JPH02228190A - Composite television signal generating circuit - Google Patents

Abstract

PURPOSE:To generate a picture free from the degradation in quality by providing a first band limiting device which limits the band of a luminance signal in accordance with the motion and a second band limiting device which limits the band of a color signal in accordance with the motion and performing the frequency multiplexing of the luminance signal and the color signal outputted from both band limiting devices. CONSTITUTION:At the time of a moving picture, a mixture ratio of mixer circuits 39 and 46 is changed in accordance with larger one of extends of motion detected by motion detecting circuits 40 and 44 to weight a component for moving picture. Therefore, the luminance signal component has the band limited by a BPF 36, and the frequency area is extended in the direction of the time base but is not extended in the vertical direction. Consequently, the luminance signal and the color signal are separated without crosstalk by processing adapted to the motion. At the time of a still picture, the band is limited by LPFs 13, 14, and 45, and the mixture ratio of mixing circuits 39 and 46 is changed in accordance with larger one of extents of motion detected by motion detecting circuits 40 and 44 to weight a still picture component. The composite TV signal is extended in the vertical direction but is not extended in the direction of the time base, and the luminance signal and the color signal are completely separated with a specific frequency in the direction of the time base.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention provides a composite television signal by multiplexing a luminance signal and a color signal or additional signals according to the movement of a television image. The present invention relates to a composite television signal generation circuit that generates a composite television signal.

(Prior Art) Current color television systems use a composite television signal in which a luminance signal is superimposed on a color subcarrier (chromaticity signal) modulated by a color signal.

For example, the NTSC system is shown on pages 132 to 141 of Broadcasting System (Japan Broadcasting Corporation, published January 20, 1980). FIG. 10 shows a television signal transmission and reception system based on the NTSC system disclosed in this document.

In FIG. 10, 10 is an NTSC encoder on the transmitting side, and R (red) is supplied from a signal source (not shown) such as a camera or VTR supplied to this encoder 10.

Each G (green) and B (blue) video signal is sent to the matrix circuit 1.
1 for luminance signal Y and color signal 1. It is converted to Q. Of these, the Y signal is directly supplied to the adder circuit (Σ) 12. In addition, I and Q signals are passed through a low pass filter (L P F) 1
After being band-limited in step 3.14, each signal is orthogonally modulated by a carrier signal (frequency is fsc) from the carrier generation circuit 17 in multipliers 15 and 16, and becomes a chromaticity signal. Each chromaticity signal is supplied to an adder circuit 12 where it is added with the Y signal to form a composite television set signal.

On the other hand, 18 is an NTSC decoder on the receiving side, and the composite television signal from the encoder 1O supplied to this decoder 1B is processed by a Y/C separation circuit 19 into a Y signal and a C signal (I signal and Q signal are orthogonally modulated. color signals). The separated Y signal is directly supplied to the inverse matrix circuit 20, and the C signal is demodulated into I and Q signals by a multiplier 21.22 and a carrier generation circuit 23, and after band-limiting by low-pass filters 24.25, respectively. , are supplied to the inverse matrix circuit 20. This inverse matrix circuit 20 converts the Y, I, and Q signals into the original video signals R, G.
, B and output to a monitor (not shown), for example.

As mentioned above, color television signals based on the conventional NTSC system multiplex luminance signals and color signals on the transmitting side, so luminance/color (hereinafter referred to as Y/C) separation processing is required on the receiving side. be. However, if this processing is performed simply, image quality deterioration such as cross-color dot crawling occurs due to incomplete separation. Recently, there has been a trend to use comb filters with good separation performance for Y/C separation processing.
Even so, the resolution in the diagonal direction is not sufficient.

In order to improve these problems, in recent years, a Y/C separation circuit has been developed that detects movement information of a pattern and changes parameters of filter characteristics.

The configuration of this circuit is, for example, SMPTE Journal (19
As described on pages 470 to 476 of the May 1984 publication, for high-definition television signal processing,
A motion detection signal is generated for a still image by interframe computation, and Y/C separation is performed in correspondence with this motion detection signal. FIG. 11 shows the configuration of a Y/C separation circuit according to the literature.

In FIG. 11, the composite television signal supplied to the input terminal 2B is supplied to a subtracter 27, an interline arithmetic unit 28, an interframe arithmetic unit 29, and a motion detector 30. The inter-line arithmetic unit 28 and the inter-frame arithmetic unit 29 sequentially calculate difference components between lines and frames from the input composite television signal, respectively, and the outputs of each arithmetic unit 28 and 29 are outputted to the gain control circuit 31°. Adder 3 via 32
2a and synthesized.

The composite output obtained here is led out from the output terminal 34 as the color signal C via the horizontal band filter 33 and is also supplied to the subtracter 27. In other words, this subtractor 2
7 subtracts the color signal C from the composite television signal to extract the luminance signal Y, and this luminance signal Y is sent to the output terminal 3.
5. On the other hand, the motion detector 30 detects the amount of motion corresponding to the motion of the image from the input composite television signal, generates a control signal according to the amount of motion, and controls the gain of the gain control circuits 31 and 32. It is something to control.

In other words, when a composite television signal is stationary between frames, each frequency component of the luminance signal component 'Is and the chromaticity signal component C1 spreads in the vertical direction, as shown in FIG. 12(a). , since it does not spread in the time direction,
The chromaticity signal Cl can be separated by calculation between frames. Conversely, when a composite television signal moves between frames, the frequency components of the luminance signal component yl and the chromaticity signal component c1 change in the vertical direction, as shown in FIG. 12(b). Since the chromaticity signal C1 is spread out in the time direction without being spread out, the chromaticity signal C1 can be separated by calculation between lines. Therefore, in the above Y/C separation circuit, the gain of the gain control circuit 32 is increased and the gain of the gain control circuit 31 is decreased for still images, and for moving images, the control is reversed to that for still images. I have to.

By the way, the Y/C separation circuit with the above configuration performs separation processing while adapting to the movement of the image, so it can achieve good Y/C separation.
It should be possible to obtain separation characteristics, but this method assumes that the spectrum does not spread in the vertical direction when moving images, and in actual television images, due to the high performance of TV cameras, etc., the spectrum does not spread in the vertical direction even when moving images. Since the spectral spread in the vertical direction is large, there is a problem in that crosstalk occurs due to the spectral spread in the vertical direction when moving images.

On the other hand, in recent years, EDT V has been developed which further improves the image quality of the conventional NTSC television signal mentioned above.
(Extended Definition TV
) method is being developed. 1 of this EDTV method
One candidate is the wide aspect TV system, which multiplexes additional information for expanding the aspect ratio onto the diagonal high frequency portion of the television signal, making it compatible with current receivers.

Regarding this method, for example, see the Technical Report of the Television Society (published August 1988, Vol.

12), pages 55 to 60. The additional information multiplexed spectrum according to this document is shown in FIG.

That is, FIG. 13(a) shows each region in the horizontal and vertical directions when the main signal (luminance signal) and multiplexed signal (additional signal) are multiplexed, and FIG. 13(b) shows the regions in the time direction and the vertical direction. Each area is shown in the vertical direction. This takes advantage of the fact that the diagonal high-frequency component of the luminance signal has a low visual contribution and is used as a multiplexed region. However, if a television signal in which additional signals are multiplexed in a wide diagonal area is encoded into an NTSC composite television signal, the crosstalk between the Y and C signals that occurs during Y/C separation as described above can be avoided. In addition, crosstalk of multiplexed signals also occurs, which is not preferable in principle.

(Problem 8 to be solved by the invention) As described above, in the conventional motion adaptive Y/C separation circuit, when separating an NTSC television signal into a Y signal and a C signal, This results in signal crosstalk. Further, when additional information is multiplexed in the diagonal high frequency range of the luminance signal, crosstalk of the multiplexed signal further occurs.

This invention was made to solve the above problems, and it is possible to perform Y/C separation that accurately adapts to motion even in moving images without causing image quality deterioration. An object of the present invention is to provide a composite television signal generation circuit that can prevent crosstalk from occurring during separation even when multiplexed.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a composite television signal generation circuit according to the present invention provides: (1) multiplexing a luminance signal and a color signal to generate a composite television signal; A motion detecting means for detecting and outputting each motion amount of the luminance signal and color signal, and a selection for selecting and outputting the larger one of the motion amounts of the luminance signal and color signal obtained by this means. means, extracting from the luminance signal a component higher than the horizontal boundary frequency with the color signal, and extracting from the component a component lower than the vertical boundary frequency with the color signal,
Both components are mixed at a weighting ratio determined according to the amount of movement obtained by the selection means, and a component lower than the horizontal boundary frequency with the color signal is added to this mixed output to adjust the luminance according to the movement. a first band-limiting means for band-limiting a signal; extracting a component equal to or less than the difference between the color subcarrier frequency and the horizontal boundary frequency from the color signal; A component having a difference from the frequency or less is extracted, and this component and the current color signal are mixed at a weighting ratio determined according to the amount of motion obtained by the selection means, and then orthogonally modulated with a color subcarrier to produce a motion signal. a second band-limiting means for band-limiting the color signal accordingly; and a multiplexing means for frequency-multiplexing the luminance signal and the color signal output from the first and second band-limiting means to generate a composite television signal. The first feature is that it has the following.

(2) In a device that generates a composite television signal by multiplexing a luminance signal, a chrominance signal, and an additional signal, a component having a frequency equal to or higher than the horizontal boundary frequency with the additional signal is extracted from the luminance signal, and the component is combined with the additional signal from the component. third band limiting means for band-limiting the luminance signal by determining a component below the boundary frequency in the vertical direction and the temporal direction of the luminance signal, and adding this component to a component below the boundary frequency in the horizontal direction of the additional signal; a first multiplexing means for frequency multiplexing an additional signal in the band-limited frequency domain of the luminance signal obtained by this means; and a motion detection means for detecting the amount of movement of each of the luminance signal and color signal obtained by this means. a selection means for selectively outputting the larger of the amounts of movement of the luminance signal and color signal obtained by this means; and a horizontal boundary between the luminance signal and the color signal obtained by the first multiplexing means. A component above the frequency is extracted, a component below the boundary frequency in the vertical direction with the color signal is extracted from the component, and both components are mixed at a weighting ratio determined according to the amount of motion obtained by the selection means. a first band-limiting means for band-limiting the luminance signal according to movement by adding a component below the boundary frequency in the horizontal direction with the color signal to the mixed output; extracting a component that is less than or equal to the difference between the boundary frequency of the color subcarrier frequency and the boundary frequency in the vertical direction; a second band-limiting means for band-limiting the color signal according to motion by orthogonally modulating the color signal after mixing at a determined weighting ratio; and output from the first and second band-limiting means. A second feature is that the apparatus includes a second multiplexing means for frequency multiplexing the luminance signal and the color signal to generate a composite television signal.

(Function) In the case of (1), the composite television signal generation circuit with the above configuration detects the amount of movement of the luminance signal and the color signal and selects and outputs the larger one, while the amount of movement of the luminance signal and the color signal is detected. The components above the horizontal boundary frequency are band-limited to below the vertical boundary frequency according to the amount of movement, and on the other hand, the color signal is divided into a color subcarrier frequency and the horizontal boundary frequency according to the amount of movement. The color signal is band-limited to a component that is less than or equal to the difference between the color subcarrier frequency and the vertical boundary frequency, and then orthogonally modulated with the color subcarrier, and the color signal is frequency multiplexed to the band-limited region of the luminance signal. to generate a composite television signal. According to this, since neither the luminance signal nor the chrominance signal of the composite television signal for moving images spreads in the vertical direction, it becomes possible to separate the signals at a specific vertical frequency without causing crosstalk.

In the case of (2), the components of the luminance signal that are higher than the boundary frequency in the horizontal direction and lower than the boundary frequency in the vertical and temporal directions with the additional signal are band-limited, and the additional signal is frequency-multiplexed in the band-limited area. , detects the amount of movement of each of the multiplexed luminance signal and chrominance signal of this additional signal and selects and outputs the larger one, while the components of the luminance signal that are higher than the horizontal boundary frequency with the chrominance signal are The band is limited to below the boundary frequency in the vertical direction depending on the amount of movement, and on the other hand, the color signal is limited to below the difference between the color subcarrier frequency and the boundary frequency in the horizontal direction, depending on the amount of movement, and the color subcarrier frequency and the boundary frequency in the vertical direction are limited depending on the amount of movement. A composite television signal is generated by band-limiting the component to a component that is less than or equal to the difference from the boundary frequency of the luminance signal, then orthogonally modulating it with a color subcarrier, and frequency-multiplexing the color signal onto the band-limited region of the luminance signal. According to this, the composite television signal during moving images is an additional signal,
Since neither the luminance signal nor the chrominance signal spreads in the vertical direction, they can be separated without causing crosstalk at a specific vertical frequency.

Both (1) and (2) band-limit the vertical high-frequency components of the luminance signal, but since human visual characteristics have low sensitivity to the resolution of moving images, the image quality deterioration during moving images is almost negligible. .

(Example) Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 9.

FIG. 1 shows a configuration in which the present invention is applied to an NTSC encoder and a composite television signal is generated by adapting a luminance signal and a color signal to the movement of an image. However, in FIG. 1, the same parts as those in the circuit of FIG. 10 are denoted by the same reference numerals, and their explanation will be omitted here.

First, R and G output from a signal source such as a camera or VTR
, B are converted into Y, I by the matrix circuit 11.
, is converted into a Q signal. Of these, the Y signal is supplied to a low pass filter (LPF) 3B and a subtracter 37. The cutoff frequency of the low-pass filter 3B is 3,0 [M
Hzl, and the subtracter 37 outputs 3 and 0.
[Components of MHz 1 or higher are output.

This frequency signal of 3.0 [MHz] or higher is supplied to a vertical low-pass filter (vertical LPF) 38.

The cutoff frequency of this vertical low-pass filter 38 is selected to be 525/8 [cphl, and its output signal is sent to the first mixer circuit (MIX
)39.

On the other hand, the Y signal output from the matrix circuit 11 is
At the same time, the signal is also supplied to the first motion detection circuit 40. This first motion detection circuit 40 calculates the difference component between one frame of the Y signal and generates a motion detection signal indicating the amount of motion from the calculation result. (MAX: Output the larger of the two manual forces) 41 to the first mixer circuit 39 (and a second mixer circuit (MIX) 4B to be described later). This mixer circuit 3
9, when it is determined that it is a moving image from the motion detection signal, the weight of the output signal of the vertical low-pass filter 38 is increased according to the amount of motion, and when it is determined that it is a still image, the weight of the output of the subtractor 37 is increased. It is something to do. This first mixer circuit 3
The output of 9 is sent to the adder 4 along with the output of the low-pass filter 36.
2 and is added and synthesized here to adder circuit (Σ)1.
2.

Also, I output from the matrix circuit 11.

The Q signal is band-limited by low-pass filters 13 and 14, and then time-division multiplexed by selector 43.

The I and Q multiplexed signals output from this selector 43 are
motion detection circuit 44, low pass filter (LPF) 45
, are supplied to the second mixer circuit 46.

The second motion detection circuit 44 calculates the difference component between one frame from the I, Q multiplexed signal, and generates a motion detection signal indicating the amount of motion from the calculation result. The second mixer circuit 46 (
and the aforementioned first mixer circuit 39). The maximum value selection circuit 41 receives the motion detection output of the Y signal and 1.
It compares the motion detection output of the Q multiplexed signal and selects and outputs the maximum value, and the output signal is used to control the mixing ratio in the first and second mixer circuits 39 and 46.

Only the low-frequency components of the I and Q multiplexed signals inputted to the low-pass filter 45 are extracted, and after being band-limited by the vertical low-pass filter (vertical LPF) 47,
The signal is supplied to the second mixer circuit 4B. As in the case of the Y signal, this second mixer circuit 46 increases the weighting of the 1 and Q multiplexed signals band-limited by the low-pass filter 45 and the vertical low-pass filter 47 in the case of moving images, and in the case of still images. is the non-bandwidth l output from the selector 43.

The weight of the Q multiplexed signal is increased and both are mixed and output. Note that the cutoff frequency of the low-pass filter 45 is selected to be 0.5 [MIIz], and the cutoff frequency of the vertical low-pass filter 47 is selected to be 525/8 [cphl].

The I and Q multiplexed signals outputted from the second mixer circuit 4B are separated into an I signal and a Q signal by a separation circuit 48. Then, in multipliers 15 and 16, the carrier signals from the carrier generation circuit 17 (the frequency is balanced modulated by tsc) are supplied to the adder circuit 12, where they are added with the Y signal to form a composite television signal, and the output terminal 4
9 as the encoder output.

In the above configuration, the operation thereof will be described below with reference to FIGS. 2 and 3 showing spectra during a moving image and a still image, respectively. In addition, in Figures 2 and 3, (a)
The figure shows (b
) The figure shows the frequency domain in the time direction and the vertical direction at the same horizontal frequency a in figure (a).

First, a horizontal component of 3,0[MIIz1 or more is extracted from the current Y signal by the low-pass filter 3B and the subtracter 37, and inputted to the first mixer circuit 39 for still images, and is input to the first mixer circuit 39 by the vertical low-pass filter 3&. 3
A vertical component of 525/8 [cph] or less is extracted from the output of 7 and sent to the first mixer circuit 39 for video use.
Enter. After performing the motion adaptive processing here, the adder 42 receives 3, O[MII
It is added to the horizontal frequency component below zl and input to the adder circuit 12.

On the other hand, I output from the selector 43.

The Q multiplexed signal is input to the second mixer circuit 4B for still images, and a low pass filter 45 extracts horizontal components of 0.5 [MHz] or less from the 1 and Q multiplexed signals, and a vertical low pass filter 47 extracts the horizontal components. A vertical component of 525/8 [cph] or less is extracted and input to the second mixer circuit 4B for use in a moving image. After performing motion adaptation processing here, the separation circuit 48
．． The signal is separated into a Q signal, quadrature modulated by a carrier signal in mixers 15 and 18, inputted to an adder circuit 12, and added to the Y signal to generate a composite television signal.

Here, if the direct placement is a moving image, the first
The mixing ratio of the second mixer circuits 39 and 46 changes, and weighting is applied to the moving image component. Therefore, the composite television signal is 3,0 [M
Hz] or higher luminance signal component is 525/8 [cph
], and the color signal component is band-limited to the carrier frequency f
, c' -3,58 [MHz] horizontally ±0, 5 [MHz] vertically ±525 /
8 [Bandwidth will be limited to the range of cphl.

At this time, if we look at the frequency region of the composite television signal in the time direction and the vertical direction above 3.0 [MHz], as shown in Figure 21(b), although it spreads in the time direction, it also spreads in the vertical direction. vertical frequency 5
25/8 [Completely separated in cphl. Therefore, even if the composite television signal obtained by this encoder is input to the conventional Y/C separation circuit shown in Fig. 11 and subjected to motion adaptive processing to perform Y/C separation, no crosstalk will occur. Luminance signals and color signals can be separated. In this case, the diagonal high-frequency components of the luminance signal decrease, but
Since the human visual angle is slow to movements, the appearance is good and there is no effect on the corridor.

On the other hand, if it is a still image, the mixing ratio of the first and second mixer circuits 39.46 changes according to the larger value of the amount of motion detected by the motion detection circuits 40.44. Weight is applied to the ingredients. Therefore, in the composite television signal, as shown in FIG. 3(a), the luminance signal component of 3.0 [MH2] or more is not band-limited, and the color signal component is not band-limited either. At this time, 3 of the composite television signal
, 0 [NHZ] or more in the time and vertical directions.As shown in Figure 3(b), although it spreads in the vertical direction, it does not spread in the time direction, and only at a specific time. Completely separated in directional frequency. Therefore, even with the conventional Y/C separation circuit shown in FIG. 11, the luminance signal and color signal can be separated without causing crosstalk.

Therefore, the NTSC encoder configured as described above generates a composite television signal by band-limiting the luminance signal and chrominance signal so that the spectrum does not spread in the vertical direction during moving images, so the luminance signal is Even when separating into chrominance and chrominance signals, no crosstalk occurs between the luminance signal and chrominance signal.

Therefore, Y/C separation that accurately adapts to motion is possible without deteriorating image quality.

FIG. 4 shows another embodiment of the present invention, and this circuit is constructed in the embodiment of FIG. 1 so that an additional signal is multiplexed into the oblique high frequency range of the luminance signal. In FIG. 4, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

First, the Y signal output from the matrix circuit 11 is
A low-pass filter 50 and a subtracter 51 are manually inputted. The low-pass filter 50 has a cutoff frequency of 2 and 0.
[MHz] is selected, and 2 from the input Y signal.
, 0 [MHz] or lower, and subtracter 5
1 and the adder 52. The Y signal supplied to the subtracter 5I has its low frequency components below 2,0[MHzl] subtracted, and is supplied to the vertical-temporal filter 53 as only the high frequency components above 2,0[MIIz1. This vertical-temporal filter 53 converts the vertical components of the input signal into 52
5 x 3 / 8 [cph] or less, and the temporal component is limited to ±15 [Hz] or less, and its output is combined with the low-frequency component from the low-pass filter 50 in an adder 52 . Although the diagonal high frequency components are removed from the Y signal through the above processing, an additional signal is multiplexed into this region by the adder 54. The following is the same as in the case of M1 diagram.

A specific configuration of the vertical-temporal filter 53 is shown in FIG. Although a configuration with seven taps is shown here as an example, it is also possible to increase the number of taps by adding hardware.

The vertical-time filter shown in FIG.
．． 110-62 and field memory (259H) 59
A predetermined pixel is taken out and sent to the first weighted sum circuit B3.
, -1, -2, -262, -263° -264, -26
Send 7 line pixels of 5,'! O, -1, -2, -3° -263, -264, -265 to N2 weighted sum circuit B4
7 lines of pixels are sent, and calculations are performed in the vertical direction for each. Then, the output of the first weighted sum circuit B3 is sent one field to the field memory (263H) 65, and is input to the selector 6B together with the output of the second weighted sum circuit 64. The fields are output from the output terminal B7 in order.

That is, the first weighted sum circuit 83 performs a weighted sum operation on the line pixels from -262 to -265 in the first field and the line pixels from 0 to -2 in the second field, as shown in FIG. 6(a). By doing this, the value of the -1 line pixel in the second field, which is the main tap, is obtained. The output of the first weighted sum circuit B3 is the value of the second field as shown in FIG. 6(b), and the field memory 65 stores that value up to the third field as shown in FIG. 6(c). 'It's delayed.

On the other hand, in the second weighted sum circuit 64, as shown in FIG. By doing this, the value of the -264th line pixel in the first field, which is the main tap, is obtained. Since the output of the second weighted sum circuit 84 is the value of the second field as shown in FIG. 6(e), the selector 8B selects the first field, second field, . By outputting it, it is possible to reduce vertical high-frequency components that occur during moving images.

For example, as shown in FIG. 7(a), when a black object moves horizontally against a white background, a difference in brightness occurs between the first field and the second field, and a vertical high-frequency component is generated. According to the vertical-temporal filter, since the first field and the second field are calculated simultaneously, vertical high frequency components can be reduced as shown in FIG.

FIG. 8 shows the spectrum of the moving image in the embodiment shown in FIG. 4, and FIG. 9 shows the spectrum of the still image.

8 and 9, (a) shows the frequency domain in the horizontal direction and the vertical direction, and Fig. (b) shows the frequency domain in the time direction and the vertical direction at the horizontal frequency a in the figure (a). It shows.

As is clear from Fig. 8, this encoder has multiplexed signals in the vertical high range (3x525/8 to 525/2 [cphl) and horizontal high range (2.0 to 4.2 (MIIzl)). Since the additional signal is band-limited in the same way as in the embodiment shown in FIG.
The luminance signal and color signal are separated, and 525 x 3 /
8 [Since the color signal and the additional signal are separated by cphl, the decoder side can easily separate and process each signal using these thresholds. On the other hand, in the case of a still image, as shown in Fig. 9, although it spreads in the vertical direction, the color signal and luminance signal are separated at a specific frequency in the time direction, and the vertical frequency is 525 x 3/8 [cphl]. Since the luminance signal and the additional signal are separated, the decoder side can easily separate and process each signal using these thresholds.

Therefore, if this invention is applied to an encoder that generates a composite television signal, it will adapt to motion, and in the case of a moving image, the luminance signal will be reduced to 3.0 [MHz1 or higher components to 525/8 [cphl or lower]. , the color signal is horizontally 0. 5 [MHz], vertical 525/8 [cp
H] or less, it is possible to perform complete Y/C separation without deteriorating image quality on the decoder side, and even if additional signals are multiplexed in the diagonal high frequency range by similar processing, the decoder side can perform complete Y/C separation without deteriorating image quality. Additional signals can be separated without causing crosstalk.

[Effects of the Invention] As described above, according to the present invention, the Y/
It is possible to provide a composite television signal generation circuit that is capable of C separation and that can prevent crosstalk from occurring during separation even when additional signals are multiplexed in diagonal high frequencies.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of a composite television signal generation circuit according to the present invention, FIG. 2 is a diagram showing a composite television signal spectrum during a moving image in the embodiment of FIG. 1, and FIG. 1 is a diagram showing a composite television signal spectrum during a still image in the embodiment of FIG. 1, FIG. 4 is a block circuit diagram when an additional signal multiplexing function is added to the embodiment of FIG. 1, and FIG. FIG. 4 is a block circuit diagram showing a specific configuration of the vertical-temporal filter of the embodiment, FIG. 6 is a diagram for explaining the operation of the vertical-temporal filter of FIG. 5, and FIG. 7 is the diagram shown in FIG. FIG. 8 is a diagram showing a composite television signal spectrum during a moving image in the embodiment of FIG. 4, and FIG. 9 is a diagram showing a composite television signal spectrum of the embodiment of FIG. FIG. 10 is a block circuit diagram showing the configuration of an encoder and decoder in the conventional NTSC system. FIG. 11 is a diagram showing the configuration of a conventional motion adaptive Y/C separation circuit. FIG. 12 is a diagram for explaining the operating principle of the circuit in FIG. 11, and FIG. 13 is a diagram for explaining conventional means for multiplexing an additional signal onto a composite television signal. IO...NTSC encoder, ll...Matrix circuit, 12...Addition circuit, 13.14...Low pass filter, 15, 16...Mixer, 17...Carrier generation circuit, 18...・NTSC decoder, 19...
・Y/C separation circuit, 2o... inverse matrix circuit, 2
1.22...Mixer, 24.25...Low pass filter, 2B...Composite television signal input terminal, 27
...Subtractor, 28...Line-to-line arithmetic unit, 29...
Interframe arithmetic unit, 30...Motion detector, 31.32
...Gain control circuit, 33...Horizontal band filter, 3
4... Color signal output terminal, 35... Luminance signal output terminal, 3B... Low pass filter, 37... Subtractor, 3
8... Vertical low-pass filter, 39... First mixer circuit, 40... Motion detection circuit, 41... Maximum value selection circuit, 42... Adder, 43... Selector,
44...Motion detection circuit, 45...Low pass filter, 47...Vertical direction low pass filter, 4B...Second mixer circuit, 48...I, Q separation circuit, 49...
- Composite television signal output terminal, 50...Low pass filter, 51...Subtractor, 52...Adder, 53
...Vertical-temporal filter, 54...Adder, 56-
58. Go~62...1 line delay device, 59...
Field memory, 63.84... Weighted sum circuit, 65
...Field memory, 6B...Selector, 67.
...Additional signal multiplex output terminal. Applicant's agent Patent attorney Takehiko Suzue Figure 7 10 (b) Figure 13

Claims (2)

[Claims] (1) In a composite television signal generation circuit that multiplexes a luminance signal and a chrominance signal to generate a composite television signal, a motion detection means detects the amount of movement of each of the luminance signal and the chrominance signal; a selection means for selecting and outputting the larger one of the moving amounts of the luminance signal and the color signal, and extracting a component having a horizontal boundary frequency or higher with respect to the color signal from the luminance signal; A component below the boundary frequency in the horizontal direction is extracted, and both components are mixed at a weighting ratio determined according to the amount of motion obtained by the selection means, and this mixed output is given a component below the boundary frequency in the horizontal direction with the color signal. a first band-limiting means for band-limiting the luminance signal according to motion; and extracting a component equal to or less than the difference between the color subcarrier frequency and the horizontal boundary frequency from the color signal; A component that is less than or equal to the difference between the color subcarrier frequency and the vertical boundary frequency is extracted, and this component and the current color signal are mixed at a weighting ratio determined according to the amount of motion obtained by the selection means, and then the color is a second band limiting means for performing orthogonal modulation with a subcarrier and band limiting the color signal according to movement; and frequency multiplexing of the luminance signal and the color signal output from the first and second band limiting means. 1. A composite television signal generation circuit comprising: multiplexing means for generating a composite television signal. (2) In a composite television signal generation circuit that generates a composite television signal by multiplexing a luminance signal, a chrominance signal, and an additional signal, a component having a horizontal boundary frequency or higher with respect to the additional signal is extracted from the luminance signal, and A third band for band-limiting the luminance signal by extracting a component below the boundary frequency in the vertical and temporal directions with the additional signal from the component, and adding this component and a component below the horizontal boundary frequency with the additional signal. a limiting means, a first multiplexing means for frequency multiplexing an additional signal in the band-limited frequency domain of the luminance signal obtained by this means, and detecting the amount of movement of each of the luminance signal and color signal obtained by this means. a selection means for selecting and outputting the larger of the amounts of movement of the luminance signal and color signal obtained by the means; A component having a horizontal boundary frequency or higher is extracted, a component having a vertical boundary frequency or lower with respect to the color signal is extracted from the component, and both components are weighted at a weighting ratio determined according to the amount of motion obtained by the selection means. a first band limiting means for band-limiting the luminance signal according to movement by adding a component below the horizontal boundary frequency with the color signal to the mixed output; and the horizontal boundary frequency, extract a component that is equal to or less than the difference between the color subcarrier frequency and the vertical boundary frequency, and combine both components with the motion obtained by the selection means. a second band limiting means for band-limiting the color signal according to the movement by orthogonally modulating the color signal with a color subcarrier after mixing at a weighting ratio determined according to the amount;
and second multiplexing means for frequency multiplexing the luminance signal and color signal output from the band limiting means to generate a composite television signal.