JPH01174090A - Video signal separator - Google Patents

Abstract

PURPOSE:To attain more accurate Y/C separation almost without increasing the memory capacity by storing correlation information between the original signal and the selected signal in case of Y/C separation to a digitized video signal and using the information later. CONSTITUTION:A video signal converted into a digital signal by an A/D converter 1 is subjected to chrominance signal component extraction by a BPF 2 and the result is given to a delay circuit 3. The output of the delay circuit 3 is subtracted from the output of the BPF 2 by a subtractor 7 and the result is halved by a multiplier 8 into a comb-line filter component. Moreover, the output of the BPF 2 and the output of the delay circuit 3 are added by an adder 4, resulting in being a correlation output signal, it is converted into two kinds of correlation information sets (with correlation and without correlation), inputted to a delay circuit 6, where the signal is retarded. The output of the conversion circuit 5 and the output of the delay circuit 6 are inputted to a selection circuit 9, where a comb-line filter output or a simple BPF output is decided to be outputted as a color signal output.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a device for separating luminance signals and color signals (hereinafter abbreviated as Y/C separation) used in video tape recorders and the like.

Conventional technology In recent years, there has been an increasing demand for high image quality for consumer video tape recorders. The importance of Y/C separation devices that separate Y/C signals is increasing. Comb filters are used for Y/C separation, but dot interference and cross colors may become more noticeable, and By looking at the correlation, it is necessary to judge whether to use a comb-shaped filter or a simple band-pass filter.

Hereinafter, an example of the above-mentioned conventional Y/C separation device will be described with reference to the drawings.

FIG. 2 shows a conventional Y/C separation device. In FIG. 2, 12 is a band pass filter that passes the color signal band. 13 is a delay circuit. The length of the delay circuit is IH for NTSC signals and 2H for PAL signals. 14 is an arithmetic circuit and an addition circuit. 15 is a selection circuit. 16 is a subtraction circuit.

17 is a circuit for multiplying by 1/2. 18 is a switching circuit. 19 is a subtraction circuit.

The operation of the Y/C separation device configured as described above will be explained below using FIG. 2.

The video signal is separated into color signal band components by the BPF 12, and a first color signal is output. The first color signal is delayed by a delay circuit 13. The first color signal and the first color signal that has passed through the delay circuit 13 are added in an addition circuit 14, and the first color signal that has passed through the delay circuit 13 is added in a subtraction circuit 16. The color signal is subtracted, and the value is halved by the multiplier circuit 17. The output of the multiplication circuit 17 becomes the color signal (square filter output). The output of the addition circuit 14 is input to the selection circuit 15, and if the value is smaller than a certain value, the first color signal and the delay circuit 1 are inputted.
It is determined that there is a correlation with the color signal output from 3, and the switching circuit 1
The output of 8 becomes the output of the multiplication circuit 17, which becomes the color signal output. If the value input to the selection circuit 15 is larger than a certain value, it is determined that there is no correlation between the two color signals, and the switching circuit 18 outputs the first color signal, which is the color signal. The signal output will be higher. A subtraction circuit 19 subtracts the color signal from the video signal to produce a luminance signal output.

Problems to be Solved by the Invention However, in the above configuration, there is a problem in that the high-frequency vertical line component of Y becomes a color signal, resulting in a cross color. Furthermore, if the length of the delay circuit is doubled, a variety of correlation information can be obtained, but this increases the cost. A similar problem occurs even when Y/C separation is digitally processed.

In view of the above problems, the present invention provides a Y/C separation device that can perform more accurate Y/C separation without increasing the memory.

Means for Solving the Problems In order to solve the above problems, the present invention provides a Y/C separation device that includes an A/D converter that converts a video signal into a digital signal;
A BPF that passes the color signal band from the video signal converted into a digital signal by the A/D converter, and a first delay circuit that delays the first color signal output from the BPF.
The length of IH for NTSC signals and 2H for PAL signals), the first color signal, and the first color signal output from the first delay circuit are calculated. a first arithmetic circuit that calculates the correlation of the first arithmetic circuit; a conversion circuit that converts the result output from the first arithmetic circuit into a certain type of correlation value; and a conversion circuit that delays the correlation value output from the conversion circuit. Second delay circuit (11 for NTSC signals)
- (2H length in the case of a PAL signal) and a second arithmetic circuit that takes the difference between the first color signal and the first color signal output from the first delay circuit and halves the difference. a switching circuit that outputs either the second color signal output from the second arithmetic circuit or the first color signal; and the correlation value
A selection circuit that determines the correlation value from the correlation value output from the second delay circuit, and a signal output from the switching circuit as a third color signal, and the third color signal is subtracted from the video signal. is used as a luminance signal output, and the third color signal is used as a color signal output.

Operation According to the present invention, a video signal is converted into a digital signal by an A/D converter using the above-described configuration.

The video signal converted into a digital signal passes through a BPF that passes the color signal band, and a first color signal is output. The first color signal is input to a first delay circuit, the first color signal and the first color signal output from the first delay circuit are input to a first arithmetic circuit, A sum is calculated and the output of the first arithmetic circuit is input to a conversion circuit that converts it into a certain type of correlation value. Further, the output from the conversion circuit is delayed by a second delay circuit. Based on the output of the conversion circuit and the output of the conversion circuit output from the second delay circuit, it is determined whether to output a rectangular filter or a simple BPF as a color signal output. is obtained by subtracting the output color signal from the original video signal.

Example Below, regarding a Y/C separation device which is an example of the present invention,
This will be explained with reference to the drawings. FIG. 1 shows a Y/C separation device in an embodiment of the present invention.

In FIG. 1, 1 is an A/D converter, 2 is a BPF, 3 is a first delay circuit, 4 is an adder, 5 is a conversion circuit, and 6
is the second delay circuit, 7 is the subtracter, 8 is the multiplier, 9
10 is a selection circuit, 10 is a switching circuit, and 11 is a subtracter.

The operation of the Y/C separation device configured as described above will be explained below with reference to FIG.

The video signal is converted into a digital signal by an A/D converter 1. The video signal converted into a digital signal passes through the BPF 2 and color signal components are extracted. The output of BPF2 is
The signal is input to the first delay circuit 3. From the output of BPF2,
The output of the first delay circuit 3 is subtracted by a subtracter 7,
The multiplier 8 divides the signal into 1/2, resulting in a comb filter component. Further, the output of the BPF 2 and the output of the first delay circuit 3 are added by an adder 4 to obtain a correlation output signal. The output of the adder 4 is converted by the conversion circuit 5 into two types of correlation information (correlated and non-correlated). Conversion circuit 5
The output is input to the second delay circuit 6 and delayed.

The output of the conversion circuit 5 and the output of the second delay circuit 6 are input to a selection circuit 9, which determines whether to output a comb filter output or a simple BPF output as a color signal output. do. If the output of the conversion circuit 5 is correlated, it is determined that the output of the BPF 2 and the output of the first delay circuit are correlated, and the output of the multiplier 8, that is, the output of the rectangular filter is set as the color signal output. .Furthermore, when the output of the conversion circuit 5 has no correlation and the output of the second delay circuit has no correlation, it is determined that there is a high frequency component of Y, and the comb filter output is used as the color signal output. , when the output of the conversion circuit 5 is uncorrelated and the output of the second delay circuit is correlated, the output of the BPF 2 and,
It is determined that the output of the first delay circuit has no correlation, and the BPF
Let the output of 2 be the color signal output. The luminance signal is obtained by subtracting the color signal from the video signal using a subtracter 11.

As described above, according to this embodiment, when performing Y/C5tm on an A/D-converted and digitized video signal, correlation information between the original signal and the delayed signal is stored. ,
By using that information later, the presence or absence of correlation can be detected more accurately, and the amount of memory increases little.

Effects of the Invention As described above, according to the present invention, only the correlation information between the original signal and the delayed signal is extracted and delayed, so that the amount of memory for delaying is small, and It is possible to obtain an excellent effect of realizing a Y/C separation device with more accurate Y/C separation accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a Y/C separation device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional Y/C separation device. 1...A/D converter, 2...BPF,
3...First delay circuit, 4...Adder, 5...Conversion circuit, 6...Second delay circuit, 7... ...subtractor, 8...multiplier,
9...Selection circuit, 10...Switching circuit,
11... Subtraction circuit, 12... BPF,
13... Delay circuit, 14... Addition circuit, 15... Selection circuit, 16... Subtraction circuit, 17... Multiplication circuit , 18... switching circuit, 19... subtracting circuit.

Claims (3)

[Claims] (1) An analog/digital converter that converts a video signal into a digital signal, a bandpass filter that passes the color signal region from the video signal converted to a digital signal by the analog/digital converter, and an output from the bandpass filter. a first delay circuit that delays the first color signal output by n (n is an integer) horizontal period, and a sum of the first color signal and the first color signal output from the first delay circuit. a first arithmetic circuit that calculates the difference between the two color signals by calculating the difference between the two color signals; a conversion circuit that converts the result output from the first arithmetic circuit into a correlation value of a certain type; and an output from the conversion circuit. A second delay circuit delays the correlation value by m (m is an integer) horizontal period, and the difference between the first color signal and the first color signal outputted from the first delay circuit is calculated as 1. /2; a switching circuit that outputs either the second color signal outputted from the second computing circuit; or the first color signal; a selection circuit that determines whether the signal output from the switching circuit is a third color signal from the correlation value output from the conversion circuit and the correlation value output from the second delay circuit; A video signal separation device characterized in that a luminance signal output is obtained by subtracting the third color signal from the video signal, and a third color signal is used as a color signal output. (2) The length of the first delay circuit is one horizontal period, and the length of the second delay circuit is one horizontal period.
The length of the delay circuit of is one horizontal period, the correlation value output from the conversion circuit is binary with correlation and no correlation, and the content of the selection circuit is when the output of the conversion circuit is correlated and the conversion circuit When the output of the conversion circuit is uncorrelated and the output of the second delay circuit is uncorrelated, the second color signal is selected, and when the output of the conversion circuit is uncorrelated and the output of the second delay circuit is correlated, the first color signal is selected. 2. The video signal separation device according to claim 1, wherein the video signal separation device selects a color signal of . (3) The length of the first delay circuit is two horizontal periods, and the length of the second delay circuit is two horizontal periods.
The length of the delay circuit is two horizontal periods, and the correlation value output from the conversion circuit is two values of correlation and no correlation,
When the content of the selection circuit is that the output of the conversion circuit is correlated, the output of the conversion circuit is uncorrelated, and the output of the second delay circuit is uncorrelated, the second color signal is selected and the conversion circuit selects the second color signal. When the output of the second delay circuit is uncorrelated and the output of the second delay circuit is correlated, the first
2. The video signal separation device according to claim 1, wherein the video signal separation device selects a color signal of .