, it is necessary to determine whether contour compensation processing has been performed on the video signal.

Conventionally, such judgments have been made by TV station operators who monitor images with their naked eyes and process them, but of course there are individual differences, and this requires constant attention, which is extremely troublesome.

Therefore, there is a need for an apparatus that determines whether or not contour compensation processing has already been performed on a video signal, and automatically performs contour compensation processing if it has not been performed.

An object of the present invention is to provide a contour compensation signal discrimination method for determining the presence or absence of a contour compensation signal in a video signal using an electric circuit, in response to the above-mentioned demands. The content is to calculate the difference between the television video signal and a signal delayed by one horizontal scanning period, and within a certain period of this obtained signal, A contour compensation signal is generated in the television video signal by detecting whether a predetermined number or more of pulse pairs consisting of a pair of positive, negative, or negative, positive polarity pulses whose phases are shifted by a scanning period are present. It is characterized in that it determines whether or not it is included and outputs a determination signal.

The present invention will be explained in detail based on illustrated embodiments.

Contour compensation processing is usually performed on both horizontal and vertical components, or because the horizontal scanning period is extremely short and signal processing is somewhat difficult, contour compensation processing is performed using vertical video signals. Determine presence/absence.

Figure 1 (1) shows a video signal that does not include a contour compensation signal, and Figure 1 (2) shows a video signal that has been subjected to contour compensation processing using the commonly used second-order differential format. By emphasizing the signal in the shaded area, the outline becomes clearer.

Note that H represents the horizontal scanning period.

The method according to the present invention is carried out by, for example, the discrimination circuit shown in FIGS. 2 and 3, and the signal a shown in FIG. 4, which has been subjected to contour compensation processing, is input from the input terminal IN in FIG. 2. .

The signal a is branched, one is input to a delay line circuit 1 that continuously delays one horizontal scanning period, the delayed signal is input to a subtraction circuit 2, and the other video signal a is directly input to a subtraction circuit. Enter 2.

These signals a and b are converted into production signals in a subtraction circuit 2, and furthermore, high frequency components are removed in a low-frequency offshore wave circuit 3, resulting in signal C in FIG.

What should be noted here is that in the video signal to which the contour compensation signal is added, in signal C, one horizontal scanning period (IH)
This results in pulse pairs consisting of pulses with positive, negative or negative, positive polarity that are out of phase by .

It is clear that in the video signal shown in FIG. 1(1) which has not been subjected to contour compensation processing, no pulse pair is obtained even if signal C is obtained.

This signal C is sent to a determining circuit 4 to determine whether or not a predetermined number of pulse pairs exist within a certain rule, or the so-called frequency thereof, to determine whether contour compensation processing is to be performed.

The reason why the discrimination is based on the occurrence rate of pulse pairs is because, as will be described later, pulse pairs may be distorted by accidental noise signals, and there is a risk that they may be mistaken for contour compensation signals. .

The signal C obtained by the subtraction circuit 2 and the like is input to the input terminal T of a T flip-flop circuit (hereinafter referred to as an FF circuit) 41 in the determination circuit 4 shown in FIG.
and the horizontal blanking signal e input to the clear end CL of the TFF circuit 41, the signal up to the leading edge of the horizontal blanking signal e corresponding to the positive polarity component of the signal C becomes TF.
It is output from the set output terminal Q of the F circuit 41 as a signal d.

This signal d is input to the input end of the DFF circuit 42, and the horizontal blanking signal e that has passed through the NOT circuit 43 is input to the DF circuit 42.
By inputting it to the input terminal T of the F circuit 42, the next IH pulse signal f is output from the reset output terminal Q of the DFF circuit 42.

The signal f is input to a NOR circuit 44 together with a horizontal flanking signal of opposite polarity, and a signal g obtained by removing the blanking period of the signal e is output from the NOR circuit 44.

This output signal g is input to the clear terminal CL of the TFF circuit 45, and the opposite polarity signal C of the signal C which has passed through the NOT circuit 46 is input to the input terminal T of the TFF circuit 45, and the set output terminal Q of the TFF circuit 45 A signal for determining the presence or absence of a negative polarity component in the signal C is obtained.

This signal is a signal obtained by detecting a pulse pair consisting of a positive pulse and a negative pulse.

The signal is input to the counting circuit 47, and when it reaches a preset value set in advance, it is input to the monostable multi-bi break circuit 48.
A signal is sent to the output terminal OUT, and a discrimination signal is output from there to the output terminal OUT.

However, the signal l is a reset signal of the counting circuit 47,
For example, a vertical blanking signal is used, in which case the preset value of the counting circuit 47 is preferably about 10 to 30.

Note that the C
The R circuit is for delaying the output determination signal from the circuit 48.

It goes without saying that the method of the present invention is also effective for contour compensation signals in the first-order differential format, which can be obtained relatively easily.

The video signal a in the first-order differential format is as shown in FIG. 5, and is distinctive in that there is no dark area before the highlight area.

It is clear that a pair of pulses can be obtained from the signal C in this case as well, and the presence or absence of a contour compensation signal can be detected in the same way as in the case of the second-order differential type.

Further, as mentioned above, even if an accidental pulse appears in the video signal a as shown in FIG. 6, a pair of pulses will occur in the signal C, but the probability is extremely small. Since the counting circuit 46 prevents the error from becoming a signal indicating that the contour compensation signal is present, this does not pose a problem.

In this way, when a signal is output from the determination circuit 4 to OUT, this video signal contains a contour compensation signal, so whether it is necessary to pass the contour compensation circuit or whether the signal from the determination circuit 4 is If not, the video signal may be passed through the contour compensation circuit in the next vertical scanning period.

Various circuits other than the embodiments can be used as the circuits used to carry out the method of the present invention.

In particular, it is fully conceivable that the configuration of the determination circuit 4 may be based on another logic circuit.

As explained above, the contour compensation signal discrimination method according to the present invention is a method of determining the presence or absence of contour compensation processing by fully identifying the presence of pulse pairs consisting of positive and negative pulses at a certain frequency or more in a video signal. If the input gate of the contour compensation circuit is operated using this discrimination signal, contour compensation will be automatically performed on all images, and an image with stable image quality will be obtained.

[Brief explanation of drawings]

FIG. 1 shows a time chart of a video signal without contour compensation, 2 shows a time chart of a video signal with contour compensation, FIG. The figure is a block circuit diagram showing a circuit configuration for implementing the present invention, FIG. 3 is a logic circuit diagram of a determination circuit, and FIG.
FIG. 5 and FIG. 6 are explanatory diagrams using time charts for explaining the determination method. 1 is a delay line circuit, 2 is a subtraction circuit, 3 is a low-frequency wave transducer,
4 is a determination circuit.

Claims (1)

[Claims] 1 Find the difference between a television video signal and a signal delayed by one horizontal scanning period, and within a certain period of this obtained signal, a pair of positive and negative signals whose phase is shifted by one horizontal scanning period are calculated. Or by detecting whether a predetermined number or more of pulse pairs consisting of pulses having negative and positive polarities exist.
A method for determining a contour compensation signal, comprising determining whether or not a contour compensation signal is included in the television video signal and outputting a determination signal.