JPH01206794A - Video signal processing circuit - Google Patents

Abstract

PURPOSE:To surely obtain color information by detecting a signal for inversion of hue in the vertical direction of a picture to prevent the occurrence of dot disturbance on the boundary of hue. CONSTITUTION:A color signal and a high band Y signal are obtained from a composite video signal by a wide band filter 50. Signals of 1H and 2H before of the signal on the current line are obtained by 1H delay circuits 50 and 70, and the signal for a pattern where hue is inverted in the vertical direction of the picture is detected in an operating means consisting of MAXs 72 and 75, MINs 73 and 74, an inverter 71, and an adder 76 by these outputs. An operating means consisting of MAXs 52-54, MINs 56-59, an inverter 79, adders 60-63 and 78, subtractors 64 and 77, a delay device 66, and a narrow band filter 65 takes out the color signal with a wide band characteristic as it is in case of the presence of vertical correlations and gives a narrow band characteristic to the color signal to take out it in case of the absence of vertical correlations and takes out the color signal and a luminance signal as '1' and '0' respectively in case of the pattern where hue is inverted in the vertical direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to, for example, a VTR, etc., in which a Yc (luminance) signal and a Cc (carrier color)
This relates to a YC component 111 circuit that separates and extracts signals.

Prior Art FIG. 5 shows a circuit diagram of a circuit previously proposed by the present applicant in Japanese Patent Application No. 1982-265885 (title of invention "Video Signal Processing Circuit"). A wideband filter 50 separates the video signal from the combo gino 1 to obtain a color signal and a high-frequency Y signal, and 1)-(delay circuit 5
1. MAX52-55, MIN56...59, adders 60-63, reducer 64, delay circuit 66, narrowband filter 65 output from wideband filter 50) has a vertical correlation with the color signal If there is a vertical correlation, the color signal is extracted with its wideband characteristics as it is, and if there is no vertical correlation, the color signal is extracted with a narrowband characteristic.

In FIG. 5, 52 to 55 are high potential detection circuits (hereinafter referred to as MA
X), and has the configuration shown in Figure 8 (A>),
Outputs the higher potential of the two power sources. 56
. . . 5 is a low potential output circuit (hereinafter referred to as MIN), which is 1F4 shown in FIG. 8(B) and outputs the lower potential of the two circuits.

As shown in Fig. 6, when there is a vertical correlation of color signals such as color par, the wideband C'' signal Cw indicating that there is vertical correlation of the color signals is 1, and the high band Y signal is 1. There is no vertical correlation, and the YH times signal becomes O. Therefore, the signal CN becomes O, and the signal CIAI is extracted as a wideband C signal (*1). On the other hand, when there is no vertical correlation between the color signal and the Y signal in a fine image such as normal outdoor wind silver, the broadband C com signal Cw becomes O, YH times the signal O, and therefore the signal CN becomes 1, and the signal CN is extracted as a narrowband C signal (*2).

In this way, optimal band characteristics can be obtained depending on the presence or absence of vertical correlation.

Problems to be Solved by the Invention For example, when obtaining an image in which the hue is reversed from green to magenta in the vertical direction of the screen as shown in FIG. 7, two 11-1 delay circuits are installed after the wideband filter 50 shown in FIG. Setup [
If the current line is n, one line before is (n-1>, and two lines before is (n-2)), then in an image where vertical correlation disappears as shown in the figure, n = -1, (n-1) = l, (n=2)
--1. However, in the circuit shown in FIG.
Since only one delay circuit is provided, n and (n
−1), n=1, (rl−1
)=1, (n-2)=O, then n=1, (n-1)=
1, (n-2>=1, n=1, (n-1>=1,
(n-2)--1 is not distinguished, and in all these cases, C0UT=O and YOUT=1 are output (*3 in Fig. 6).

Therefore, when obtaining an image in which the hue is reversed in the vertical direction of the screen as shown in FIG. accidentally leaked into the Y signal and hit the driver 1~ on the line between the green and magenta.
There were problems in that interference occurred and color information was lost.

According to the present invention, when obtaining an image in which the hue is reversed vertically on the screen, color information can be reliably obtained without causing dot interference at the boundary between hues, and furthermore, the vertical correlation of color signals can be improved. Optimum band characteristics can be obtained for both the presence and absence, and as a result, in the case of vertical correlation, it is possible to obtain a broadband color signal 8 to improve the cross luminance in the color bar and the frequency characteristics of the color signal. In the case of no vertical correlation, the purpose is to provide a YC separation circuit that does not cause blurring of fine image details and has less cross color. The wideband filter 50 is a means for separating the composite video signal to obtain color signals and high MY signals, 1H.
Delay circuit 51. , 70 is N (N=1, 2-) for the normal line signal which is the output of the wideband filter 50.
Signal before line (n-1) and signal before 2N lines (n
-2), MAX72,75, MIN73,7
4. Inverter 71 and adder 76 are broadband filters 50
MAX5; a first calculating means for detecting a signal in the case of an image situation in which the hue is reversed in the vertical direction of the screen from the output of MAX5, the signal N lines before (n-1), and the signal 2N lines before (n-2);
2.~54, MIN56~59, inverter 79, adders 60, 61, 63, 78, subtracter 64, . 77, delay circuit 6G, narrowband filter 65 is wideband filter 50
Detects whether or not there is a vertical correlation with respect to the color signal from the output of If there is no vertical correlation, the color signal is extracted with a narrowband characteristic, and if the image is such that the hue is reversed at least in the vertical direction of the screen, the color signal is set to "1", and the luminance is set to "1". 3A and 3B are examples of second arithmetic means for extracting a signal as "0";

In the case of an image in which the hue is reversed in the vertical direction of the screen as shown in FIG. 7, the signal n of the current line, the signal (n-1) of the previous line,
The signal 2 lines before (n-2> is n=・1.n-1=-
1, n-2--1, and only in this combination the output Xc of the first computing means becomes 1, and at this time YH-1, Cw
= 0, so Yz' = O, CF = 1, and thus Cc-1, Yc = O. Therefore, it is possible to prevent the occurrence of dora 1~ at the boundary between hues (Yc=O)
You can prevent 1F from losing color information anywhere (Cc=1>
.

On the other hand, if there is a vertical correlation like a color bar,
Wide +14 I C-1 mu signal Cw is 1, Y+-+-0
Since ゜Xc = O, the YH' signal becomes 0, so CF
becomes 0, and the signal Cw is extracted as a wideband signal multiplied by Cc. On the other hand, when there is no correlation between the center of gravity of the color signal in a fine image such as a normal outdoor scene, the broadband C-com signal Cw is O,
Y) I =0. From Xc = O, YH' signal bo becomes,
Therefore, the signal C)- becomes 1, and the signal CF becomes narrowband C
The signal is extracted c times. In this way, optimal band characteristics can be obtained depending on the presence or absence of vertical correlation.

Embodiment FIG. 1 shows a block diagram of the first embodiment (non-average comb filter) of the circuit of the present invention. In the figure, the same parts as in FIG. .

In the figure, the output signal of the wideband filter 50 (n current line), the output signal of the one-day delay circuit 51 (n-1>(1
line), and the output signal of the one-day delay circuit 70 (n-2
) (2 lines before) is inverted by an inverter and the signal is MAX.
72. The highest potential and the lowest potential are taken out respectively, and the output of MAX72 is supplied to MIN74.
The output of MIN73 is compared with the reference potential (zero in the figure) and the lower potential is taken out.
(zero in the figure) and the higher potential is extracted. M.A.
The output of X75 and the output of M I N, 74 are connected to the adder 76.
, and is supplied to a subtracter 77 as a signal Xc. In the subtracter 77, the output signal Xc of the adder 76 is subtracted from the output signal YH of the adder 61 to obtain the signal YH'. It is added to the signal YH' at the subtracter 64, and subtracted from the output of the wideband filter 50 at the subtracter 64 to obtain the signal CF, which is then supplied to the Δt2 delay circuit 66.

The inverter 79 inverts the output of the 11-(delay circuit 51), and is the same as the output of the 1-to-1 delay circuit 51 inputted to MAX52 and MINb6 with negative polarity in FIG.

The output CF of the subtracter 64 is supplied to the adder 63 via a narrowband filter 65, added to the output of the delay circuit 66, and taken out from the output terminal 4 as a signal multiplied by Cc.

On the other hand, the composite video signal input to the terminal 1 passes through the N detour 67, which includes the delay times of the wideband filter 50 and the narrowband filter 65, and extends the delay time of the hill 1 (Δ↑1→-j2). The signal is supplied to a subtracter 68, where the Cc multiplied signal is subtracted, resulting in a Yc low signal, which is output from the output terminal 8.

Here, output signal Xc of adder 76, output signal Cw of adder 60, output signal YH1 of adder 61, output signal YH' of subtracter 77, output signal CF of subtracter 64, adder 63
line n, <n-1>, (
The truth values for each potential of n-2) are as shown in FIG.

In particular, as shown in FIG. 7, the image condition in which the hue is reversed in the vertical direction of the screen is shown in *10 in FIG. 2 when tn=i.

(n-1>=1.<n-2)--1, and in the present invention, it is Xc-1 only in such a case, and O in other combinations. Therefore *11. *As shown in 12, n=
1. Even if (n-1)=1, other combinations, that is, (n
-2)=・0. (n-2)-1), Cc = O,
Yc = 1, n-1, (n-1) = 1. (n-2
)-1 only when Cc=1. When Yc=O, it is possible to prevent dots from appearing on the boundary between hues (Yc-0), and also to prevent color information from disappearing (Cc=1).

Also, one day delay circuit is added compared to the circuit shown in Fig. 5, but since it can be a conventional general-purpose inexpensive glass delay line that passes only the color signal band, It will not increase costs. Since this is a configuration in which a truth value is obtained without particularly providing a 1H delay circuit in the luminance signal thread path, the two 11-1 delay circuits can be glass delay lines that pass through the chrominance signal band.

On the other hand, especially in the case of an image with a vertical correlation to the C signal, such as color par, the signal n is "1" and the signal (n=1) is r
-Ll, and the output signal Cw of the adder 6o is r 1 J
, the output signal Yl-1' of the subtracter 77 becomes "Ol, and the output signal Cp of the subtracter 64 becomes rOJ. Therefore, the adder 6
The output of signal Cw becomes "1" and is taken out from terminal 4 as signal Cw [1-1 is wideband CcC signal 1(w))].

“The output “1” of the extension circuit 67 is the CcC signal 1 in the subtracter 68.
1-1 is subtracted, and the YcC signal of l-OJ is taken out from terminal 8.

In addition, in the case of a random image with no vertical correlation in the C signal, such as for normal outdoor wind, the signal n is considered to be "1", and the signal (n=1) is considered to be "01", and the output signal Cw of the adder 6o is is “O”
, the output signal YH' of the subtracter 77 is 1-O'', the subtracter 6
The output signal CF of No. 4 becomes [1-1. Therefore, the narrowband Ccc signal 1(N) of "1" is output from the narrowband filter 65.
is extracted as Since the signal Cw is "0", the narrowband CcC signal is taken out from the adder 63 as it is, and is taken out from the terminal 4J. The output "1" of the delay circuit 67 is subtracted by the "CcC signal 1-1" in the subtracter 68, and
The cC signal is output from terminal 8.

In this way, as a C signal band filter, if there is vertical correlation, it becomes a wide band filter and can obtain a wide band C signal output, thus improving the cross luminance in the color par and the frequency characteristics of the C signal. On the other hand, if there is no vertical correlation, it becomes a narrowband filter and a narrowband C
Therefore, blurring of fine image details does not occur, and in other words, optimum band characteristics can be obtained depending on whether vertical correlation exists or not.

FIG. 3 shows a block diagram of a second embodiment (non-average comb filter) of the circuit of the present invention, in which the same parts as in FIGS. 1, in which the output Xc of the adder 76 is inverted by the inverter 80 and the explanation thereof is omitted.
9. The output YH' of the subtracter 77 shown in FIG. 1 is obtained from the adder 61. The operation and effect of the counters are respectively similar to those of FIG.

FIG. 4 shows a block diagram of a third embodiment (non-average comb filter) of the circuit of the present invention, in which FIGS. 1, 3,
The same parts as in FIG. 5 are denoted by the same numbers and symbols, and their explanation will be omitted. In this device, the output Xc of the adder 76 is inverted by an inverter 81 and its level is reduced to 1/2, and is supplied to the MIN58°MAX571 to obtain the output Cw from the adder 60. Other operations and effects are similar to those in FIG. 1.

Although each of the above embodiments is applied to the N'rSC system, it can be similarly applied to the PAI system if a 21-1 delay circuit is used instead of the 11'' delay circuit.

Effects of the Invention According to the present invention, dot interference does not occur at the boundary line in an image where the hue is reversed in both directions of the screen, color information is not lost, and the vertical Optimal band characteristics can be obtained depending on whether there is a correlation or not. As a result, when there is a vertical correlation, the cross luminance in the color par and the frequency characteristics of the color signal can be improved, whereas when there is no vertical correlation, the frequency characteristics of the color signal can be improved. This method does not cause blurring of fine image details, and since the band of the color signal is narrow, it is possible to reduce cross colors.Furthermore, it can be realized with a simple circuit and is low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the first embodiment of the circuit of the present invention, FIG. 2 is a diagram showing truth values of signals in each part of the circuit of the present invention, and FIGS. Figure 5 is a block diagram of the circuit previously proposed by the applicant, Figure 6 is a diagram showing the truth values of the signals of the circuit shown in Figure 5, Figure 7 is a diagram showing the vertical direction of the screen. FIG. 8 is a specific circuit diagram of MAX and MIN. 1... Composite video signal input terminal, 4... Color signal output] terminal, 8... Luminance signal output terminal, 50...
Broadband [filter, 51, 70-11-1f extension [i]
ffi, 52・-55,72,75...High potential detection circuit (MΔX), 56-59,73,7/Il...Low potential detection circuit (MIN), to 60・63,76.78・・
・Adder, 64.68°77...Subtractor, 65 narrowband degree filter, 66°67...Delay circuit, 71,7
9,80.81...Inverter. Patent applicant: Japan Victor Co., Ltd. Agent: Patent attorney: Tadashi Ito Production volume: Patent attorney: Kaneyuki Matsuura

Claims (1)

[Claims] A wideband filter that separates a composite video signal to obtain a color signal; Previous signal and 2N
a first circuit for detecting a signal in the case of a picture pattern in which the hue is reversed in the vertical direction of the screen from the output of the broadband filter, the signal before the N lines, and the signal before the 2N lines; An arithmetic circuit detects whether there is a vertical correlation with the color signal or not from the output of the broadband filter, the signal before the N lines, and the output of the first arithmetic circuit, and detects whether there is a vertical correlation or not. If there is no vertical correlation, the color signal is extracted with a wideband characteristic; if there is no vertical correlation, the color signal is extracted with a narrowband characteristic; 1. A video signal processing circuit comprising: a second arithmetic circuit that extracts a luminance signal as "1" and a luminance signal as "0".