JP2563952B2 - Luminance signal Color signal separation device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance signal color signal separation device for separating a composite video signal into a luminance signal and a carrier color signal.

[Prior Art] FIG. 3 is a block circuit diagram of a conventional luminance signal / color signal separation device. For convenience of explanation, the PAL system composite video signal will be described. In the figure, (100) is an input to which a digital PAL system composite video signal having a frequency four times as high as the color sub-carrier frequency and whose phase matches the U axis and V axis of the input signal is sampled. The terminals, (201) to (203), input the signal supplied from the circuit in the previous stage to two sampling periods (hereinafter,
First to third 2S delay circuits (hereinafter simply referred to as "delay circuits") for delaying by "2S"), (211), (212)
Is a first and second two-line delay circuit that delays the signal supplied from the circuit in the previous stage by two horizontal scanning periods (hereinafter referred to as "2 lines" or "2H"), and (311) and (312) are the previous stages. The first and second 1/4 multiplication circuits that multiply the signal supplied from the circuit of 1/4 by (1), (321) is the output signal of the second delay circuit (202)
First half circuit for doubling, (401) to (403) are first to third adding circuits for adding the signals of the two systems supplied, (50)
1) to (505) are first to fifth subtraction circuits that perform subtraction between two supplied signals, and (600) is each output of the first and second subtraction circuits (501) and (502). A switching circuit for switching and outputting any one of the signals based on an output control signal of a comparison circuit (900) described later, and (701) and (702) are the absolute values of the signals supplied from the preceding circuits. The first and second absolute value circuits, (800) is a constant generation circuit that generates a certain constant, (90
0) compares the output signals of the second absolute value circuit (702) and the third adding circuit (403) and outputs a control signal for controlling the operation of the switching circuit (600), (101 ) Is a carrier color signal output terminal for outputting a carrier color signal C which is an output signal of the switching circuit (600), and (102) is a fifth subtraction circuit (5
This is a luminance signal output terminal for outputting the luminance signal Y which is the output signal of 05).

Next, the operation will be described. The sample value series of the PAL system composite video signal, which is synchronized with the horizontal scanning frequency and has a frequency four times as high as the color subcarrier frequency, and whose phase matches the U axis and V axis of the input signal, is displayed on the screen. The arrangement is as shown in FIG. The operation of the circuit shown in FIG. 3 will be described with reference to FIG.

Now, from the input terminal (100), the sample value N3 of the sample point S33
If 3 is input, the sample value N32 of the sampling point S32 is output to the output of the first delay circuit (201), and the sample value S23 of the sampling point is output to the output of the first two-line delay circuit (211). Value N23
However, the sample value N22 of the sampling point S22 is output to the output of the second delay circuit (202), and the sample value N21 of the sampling point S21 is output to the output of the third delay circuit (203). Line delay circuit (21
At the output of 2), sample values N12 of sample points S12 are obtained.

The first adder circuit (401) is configured to add the output signal N32 of the first delay circuit (201) and the output signal N12 of the second two-line delay circuit (212), and also the first adder circuit (401). The 1/4 multiplication circuit (311) of the first addition circuit (401) outputs the output signal of 1 /
It is configured to multiply by four. Next 1/2 circuit (321)
Is configured to multiply the output signal N22 of the second delay circuit (202) by 1/2. The first subtraction circuit (50) is 1/2
From the output signal of the multiplication circuit (321), the first 1/4 multiplication circuit (31
In the circuit for subtracting the output signal of 1), the output signal CV of the first subtraction circuit (501) is Becomes

The second adder circuit (402) is configured to add the output signal N21 of the third delay circuit (203) and the output signal N23 of the first two-line delay circuit (211), and 1/4 of 2
The multiplication circuit (312) outputs the output of the second addition circuit (402) to 1/4.
Is configured to double. Second subtraction circuit (502)
Is a circuit that subtracts the output signal of the second 1/4 circuit (312) from the output signal of the 1/2 circuit (321).
The output signal CH of the second subtraction circuit (502) is Becomes

Further, the output signal N32 of the first delay circuit (201) and the output signal N12 of the second two-line delay circuit (212) are supplied to the third subtraction circuit (503), and the third subtraction circuit (503 The output signal of 503) has its absolute value taken by the first absolute value circuit (701). Therefore, the output signal DV of the first absolute value circuit (701) becomes DV = | N32−N12 |.

In addition, the first two-line delay circuit (211) output signal N23
And the output signal N21 of the third delay circuit is supplied to the fourth subtraction circuit (504), and the output signal of the fourth subtraction circuit (504) is the absolute value of the second absolute value circuit (702). Is taken. Therefore, the output signal DH of the second absolute value circuit (702) is
Is DH = | N23−N21 |.

The output signal DV of the first absolute value circuit (701) is supplied to the third adding circuit (403). The constant generator circuit (800)
In a circuit configured to generate a constant K, the constant K
Is a third adder circuit (403) and a first absolute value circuit (70
The output signal DVK of 1) is added to the output signal DVK of the third addition circuit (403).
K becomes DVK = DV + K.

The output signal DVK of the third addition circuit (403) and the output signal DH of the second absolute value circuit (702) are compared with each other by a comparison circuit (900).
Is supplied to. The comparison circuit (900) compares the sizes of DVK and DH, and based on the result, the switching circuit (600).
To the control signal S. The switching circuit (600) has a first
Output signal CV of the subtraction circuit (501) and the second subtraction circuit (5
02) output signal CH is supplied, and the comparison circuit (900)
When DVK, DH is DVK <DH, the first subtraction circuit (5
If the output signal CV of 01) is selected and DVK ≧ DH, the second
The control signal S is sent to the switching circuit (600) so as to select the output signal CH of the subtraction circuit (502). In this way, the comparison circuit (00) detects the direction with a small signal change, which means the direction with high correlation, and outputs the control signal S for selecting the output signal of the filter using the sampling points in the direction with a small signal change. Send out.

The constant K generated by the constant generation circuit (800) is used to prevent the vertical resolution from deteriorating due to the use of the sample values of the sampling points separated by two scanning lines in the vertical direction. By setting the constant K to an appropriate value, it is possible to prevent the vertical resolution from decreasing.

The carrier color signal C which is the output signal of the switching circuit (600) is
It is output from the carrier color signal output terminal (101) and simultaneously supplied to the fifth subtraction circuit (505).

The fifth subtraction circuit (505) is configured to subtract the carrier color signal C, which is the output signal of the switching circuit (600), from the output signal N22 of the second delay circuit (202). The luminance signal Y, which is the output signal of the subtraction circuit (505), is output from the luminance signal output terminal (102).

[Problems to be Solved by the Invention] Since the conventional luminance signal / chrominance signal separation device detects the correlation by using the composite video signal as described above, it is necessary to detect the correlation in the vertical direction. The distance between two sample points corresponds to four scanning lines on the screen. Therefore, in an image that is changing rapidly in the vertical direction, it may not be possible to make an appropriate judgment when detecting the correlation, and as a result, there is a problem that image quality degradation such as cross color and dot interference occurs. I got it.

The present invention has been made to solve the above-mentioned problems, and even in an image that is changing rapidly, it is possible to appropriately detect the correlation, and as a result, the luminance signal and the carrier color signal are accurately detected. An object of the present invention is to obtain a luminance signal / color signal separation device that can be separated.

[Means for Solving Problems] A luminance signal / chrominance signal separation device according to the present invention delays a composite video signal sampled at a frequency synchronized with a horizontal scanning frequency by a plurality of line delay units for each scanning line. Means for simultaneously extracting each sample value of the sample point of interest and a plurality of reference sample points around the sample point of interest, and a reference sample point including the sample point of interest and the sample point located directly above the screen of the sample point of interest. A first vertical / horizontal color signal extraction filter for obtaining a first color signal by extracting frequency components corresponding to components of color subcarriers in the vertical and horizontal directions from each sample value, the sample point of interest, and the above The second color signal is obtained by extracting the frequency components corresponding to the components of the vertical and horizontal color subcarriers from the sample values of the reference sample points including the sample points located right below the screen of the sample point of interest. Second A third color signal is obtained by extracting a frequency component corresponding to a component of the color subcarrier in the horizontal direction from the vertical / horizontal color signal extraction filter and sample values of the sample point of interest and the reference sample points around it. A horizontal direction color signal extraction filter and a first change of a luminance signal mainly in the vertical direction from each sample value of a reference sample point including the sample point of interest and a sample point located right above the screen of the sample point of interest. A first change amount extracting means for extracting an amount, and a luminance signal mainly in the vertical direction from each sample value of a reference sample point including the sample point of interest and a sample point located directly below the sample point of interest on the screen. Second change amount extracting means for extracting the second change amount, and third change for extracting the third change amount of the horizontal luminance signal from each sample value of the reference sample points around the sample point of interest. The amount extraction means and the first to third changes A judging means for outputting a control signal to compare said first
A selection means for selecting the third color signal based on the control signal and outputting it as an output color signal; and a subtracting means for removing the output color signal from the composite video signal and outputting an output luminance signal, The control signal is set so that the second color signal is selected so that the first color signal is selected when the first change amount is minimum.
When the change amount of is the smallest, select the second color signal,
The selecting means is controlled so that the third color signal is selected when the third variation is minimum.

[Operation] The first to third change amount extraction means in the present invention use the low-frequency luminance signal component so that the distance between the two sample points used for detecting the correlation is the scanning line 2 on the screen. Even in an image that has become the main part and is rapidly changing in the vertical direction, an appropriate judgment can be made when detecting the correlation.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same reference numerals as those in the conventional example of FIG. 3 indicate the same or corresponding portions, respectively, and (201) to (208)
Are first to eighth 2S delay circuits for delaying the signal supplied from the preceding circuit by two sampling periods 2S, (213), (214)
Is a first and second 2H-6S delay circuit that delays the signal supplied from the circuit in the preceding stage by 2264 sampling periods (that is, a period obtained by subtracting 6 sampling periods 6S from 2 horizontal scanning periods 2H),
(301) to (306) are the signals supplied from the preceding circuit.
1st to 6th -1/4 times circuits for multiplying 1/4, (311) to (313)
Are the first to third 1/4 multiplication circuits for multiplying the signal supplied from the previous circuit by 1/4, and (321) to (328) are the first to three times the signal supplied from the previous circuit. 1 to 8 1/2 circuit, (40
1) to (405) are first to fifth adder circuits for summing the signals of the three systems supplied, (406) is a sixth adder circuit for adding the signals of the two systems supplied, (501) To (509) are first to ninth subtraction circuits for performing subtraction between the supplied signals of two systems, (600) is a second addition circuit (402), and first and second subtraction circuits (501) , (502) among the output signals, a switching circuit for switching one of the signals based on an output control signal of a comparison circuit (900) described later, and (701) to (703) are signals supplied from the preceding circuit. First to third absolute value circuits that take the absolute value of, (800) is a constant generation circuit that generates a certain constant K,
(900) compares the output signals of the first and second absolute value circuits (701), (702) and the sixth adding circuit (406), and based on the result, the operation of the switching circuit (600). It is a comparison circuit that outputs a control signal for controlling.

Next, the operation of the above configuration will be described. The sample value series of the PAL system composite video signal that is synchronized with the horizontal scanning frequency and has a frequency four times the color sub-carrier frequency and whose phase matches the U axis and V axis of the input signal is displayed on the screen. The arrangement is as shown in FIG. The operation of the circuit shown in FIG. 1 will be described with reference to FIG.

Now, from the input terminal (100), the sample value N3 of the sample point S33
Assuming that 3 is input, the output value of the first delay circuit (201) is the sample value N32 of the sampling point S32, and the output value of the second delay circuit (202) is the sample value of the sampling point S31. N31 is the output of the first 2H-6S delay circuit (213), the sample value N24 of the sampling point S24, and the output of the third delay circuit (203) is S2.
The sample value N23 of the sample point 3 is the sample value N22 of the sample point S22 at the output of the fourth delay circuit (204), and the sample value S21 is the sample value of S21 at the output of the fifth delay circuit (205). The sample value N21 of
The output of the sixth delay circuit (206) is the sample value N20 of the sampling point S20, and the output of the second 2H-6S delay circuit (214) is
The sample value N13 of the sample point S13 is the seventh delay circuit (207).
The sample value N12 of the sample point S12 is obtained at the output of S1, and the sample value N11 of the sample point S11 is obtained at the output of the eighth delay circuit (208).

The first -1/4 multiplication circuit (301) multiplies the signal N33 applied to the input terminal (100) by -1/4 so that the first 1/2 multiplication circuit (321) Delay circuit (201) output signal N32 1
The second -1/4 multiplication circuit (302) is configured to multiply the output signal N31 of the second delay circuit (202) by -1/4 so as to be multiplied by / 2. Next, the first adder circuit (401) calculates the sum of the output signals of the first and second -1/4 multiplying circuits (301) and (302) and the first 1/2 multiplying circuit (321). It works like it does. Therefore, the carrier color signal component C32H which is the output signal of the first addition circuit (401) is Becomes In this way, the first and second -1/4 multiplication circuits (301),
(302), the first 1/2 circuit (321), the first addition circuit (4
01) constitutes a horizontal color signal extraction filter (32H) for extracting the carrier color signal of the sampling point S32.

The third −1/4 circuit (303) is connected to the third delay circuit (20
The second 1/2 multiplication circuit (322) outputs the output signal N22 of the fourth delay circuit (204) to 1 so as to multiply the output signal N23 of 3) by -1/4.
The fourth -1/4 multiplying circuit (304) is configured to multiply the output signal N21 of the fifth delay circuit (205) by -1/4 so that it is multiplied by / 2. Next, the second adder circuit (402)
It operates so as to take the sum of the output signals of the fourth -1/4 multiplying circuits (303) and (304) and the second 1/2 multiplying circuit (322). Therefore, the carrier color signal component C22H, which is the output signal of the second addition circuit (402), is Becomes In this way, the third and fourth -1/4 circuit (303),
(304), the second 1/2 multiplication circuit (322), the second addition circuit (4
02) constitutes a horizontal color signal extraction filter (22H) for extracting the carrier color signal of the sample point S22.

The fifth -1/4 multiplying circuit (305) divides the output signal N13 of the second 2H-6S delay circuit (214) by -1/4 so that the third 1/2
The multiplication circuit (323) outputs the output signal N1 of the seventh delay circuit (207).
The sixth -1/4 multiplying circuit (306) is configured to multiply the output signal N11 of the eighth delay circuit (208) by -1/4 so as to multiply 2 by 1/2. Next, the third adder circuit (403)
It operates so as to take the sum of the output signals of the fifth, sixth -1/4 times circuits (305), (306) and the third 1/2 times circuit (323).
Therefore, the carrier color signal component C12H which is the output signal of the third adding circuit (403) is Becomes In this way, the fifth and sixth -1/4 circuit (305),
(306), the third 1/2 multiplication circuit (323), the third addition circuit (4
03) constitutes a horizontal color signal extraction filter (12H) for extracting the carrier color signal of the sampling point S12.

The fourth 1/2 circuit (324) is the first addition circuit (401).
The fifth 1/2 circuit (32
5) is configured to multiply the output signal of the second adder circuit (402) by half. Next, the first subtraction circuit (501)
From the output signal of the fifth 1/2 times circuit (325) to the fourth 1 /
It operates so as to subtract the output signal of the doubling circuit (324).
Therefore, the carrier color signal component C22B which is the output signal of the first subtraction circuit (501) is Becomes In this way, the fourth and fifth 1/2 circuits (324), (32
5), the first subtraction circuit (501) extracts the carrier color signal of the sample point S22. At times, a color signal extraction filter (22B) in the vertical direction, which focuses on the sample point S32, is configured. In this case, in particular, the input signals of the fourth and fifth 1/2 times circuits (324) and (325) are input to the horizontal color signal extraction filter (32H) for extracting the carrier color signal of the sampling point S32, respectively. The output signals C32H and S22 are the output signals C22H of the horizontal color signal extraction filter (22H) for extracting the carrier color signals of the sampling points. Therefore, the horizontal color signal extraction filters (32H) and (22H) are used.
And a color signal extraction filter (22B) in the vertical direction are connected in series to form a color signal extraction filter called a comb filter (hereinafter, referred to as “first comb filter”) (1).

The fifth 1/2 times circuit (325) is the second addition circuit (402).
The 6th 1/2 circuit (32
6) is configured to multiply the output signal of the third adder circuit (403) by half. Next, the second subtraction circuit (50
2) is the sixth from the output signal of the fifth 1/2 times circuit (325).
It operates so as to subtract the output signal of the 1/2 circuit (326). Therefore, the carrier color component C22T which is the output signal of the second subtraction circuit (502) is Becomes In this way, the fifth and sixth 1/2 circuits (325),
(326), the second subtraction circuit (502) constitutes a vertical color signal extraction filter (22T) for extracting the carrier color signal of the sample point S22, particularly focusing on the sample point S12. In this case, in particular, the fifth and sixth 1/2 times circuits (325),
The input signal of (326) is a horizontal color signal extraction filter (22H) that extracts the carrier color signals of the sampling points S22.
Output signal C22H, output signal C1 of a horizontal color signal extraction filter (12H) for extracting carrier color signals of sample points S12
Since it is 2H, the horizontal color signal extraction filter (22
H), (12H) and vertical color signal extraction filter (22
A color signal extraction filter called a comb filter (hereinafter, referred to as a "second comb filter") (2) is formed by the cascade connection of T).

The switching circuit (600) uses the vertical sampling point S22 and S3
Carrier color signal component C22B, which is the output signal of the first subtraction circuit (501) extracted in anticipation of high correlation between the two sample points
And the carrier color signal component C22T which is the output signal of the second subtraction circuit (502) extracted in the expectation of the high correlation between the sampling point S22 in the vertical direction and the sampling point S12, and in the horizontal direction. Second adder circuit (402) extracted with high correlation
And the carrier color signal component C22H which is the output signal of
Three input signals C22B, C22T, C22H are switched and output according to the output control signal S supplied from the comparison circuit (900).

The operation of the filter selection circuit portion generating the output control signal S will be described below.

The third subtraction circuit (503) operates so as to subtract the carrier color signal component C32H, which is the output signal of the first addition circuit (401), from the output signal N32 of the first delay circuit (201).
Therefore, the low-frequency luminance signal component Y32H which is the output signal of the third subtraction circuit (503) is Y32H = N32-C32H.

The fourth subtraction circuit (504) operates so as to subtract the carrier color signal component C22H, which is the output signal of the second addition circuit (402), from the output signal N22 of the fourth delay circuit (204).
Therefore, the low-frequency luminance signal component Y22H, which is the output signal of the fourth subtraction circuit (504), is Y22H = N22-C22H.

The fifth subtraction circuit (505) operates so as to subtract the carrier color signal component C12H, which is the output signal of the third addition circuit (403), from the output signal N12 of the seventh delay circuit (207).
Therefore, the low-frequency luminance signal component Y12H which is the output signal of the fifth subtraction circuit (505) is Y12H = N12-C12H.

The first 1/4 times circuit (311) multiplies the output signal N24 of the first 2H-6S delay circuit (213) by 1/4, so that the seventh 1/2 times circuit (327) Output signal N23 of the third delay circuit (203)
The second 1/4 circuit (312)
The output signal N22 of the delay circuit (204) is multiplied by 1/4. Next, the fourth adder circuit (404)
It operates so as to sum the output signals of the second 1/4 times circuits (311) and (312) and the seventh 1/2 times circuit (327). Therefore, the low-frequency luminance signal component Y23H, which is the output signal of the fourth adding circuit (404), is Becomes In this way, the first and second 1/4 circuit (311),
(312), seventh 1 / 2-fold circuit (327), fourth adder circuit (4
04) constitutes a horizontal luminance signal extraction filter (23H) for extracting the luminance signal of the sampling point S23.

The second 1/4 times circuit (312) is the fourth delay circuit (204).
The eighth 1/2 circuit (3
28) halves the output signal N21 of the fifth delay circuit (205), and the third ¼ circuit (313) outputs the output signal N20 of the sixth delay circuit (206). It is configured to multiply 1/4. Next, the fifth adder circuit (405) sums up the output signals of the second and third 1/4 multiplying circuits (312) and (313) and the eighth 1/2 multiplying circuit (328). Works like. Therefore, the fifth
The low-frequency luminance signal component Y21H which is the output signal of the adding circuit (405) of Becomes In this way, the second and third 1/4 circuit (312),
(313), eighth 1/2 times circuit (328), fifth addition circuit (4
05) constitutes a horizontal luminance signal extraction filter (21H) for extracting the luminance signal of the sampling point S21.

A sixth subtraction circuit (506) outputs a low-frequency luminance signal component Y22H which is an output signal of the fourth subtraction circuit (504) and a low-frequency luminance signal component Y32H which is an output signal of the third subtraction circuit (503).
Works like subtracting. Next, the first absolute value circuit (701) operates so as to take the absolute value of the output signal of the sixth subtraction circuit (506). Therefore, the output signal DB of the first absolute value circuit (701) becomes DB = | Y22H−Y32H |.

A seventh subtraction circuit (507) outputs a low-frequency luminance signal component Y22H which is an output signal of the fourth subtraction circuit (504) to a low-frequency luminance signal component Y12H which is an output signal of the fifth subtraction circuit (505).
Works like subtracting. Next, the second absolute value circuit (70
2) operates so as to take the absolute value of the output signal of the seventh subtraction circuit (507). Therefore, the second absolute value circuit (70
As for the output signal of 2), DT becomes DT = | Y22H-Y12H |.

The eighth subtraction circuit (508) outputs the low-frequency luminance signal component Y23H, which is the output signal of the fourth addition circuit (404), to the low-frequency luminance signal component Y21H, which is the output signal of the fifth addition circuit (405).
Works like subtracting. Next, the third absolute value circuit (70
3) operates so as to take the absolute value of the output signal of the eighth subtraction circuit (508). Therefore, the third absolute value circuit (70
The output signal DH of 3) becomes DH = | Y23H-Y21H |.

The output signal DH of the third absolute value circuit (703) is supplied to the sixth adding circuit (406). The constant generator circuit (800)
The output signal K of the constant generation circuit (800) is supplied to the sixth addition circuit (406) in a circuit configured to generate a predetermined constant K. The sixth adder circuit (406) is
It is configured to add the output signal DH of the third absolute value circuit (703) and the output signal K of the constant generation circuit (800), and thus the output DHK of the sixth addition circuit (406).
Becomes DHK = DH + K.

The comparison circuit (900) has a vertical sampling point S22,
The output signal DB of the first absolute value circuit (701), which means the change amount of the low-frequency luminance signal component between the sampling points S32, and the low range between the sampling points S22 and S12 in the vertical direction. The output signal DT of the second absolute value circuit (702), which means the change amount of the luminance signal component, and the change amount of the low-frequency luminance signal component between the sampling points S23 and S21 in the horizontal direction. Three signals of the output signal DHK of the sixth adding circuit (406) are supplied. A comparison circuit (900) compares the magnitudes of these three signals and determines the smallest signal among them. When the output signal DB of the first absolute value circuit (701) is the minimum, the carrier color signal component C22B which is the output signal of the first subtraction circuit (501).
The pulse code corresponding to the second absolute value circuit (702)
If the output signal DT of the
The pulse code corresponding to the carrier color signal component C22T, which is the output signal of 2), is output to the output signal DHK of the sixth adding circuit (406).
When is the minimum, the pulse code corresponding to the carrier color signal component C22H which is the output signal of the second addition circuit (402) is generated and sent as the control signal S to the switching circuit (600).

In this way, the filter selection circuit portion detects the correlation of the low-frequency luminance signals and selects the color signal extraction filter configured by using the sample value of the sample point having the highest correlation. The constant K generated by the constant generation circuit (800) is
It prevents the vertical resolution from deteriorating by using the sampled values of two scanning lines apart from the vertical direction. By setting an appropriate value in the constant generation circuit (800), It is possible to prevent a decrease in resolution.

The switching circuit (600) uses a control signal S supplied from the comparison circuit (900) to obtain a carrier color signal C22 obtained by using an optimum carrier color signal extraction filter at the sampling point.
Output from the carrier color signal output terminal (101),
It is supplied to the ninth subtraction circuit (509).

The ninth subtraction circuit (509) operates to subtract the carrier color signal C22, which is the output signal of the switching circuit (600), from the output signal N22 of the fourth delay circuit (204). Therefore, the ninth
The luminance signal Y22, which is the output signal of the subtraction circuit (509), becomes Y22 = N22−C22. The luminance signal Y22, which is the output signal of the ninth subtraction circuit (509), is output from the luminance signal output terminal (102).

In the above embodiment, the digital PA is used as the input signal.
The case where the L system composite video signal was applied was shown.
The delay time of the second 2H-6S delay circuits (213) and (214) is
From 2264 sampling periods (2 horizontal scanning periods-6 sampling periods)
For a digital NTSC composite video signal obtained by sampling an NTSC composite video signal at a frequency four times the color subcarrier frequency by replacing it with 904 sampling cycles (1 horizontal scanning cycle-6 sampling cycles). Can also be applied.

[Advantages of the Invention] As described above, according to the luminance signal / chrominance signal separation device of the present invention, the composite video signal sampled at the frequency synchronized with the horizontal scanning frequency is divided into a plurality of line delays for each scanning line. A means for simultaneously extracting each sample value of the sample point of interest and a plurality of reference sample points around it, and a reference sample including the sample point of interest and the sample point located right above the screen of the sample point of interest A first vertical / horizontal direction color signal extraction filter for obtaining a first color signal by extracting frequency components corresponding to the components of the color subcarriers in the vertical direction and the horizontal direction from each sample value of the point; And the second color signal by extracting the frequency component corresponding to the component of the color subcarrier in the vertical direction and the horizontal direction from each sample value of the reference sample point including the sample point located right below the screen of the sample point of interest. Get first A third color signal by extracting a frequency component corresponding to a component of a horizontal color subcarrier from the sample values of the vertical and horizontal color signal extraction filters 2 and reference sample points around the sample point of interest and the surrounding sample points. And a horizontal color signal extraction filter that obtains the sampled value of the reference sampled point including the sampled point of interest and the sampled point located immediately above the sampled point of interest on the screen. To extract the amount of change in
From the sample values of the reference sample points including the sample points of interest and the sample points located right below the screen of the sample points of interest, and the second change amount of the luminance signal mainly in the vertical direction. Second change amount extracting means for extracting, third change amount extracting means for extracting a third change amount of the luminance signal in the horizontal direction from each sample value of reference sample points around the sample point of interest, and Determining means for comparing the first to third variation amounts and outputting a control signal; and selecting means for selecting the first to third color signals based on the control signals and outputting the output color signals. Subtraction means for outputting the output luminance signal by removing the output color signal from the composite video signal, and the control signal selects the first color signal when the first change amount is minimum. , The second color signal is selected when the second variation is the minimum. In addition, by controlling the selecting means so that the third color signal is selected when the third change amount is the minimum, the correlation is detected by using the low-frequency luminance signal component. Since it is configured, the correlation detection can be performed with good performance, and there is an effect that it is possible to realize an accurate luminance signal / color signal separation device without cross color or dot interference.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, and FIG. 2 is a sampling sequence when a PAL system composite video signal is synchronized with a horizontal scanning frequency and is sampled at a frequency four times the color subcarrier frequency. FIG. 3 is a block circuit diagram of a conventional luminance signal / color signal separation device, showing a two-dimensional array on the screen. (1) ... 1st comb filter, (2) ... 2nd comb filter, (12H), (22H), (32H) ... horizontal color signal extraction filter, (22B), ( 22T) ... vertical color signal extraction filters, (21H), (23H) ... horizontal luminance signal extraction filters, (201) to (208) ... 2 sampling period delay circuits, (213), ( 214) ... 2 horizontal scanning periods-6 sampling period delay circuits, (301) to (306) ... -1 /
4x circuit, (311) ~ (313) ... 1 / 4x circuit, (321) ~
(328) ... 1/2 times circuit, (401)-(406) ... adding circuit, (501)-(509) ... subtraction circuit, (600) ... switching circuit, (701)-(703) …… Absolute value circuit, (800) ……
Constant generator, (900) …… Comparison circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A sampled value of a sample point of interest and a plurality of reference sample points around it by delaying a composite video signal sampled at a frequency synchronized with a horizontal scanning frequency by one scanning line by a plurality of line delay devices. Corresponding to the component of the color subcarrier in the vertical and horizontal directions from each sample value of the reference sample point including the sample point of interest and the sample point located right above the screen of the sample point of interest. A first vertical / horizontal color signal extraction filter for extracting a frequency component to obtain a first color signal, and a reference sample including the sample point of interest and a sample point located directly below the sample point of interest on the screen. A second vertical / horizontal color signal extraction filter for obtaining a second color signal by extracting frequency components corresponding to the components of the color subcarriers in the vertical and horizontal directions from each sample value of the point; and A horizontal color signal extraction filter for obtaining a third color signal by extracting the frequency component corresponding to the component of the color subcarrier in the horizontal direction from each sample value of the reference sample points in the vicinity of A first change amount extracting means for extracting a first change amount of a luminance signal mainly in the vertical direction from each sample value of a reference sample point including a sample point located right above the screen of the sample point; Second change amount extraction means for extracting the second change amount of the luminance signal mainly in the vertical direction from each sample value of the reference sample point including the sample point and the sample point located directly below the sample point of interest on the screen. And a third change amount extracting means for extracting a third change amount of the luminance signal in the horizontal direction from each sample value of reference sample points around the sample point of interest, and the first to third change amounts. Determination means for comparing and outputting a control signal; And a subtracting means for removing the output color signal from the composite video signal and outputting an output luminance signal. The signal is selected such that the first color signal is selected when the first change amount is minimum, and the second color signal is selected when the second change amount is minimum. The luminance signal chrominance signal separation device is characterized in that the selecting means is controlled so that the third color signal is selected when the change amount of is the smallest.