JPH04105494A - Luminance signal/chrominance signal separator - Google Patents

Abstract

PURPOSE:To improve the quality of a reproduced picture by providing a signal switching control means to the above circuit, in which a board and luminance signal generated from a 1st signal delay means is outputted in place of a board band luminance signal obtained from an adder circuit when absence of vertical correlation in the luminance signal is detected by a detection means and a chrominance signal generated from a 2nd delay means is outputted in place of a chrominance signal separated by a comb-line filter circuit. CONSTITUTION:Switches 14, 15 are turned to the position of a terminal (b), then a broad band luminance signal Y outputted from an adder 6 and a chrominance signal C outputted from an inversion circuit 13 are outputted to a post-stage from a terminal C. However, when a non-correlation part of the luminance signal is detected and a non-correlation detection circuit 10 outputs a switch changeover signal 50, the switches 14, 15 are turned to the position of a terminal (a), and a broad band luminance signal Y subject to 1H delay outputted from an adder 11 and a chrominance signal C subject to 1H delay outputted from a 1H delay circuit 12 are outputted to a post-stage from the terminal C.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a luminance signal/chrominance signal separation method for separating luminance signals and chroma signals from a composite video signal in television receivers, video tape recorders, etc. Regarding circuits.

(Prior Art) Conventionally, this type of luminance signal/chrominance signal separation circuit (hereinafter referred to as a Y/C separation circuit) has a band whose center frequency is the chroma subcarrier from a composite video signal 100, as shown in FIG. There is a method in which a pass filter 1 extracts a chroma signal C, and a low pass filter 2 extracts a luminance signal Y. However, this method has drawbacks such as the high-frequency components of the luminance signal Y being cut, and the high-frequency components of the luminance signal Y being added to the chroma signal C, resulting in the occurrence of cross color. .

Therefore, in order to avoid this drawback, as shown in FIG. After separating, the high frequency component YH is added to the low frequency component Y1- of the luminance signal extracted by the low bass filter 2.
There is a method of obtaining a wideband luminance signal Y by adding the following in an adder 6. However, ], F() means - horizontal scanning period. However, in this method, the chroma signal component (
(color subcarrier) remains and dot interference appears,
There were drawbacks such as deterioration of vertical color resolution.

(Problem to be Solved by the Invention) In the latter example above, in the Y/C separation circuit having the conventional comb filter described in The color sub-color signal is mixed with the high-frequency component of the luminance signal, and this appears as dot interference on the TV/TV screen, resulting in an extremely unsightly screen. There is a drawback that the color signal in the correlated portion is mixed with the color signal of the previous line, and the high frequency component of the luminance signal in this portion is added to the color signal. '' and (1), there were drawbacks such as the occurrence of cross colors5. Therefore, the present invention eliminates the above drawbacks, and eliminates dot interference in the luminance signal and color signal 4. It is an object of the present invention to provide a luminance signal/color signal separation circuit that improves the quality of reproduced images by reducing color mixture and cross color.

[Structure of the invention]

(Means for Solving the Problems) The present invention generates a mixed signal jtl, . A comb-shaped filter circuit separates this mixed signal into a color signal and a high-frequency component of luminance (No. 8) by using the vertical correlation of the mixed signal; In a luminance signal/chrominance signal separation circuit having an addition circuit that adds a low frequency component and a high frequency component of the luminance signal to obtain a broadband luminance signal, the broadband luminance signal obtained one horizontal scanning period before the broadband luminance signal; a first signal delay means for creating a signal; a second signal delay means for creating a color signal one horizontal scanning period earlier than the color signal; and a detection means for detecting that there is no vertical correlation in the luminance signal. , during a period in which the detecting means detects that there is no vertical correlation in the luminance signals, a broadband luminance signal output from the first signal delaying means is output in place of the broadband luminance signal obtained from the adding circuit. The apparatus also includes a signal switching control means for outputting a color signal separated from the second delay means in place of the color signal separated by the comb filter circuit.

(Function) In the luminance signal/chrominance signal separation circuit of the present invention, the first signal delay means generates the front-bottom area luminance (7:1) of the J water shell scanning period plane from the broadband luminance signal. The second signal delay means creates a color signal for the water V scanning period from the color signal.The detection means detects that there is no vertical correlation in the luminance signal C6''. During a period in which it is detected by the means that there is no vertical correlation in the luminance signals, the broadband luminance signal output from the first signal delaying means is output in place of the broadband luminance signal obtained from the adding circuit; A color signal separated by the second delay means is output instead of a color signal separated by the comb filter circuit.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. I will explain. FIG. 1 is a block diagram showing an embodiment of the luminance signal 2/chrominance signal separation circuit of the present invention. 1 is the color signal C and the high frequency component Y of the luminance signal from the composite video signal 100.
2 is a low-pass filter that extracts the low-frequency component Yl of the luminance signal from the composite video signal 100; 3.7.8.12 is a bandpass filter that extracts the input signal IH;
-11 delay circuit, 4.6.1
-1 is an adder that adds two input signals, 5.9 is a subtracter that subtracts two input signals, and 10 is a waveform of the input uncorrelated signal to generate a switching control signal for switch 14.15. 4.15 is a switch for switching the signal flow.

Here, the bandpass filter]. , low pass filter 2
] H delay H circuit 3, adder 4 and subtracter 5 constitute a comb filter circuit, X, IHH delay circuit 7
．． 8 and adder 1.1 convert the first signal delay means to 1, H
Delay circuit B], 2 constitute a second signal delay means, the LH delay circuit 7 and subtracter 9 constitute a detection means, and the decorrelation detection circuit 10 and the switch 184.15 constitute a signal switching means. .

Next, the operation of this embodiment will be explained. The bandpass filter 1 extracts a signal in which the color signal C and the high frequency component YH of the luminance signal are mixed from the composite video signal inputted to the Y/C separation circuit] 11, and converts this mixed signal into the ]H delay circuit' 3. Output to a comb filter composed of an adder 4 and a subtracter 5. This comb-shaped filter has an input of 11
Using the 'twin correlation in the vertical direction of the signal, YH of the luminance signal is separated by adder 1 and output, and the chrominance signal C is separated and output by subtracter 5. do.

On the other hand, the low-pass filter 2 extracts the low-frequency component Yl of the luminance signal from the digital video signal 100,
This is outputted to the LHH extension circuit 7, adder 6, and subtracter 9. Adder 6 has adder 1 or t.

The high-frequency component Yi(t) of the output luminance signal is included.
2- Therefore, the low-frequency component Y18 and the high-frequency component YH of the luminance signal are added together to form a wideband luminance signal Y6.
, this broadband luminance (No. 3)' is sent to the terminal of the switch 14.

Further, the high-frequency component YH of the luminance signal i·' output from the adder 4 is input to the LHH delay circuit 8G, delayed by 1H, and then input to the adder 11-. j′1. The low-frequency component YL of the luminance signal is inputted to the adder 1 by the IHH delay circuit 7 with a delay i'1. Therefore, the adder]1 is 1.

Low frequency component Y1 and high frequency component YH of the luminance signal delayed by 1H
are added, and the delayed broadband luminance signal Y is output to the terminal a of the switch 1.4 and the subtracter 9. Therefore, the subtracter 9 outputs the IH-delayed broadband luminance signal Y. The low-frequency component YL of the luminance signal is subtracted from the signal Y to extract the non-correlated part of the luminance signal, which is input to the non-correlation detection circuit 0. By the way, the color signal C extracted from the subtracter 5 is IH delay circuit F#11.,2
It is inputted to the terminal a of the switch 15 after a delay of H, and the polarity is inverted by the inverting circuit 13 and the switch]5
input to the terminal.

Non-correlation detection circuit] 0 performs waveform shaping of the input non-correlation portion and converts it into a switch switching control signal and 1. ,,71 After that, apply this to the switching control terminal of switch]4.15. Normally, the switch 4.15 is located on the terminal mountain side, and outputs the broadband luminance signal Y output from the adder 6 and the color signal C output from the inverter 3 from the terminal C to the subsequent stage. 2 or 1-5 During the period when the non-correlated part of the luminance signal is detected and the switch switching signal 50 is output from the non-correlation detection circuit 10, the switch 14.15 is set to the end r:2] side g.
,,l: switched and outputted from the adder 1] H-delayed broadband luminance signal Y, and II-(delay circuit) outputted from the IH-delayed chrominance signal 72. C is output from each end r-c to the subsequent stage.The switch 14.1
．． 5 indicates that the terminal is switched to the terminal a side immediately after the switch switching signal 50 is no longer output.

FIG. 2 is a diagram showing the flow between No. 13 and No. 114 in the Y/C separation path. Figure 5. Assume that the original signal (original signal) is flowing in the order of -1, Oll, and 2 lines.1, each contains the luminance signal low frequency component (y,), the luminance It is assumed that the image contains a range component (directly yH) and a color signal (C). The number 0 in Y, o to 1 indicates the picture content 7, and if the same number continues, it is assumed that signals with vertical correlation continue. The number -1 indicates the line number of the original signal. Therefore, this case shows a case where the signal changes to signal 1 without vertical correlation at line 1, and then a signal with vertical correlation continues again at line 1, that is, a case where the signal changes rectangularly in the vertical direction. The meanings of the numbers for YH and C are also the same. The signals output after Y/C separation and further IH delay are as shown in the figure. Y
Y[110((YHII +
Y)+00 > 72+ (C11C00) / 2
), (C11C□(>)/2+(YHH "HOO" 2, the signal of a different picture is added to the YH signal at t'L, and the uncorrelated part of the color signal (C1, -C6°) /'2
is further added, indicating that waveform rounding and dot interference occur in the luminance signal. In the color signal, colors of different patterns are added, indicating that the colors are mixed, and the uncorrelated portion of Yti of (YHll YHoo)/2 is added, indicating that chroma color is generated. Here, it appears in YH in the vertical correlation part (C,
,1iI-C,m,,,1)/2 and (YH,
III-Y, , 1-1> /2 (II, n is an integer)
is O if there is a vertical correlation and is omitted.

According to this embodiment, in the picture switching part (non-correlation part), when the non-correlation detection circuit 1o detects this, the switches 14 and 15 are switched to the terminal a side, and the correlated part before IH is switched. Since it is replaced with the wideband luminance signal Y, the color subcarrier signal is mixed with the high frequency component YH of the luminance signal, and this can be prevented from appearing as dot interference on the television screen. Also, the luminance signal Y is
When replacing the signal with the signal before HH, the color signal C is also replaced by the signal before IHH, so the high frequency component YH of the luminance signal is added to the color signal C due to the non-correlation of the picture switching section. It is possible to prevent the occurrence of cross colors caused by
It is possible to prevent color mixing with the signal of the previous line. Therefore, the quality of the image can be significantly improved compared to the conventional method.

FIG. 3 is a block diagram showing another embodiment of the present invention. In this example, the low frequency component Y1- and the high frequency component YH of the luminance signal are
is added in the adder 11 located after the switch 14, so that the low-frequency component Y[ of the IH-delayed luminance signal is used at any time to make the low-frequency component Y[] continuous in time. While maintaining the same effect as the previous embodiment, the adder 6 which was necessary in FIG.
The circuit can be simplified by reducing the In the signal shown in FIG. 2, Y, 12 in the non-correlation replacement section of the fourth output line of this example is changed to Y, 11.

FIGS. 4 and 5 are block diagrams showing still other embodiments of the present invention. 1-H delay circuit 3 forming a comb circuit
Furthermore, an IHH delay circuit 16 is connected in series, and the adder 4 of this circuit takes out the high frequency component YH of the luminance signal, the subtracter 5 takes out the chrominance signal C, and the adder 17 takes out the IH delay component of the luminance signal. Since the IH delay signal C of the color signal is taken out from the subtracter 18, the high frequency component YH obtained by The number of circuits can be reduced and the circuit can be further simplified, and the same effect as in the previous embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the luminance signal/chrominance signal separation circuit of the present invention, the rounding of the luminance signal waveform, the dot interference, and the color mixture of the chrominance signal, which occur in areas without vertical correlation during Y/C separation, can be avoided.
Can reduce cross-color and get a good television picture. 7 can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the Y/C separation circuit of the present invention, FIG. 2 is a diagram showing the time flow of signals in the Y/C separation circuit shown in FIG. 1, and FIG. 3 is a block diagram showing another embodiment of the present invention, FIGS. 4 and 5 are block diagrams showing still other embodiments of the present invention, and FIG. 6 is a conventional luminance signal/color diagram. FIG. 7 is a block diagram showing another example of a conventional luminance signal/chrominance signal separation circuit. 1...Band pass filter 2...Low pass filter 3.7.8.12...IHH extension circuit 4.6.11.17...Addition circuit 5.18...Subtraction circuit 13... Inverting circuit 14.15...Switch agent Patent attorney Rule Ken Chika Yudo Hiroshi UjiFigure 6Figure 7

Claims (1)

[Claims] A filter circuit that separates a low-frequency component of a luminance signal from an input composite video signal and separates a mixed signal in which a color signal and a high-frequency component of the luminance signal are mixed, and a vertical correlation of the mixed signal is utilized. a comb filter circuit that separates high-frequency components of the color signal and luminance signal from this mixed signal, and an addition circuit that adds the low-frequency components of the luminance signal and the high-frequency components of the luminance signal to obtain a wideband luminance signal. a luminance signal/chrominance signal separation circuit having a first signal delay means for creating a broadband luminance signal one horizontal scanning period before the broadband luminance signal; and a first signal delaying means for creating a broadband luminance signal one horizontal scanning period before the color signal; a second signal delay means for creating a signal; a detection means for detecting that there is no vertical correlation in the luminance signal; and a second signal delay means for detecting that there is no vertical correlation in the luminance signal; A broadband luminance signal created by the first signal delaying means is output in place of the broadband luminance signal obtained from the circuit, and a broadband luminance signal created by the second delaying means is produced in place of the color signal separated by the comb filter circuit. 1. A luminance signal/chrominance signal separation circuit comprising a signal switching control means for outputting a color signal.