JPH0194768A - Video signal outline correcting device - Google Patents

Abstract

PURPOSE:To correctly execute the outline correction of a video signal by reducing the noise of the first video signal which is an input signal and switching an output signal based on the signal whose noise is reduced. CONSTITUTION:An input signal f(t+D) is inputted to a noise reducing circuit 11, noise-reduced, and when the output is assumed as fN(t+D), the output signal of a delay circuit 13 is expressed with fN(t-D). A subtracter 14 operates fN(t)-fN (t+D) at every time and an absolute circuit 16 outputs an absolute value X of the subtraction result. In the same way, a subtracter 15 operates fN(t)-fN(t+ D) and the circuit 16 outputs an absolute value Y of the subtraction result. Here, the sizes of the absolute values X and Y are compared by a comparator 18, a switching control signal to output f(t+D) by switching a changeover switch 9 to a terminal (a) in the period of X<Y, to output a signal f(t) by switching a terminal (b) when X=Y, and to output a signal f(t-D) by switching it to a terminal (c) in the period of X>Y is outputted, and the switch 9 is switched. As a result, a signal g(t) that an input signal f(t) whose rise time is slow is corrected into a signal waveform whose rise is quick is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal contour correction device for improving the sharpness, definition, etc. of video signals in color television receivers, video tape recorders, and the like.

[Conventional technology]

Figure 2 shows the configuration of a conventional device, where l is an input terminal into which a luminance signal is input, 2.3 is a delay circuit that delays the input signal by a certain amount of time, and 4 is an output signal of delay circuit 2 on the hourly side. A subtractor 5 calculates the amplitude difference between the output signal of the delay circuit 2 and the output signal of the delay circuit 3. A subtractor 6 outputs the absolute value A of the output of the subtractor 4. A value circuit, 7 is an absolute value circuit that outputs the absolute value B of the output of the subtracter 5, 8 is an absolute value circuit 6. Compares the magnitude of the outputs A and H of 7,
a comparator that outputs a switching control signal based on the result; 9;
is the input signal and delay circuit 2. based on this switching control signal.
This is a changeover switch that switches the output signal of No. 3 and outputs it to the output terminal IO.

Next, the operation will be explained. An input signal inputted from an input terminal 1 is delayed by a time in a delay circuit 2, and then delayed by a time in a delay circuit 3.

Therefore, the three input terminals a@b#C of the changeover switch 90 are simultaneously input with three signals: the input signal at the current time, and the input signal at the time 2D before.

Now, if the output signal of the delay circuit 2 is f(t), the current input signal is f(t+D), and the output signal of the delay circuit 3 is expressed as f(t-D). Figure 3 shows these three
This shows the positional relationship between the two signals. The subtracter 4 is on the hourly side (signal f
(t) amplitude) - (amplitude of signal f (10D)), (hereinafter written as f(t) - f(t+D)), and the absolute value circuit 6 calculates the subtraction result. Outputs the absolute value A.

Similarly, the subtractor 5 digits f(t)-f(t-D) are all calculated,
The absolute value circuit 7 outputs the absolute value B of the subtraction result. The comparator 8 compares the absolute values A and B, and during the period when A<H, the changeover switch 9 is switched to the terminal a and outputs the signal f(t+D), and when A=B, it is switched to the terminal S and the signal f is output. (t), and during the period of A>H, the terminal C is switched to the signal f (t
-D) is output, and the changeover switch 9 is changed over. As a result, the output terminal 10 outputs a signal g(t) shown by a thick solid line in FIG.

The waveform of this output signal g(t) is a signal that has been corrected to the signal waveform of the input signal f(t)e, which has a slow rise time, and has a fast rise time, and because it does not exceed the amplitude of the original signal, it causes the phenomenon of saturation. Never.

In addition, if the above-mentioned operation is expressed as a formula, A2If( の -f(t+DJl
... ...(1)13==I f(t) -f
(t-D) I...(2). Also, the output signal g (t) is expressed as.

[Problem that the invention seeks to solve]

In conventional contour correction devices, the switching control signal for switching the three signals as described above is created by calculation of the three signals to be switched, and if the S/N of the signal to be switched is poor, that is, the input signal If the signal contains a lot of noise, the switching control signal is likely to malfunction, causing problems such as the signal being switched at an undesirable point.

This invention was made in order to solve all of the above-mentioned problems.
An object of the present invention is to obtain a contour correction device for a video signal that can enhance the contour and improve the sharpness of an image.

[Means for solving problems]

A video signal contour correction device according to the present invention includes a circuit for reducing noise in a first video signal that is an input signal, and an amplitude difference between the noise-reduced signal and a signal that is incorrect at a certain time. a circuit that calculates the absolute value X of the amplitude difference between this delayed signal and a signal that is delayed for a certain period of time; The absolute values
When , the first video signal, when X=Y, the second signal,
A comparator is provided to control the changeover switch so as to output the third signal when X>Y.

[For production]

In this invention, a circuit for reducing noise in the first video signal is provided, so that the absolute values X and Y are compared correctly, and the changeover in the changeover switch is performed correctly.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 11
is a noise reduction circuit, so-called a noise reducer. 12.13 is a delay circuit that delays the noise-reduced signal by time; 14 is a subtracter on the hourly side that calculates the amplitude difference between the output signal of the delay circuit 12 and the input signal; 15 is the output of the delay circuit 12.13. 16 is an absolute value circuit that outputs the absolute value X of the output of the subtractor 14; 17 is an absolute value circuit that outputs the absolute value Yf of the output of the subtractor 15; 18 is an absolute value circuit that outputs the absolute value X.

This is a comparator that compares the magnitude of Y and outputs a switching signal based on the result. Based on this switching signal, the input signal and the output signal of the delay circuit 2.3 are switched by the switch circuit 9.

Next, the operation will be explained. The signal f (10D) input from the input terminal 1 is converted into the signal f via the delay circuit 2.3.
(t) and f(t-DJ), which are switched by the switch circuit 9 and an output signal g (t) is obtained at the output terminal 10. Such an operation is the same as the conventional one.

On the other hand, the input signal f(t+D) is input to the noise reduction circuit 11 and noise reduced, and if its output is fN (is 10D), then the output of the delay circuit 12 is fN(t), and the delay circuit 13 The output signal of is expressed as fN(t-D). The subtractor 14 calculates the hourly side fN(t)−fN(t+D),
The absolute value circuit 16 outputs the absolute value X of the subtraction result. Similarly, the subtractor 15 is fN(t) −fN(t −D)
The absolute value circuit 17 outputs the absolute value Y of the subtraction result. The comparator 18 compares the absolute values X and Y,
During the period of X<Y, switch the selector switch 9 to terminal & and use f(
t+D) is output, and when X=Y, the terminal is switched to output the signal f(t)t-, and during the period of X>Y, the terminal C is switched to output the signal f(t-D). is output, and the selector switch 9t is switched. As a result, a signal g(t)'f: obtained by correcting the input signal f(t) with a slow rise time to a signal waveform with a fast rise time is obtained.

Note that performance 31 in the above embodiment. Expressed in t-formula, X
Electricity 1 fN(t)-fN(t+D) I...
・(3) Y electric 1 fN(t) −fN(t −D) I
......(4). Also, the output signal g(t)
It is represented by .

Further, in the above embodiment, it is assumed that there is no time delay element in the noise reduction circuit 11, signal amplitude difference, absolute value 1 path 16, 17, comparison circuit 18, etc., and that the signal f(t+
D) and fN(t+D), f(t) and fN(t)
It is assumed that the pair of f(t-D) and fN(t-D) are signals at the same time. Further, in the above embodiment, the delay circuits 2, 3, 12, and 13 each having a delay time are used to generate three signal pairs (f(100)) delayed by the time.

f(t), f(t-Dn and fN(t+D), fN
(t), f*(t-D)), but three signal pairs may be created using a first delay circuit with a delay time of 2D and a second delay circuit with a delay time of 2D.

〔Effect of the invention〕

As described above, according to the present invention, the noise of the first video signal that is the input signal is reduced, and the changeover switch that changes the output signal is performed based on the noise-reduced signal. done accurately. Therefore, the contour correction of the video signal is performed accurately, and the sharpness and definition of the video signal are improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the apparatus of the present invention, and FIGS. 2 and 3 are block diagrams and operation explanation diagrams of the conventional apparatus. 1... Input terminal, 2, 3, 12. 13... Delay circuit, 9... Selector switch, 10... Output terminal, 11...
...Noise reduction circuit, 14.15...Subtractor, 16.
17... Absolute value circuit, 18... Comparator. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 3 Procedural amendment (voluntary) 6.7゜1, Indication of case Patent application No. 1982-252979 2,
Name of the invention Image signal contour correction device 3, person making the correction Representative Moriya Shiki 4, agent Contents of the correction The correction is made as shown in the attached sheet in Fig. 3. Catalog of attached documents 1 or more copies

Claims (1)

[Claims] (1) A circuit that creates a second signal that is delayed by a certain period of time with respect to the first video signal, a circuit that creates a third signal that is delayed by a certain period of time with respect to the second signal, and a circuit that creates a second signal that is delayed by a certain period of time with respect to the second signal; a changeover switch that switches and outputs the third signal, a circuit that reduces noise in the first video signal, and a circuit that creates a fifth signal that is delayed by a certain period of time with respect to the fourth signal whose noise has been reduced. and,
A circuit for creating a sixth signal delayed by a certain period of time with respect to the fifth signal, and an absolute value X of the amplitude difference between the fourth signal and the fifth signal.
A circuit that calculates the absolute value Y of the amplitude difference between the fifth signal and the sixth signal compares the absolute values X and Y,
The changeover switch is controlled so that the first video signal is selected during the period <Y, the second signal is selected when X=Y, and the third signal is selected and output during the period X>Y. A video signal contour correction device comprising a comparator that outputs a signal.