JPS61156994A - Processing circuit of video signal - Google Patents

Abstract

PURPOSE:To effectively control a Y/C separating circuit or the like adapted to a movement by supplying a color video signal to a filter for passing only a side band composition produced by the movement and surely detecting a moving composition. CONSTITUTION:The spectrum of the still section of an image has a brightness signal Y and chrominance components C which become a luminous line spectrum and has no side band composition. In the movement section of the image, since there is a change in a time direction T, a carrier is modulated by the movement to be a continuous spectrum having the side band composition. A filter 100N comprised of multipliers 16, 19, an adder 17, a delay line 18 and a subtracter 20 checks a carrier composition at every 15Hz and has a characteristic for passing the side band composition produced by the movement. As the output of the subtracter 20, a movement composition including no brightness signal and the chrominance components (still composition) is obtained. Thereby, the movement composition is surely detected. The controls of a Y/C separating circuit adapted to the movement in a processing circuit 13 and a successively scanning converting circuit can be effectively carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal processing circuit suitable for detecting a motion component from a color video signal of the NTSC system or FAI system, for example.

[Conventional technology]

In order to detect a motion component from a video signal, a frame difference signal may be obtained. However, for example, NTSC
In the video signal of this method, the phase of the color signal is reversed for each frame, so this frame difference signal includes the color signal (
(stationary component) also appears. Therefore, it has been proposed to remove the color signal contained in this frame difference signal using a low-pass filter. FIG. 9 shows an example of this, in which the video signal SvN is directly supplied to the subtracter (1), and is also supplied to the subtracter (1) via a delay line (2) having a delay time of one frame.
1). The output of this subtracter (1) is then supplied to a low-pass filter (3), and the output of this low-pass filter (3) is taken as the motion component SM. However, when the one-frame difference signal is passed through the low-pass filter (3) as shown in the example in Figure 9, even high-frequency motion components are removed, and even if the brightness is equal and only the color moves, this is detected. There is a drawback that it cannot be done.

Therefore, conventionally, a chroma inverter is used to invert the part that is considered to be the color signal and then obtain a one-frame difference signal.
It has been proposed to prevent color signals (static components) from appearing in this one-frame difference signal. FIG. 10 shows an example of this, where the video signal SVN is supplied to a subtracter (4).

Further, the video signal SvN is supplied to a chroma inverter (6) via a delay line (5) having a delay time of one frame, and after only the color signal is inverted by this chroma inverter (6), it is sent to a subtracter (4). supplied to The output of this subtracter (4) is then taken as the motion component SM. However, in the case where the color signal is inverted by the chroma inverter (6) as shown in the example in FIG.
In principle, it is impossible to obtain a perfect luminance signal/chrominance signal separation circuit used in In addition to the motion component, there is a luminance signal that was originally in the same phase (
The disadvantage is that a stationary component) appears.

[Problem that the invention seeks to solve]

As described above, with the conventionally proposed method using a one-frame delay line, motion component detection was not perfect.

In view of this point, the present invention enables motion components to be detected more accurately.

[Means for solving problems]

The spectrum in the time direction T in the still part of the image is a bright line spectrum and does not have sideband components, whereas in the moving part of the image, both the luminance signal and the color signal move in the time direction, so the carrier is modulated by the movement. resulting in a continuous spectrum with sideband components.

Therefore, in the present invention, a filter is constructed that passes only the sideband components caused by the above-mentioned motion, and a color video signal is supplied to this filter, so that the motion component is obtained as an output.

That is, the present invention weights an input color video signal by (1-K) (where 0≦K≦1) and supplies it to an adder.
The output of this adder is supplied to a delay line having a delay time of 2 or 4 frames, and the output of this delay line is weighted by K and supplied to the adder to constitute a recursive filter. The signal and the output of the adder or the output of the delay line are supplied to a subtracter, and the motion component of the color video signal is obtained as the output of the subtracter. Here, if the input color video signal is in the NTSC format, the delay line has a delay time of 27 frames, and if the input color video signal is in the PAL format, the delay line has a delay time of 4 frames.

[Effect]

In the above configuration, only sideband components caused by motion are detected as motion components.

In other words, motion components are detected more reliably.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIG.

In the figure, (7) is an antenna, αη is a tuner, and the tuner α outputs an NTSC color video signal Sv (525 lines/frame, 60 fields/second, interlace ratio 2:1). can get. This video signal SvN is converted into a digital signal by the ω converter α2, and then supplied to the brightness/color processing circuit (b).

This processing circuit αJ separates luminance signals and color signals (Y/C
Separation), color demodulation, progressive scan conversion, masking, IJ processing, etc. are performed. For example, the Y/C separation circuit and the progressive scan conversion circuit are configured to be motion adaptive.

In other words, a motion-adaptive T-separation circuit is one that performs Y/C separation by inter-frame signal processing in a still part of an image, and performs Y/C separation by inter-line signal processing in a moving part of an image. It is something. In addition, a motion-adaptive progressive scan conversion circuit is used, for example, in a still part of an image.
Information from one field before is used as the interpolation signal, and in moving parts of the image, the interpolation signal is synthesized from upper and lower scanning line information in order to prevent blurring of the image.

The red of the progressive scanning method obtained from this processing circuit (to).

The green and blue primary color signals R, G, and B are converted into analog signals by a D/A converter α4, and then supplied to a color picture tube k. A color image is displayed on the picture tube C15 using a progressive scanning method.

Further, the video signal SvN from the φ converter (2) is supplied to the adder αη via a multiplier αQ with a gain of (1−K) (where 0≦K≦1). The output of this adder αη is also supplied to a delay line <11 having a delay time of two frames. The output of this delay line C11m is supplied to the adder αη via a gain multiplier. These multipliers αQ, 09, adder αη, and delay line α barrel constitute a recursive filter.

Further, the video signal SvN is supplied to a subtracter (1), and the output of the adder αη is supplied to this subtracter (A).

The output of this subtracter is supplied to a separation circuit e1) which removes the small amplitude part to remove noise. This separation circuit? The output of D is sent to the coefficient ROM via the Ronos filter (A).
q is converted into an appropriate value in this coefficient ROM (a), and the present example is constructed as described above based on the output of this coefficient ROM (c).

Here, let us consider the spectrum in the time direction (frame direction) T of the NTSC video signal SvN.

In this video signal SvN, color subcarrier frequency 'll
The relationship between e and the horizontal frequency fh is expressed by the following equation.

As can be seen from equation (1), the phase of the color subcarrier is reversed by 180 degrees every frame. Therefore, as shown in FIG. 2A, the spectrum in the time direction T of a still part of one image is a bright line spectrum for both the luminance signal Y and the color signal C, and has no sideband components. On the other hand, in the moving part of the image, both the luminance signal Y and the color signal C are
Since there is a change in the carrier, the carrier is modulated by the movement, and the second
Shown in Figure B.

The result is a continuous spectrum with sideband components.

By the way, in this example, the multipliers an, Q! , an adder αη, a delay line α frame, and a subtracter (100N), whose characteristics change depending on the value of K as shown in FIG. For example, as the value of K approaches 1, the characteristic approaches the characteristic shown by the solid line a in FIG. 3, and as the value of K approaches 0, the characteristic approaches the characteristic already shown by the dashed line in the same figure.

Note that the characteristic indicated by the broken line C in the figure is one in which K has an intermediate value between O and 1. The steepness of the stopband can be changed by changing the magnitude of K, but in this example, K is set to a value close to 1 (0.8 to 0.9), for example.

As is clear from FIGS. 2 and 3, the filter (10
0N) has the characteristic of blocking carrier components every 15 Hz and passing sideband components caused by motion, and the output of the subtracter (4) is a motion signal that does not include a luminance signal or a chrominance signal (stationary component). Component SM* is obtained.

Therefore, according to this example, the motion component can be reliably detected, and the processing circuit (motion adaptive Y/C separation circuit and progressive scan conversion circuit in 13) can be effectively controlled.

In the example in Fig. 1, the output of the adder αη is supplied to the subtractor RH, but as shown in Fig. 4, the output of the delay line a is supplied to the subtractor (E). It may be a supplied configuration. In this case, the characteristics of the filter (100N'), which is composed of a multiplier ← Q, 4, an adder (17), a delay line a, and a subtracter, change as shown in FIG. 5 depending on the value of K. do. For example, as the value of K approaches 1, the characteristic approaches the characteristic shown by the solid line a in FIG. 5, and as the value of K approaches 0, the characteristic approaches the characteristic already shown by the dashed line in the same figure. In addition, the broken line C in the same figure
The characteristic shown by is one in which K has an intermediate value between O and 1. In this case as well, the steepness of the stopband can be changed by changing the filiality of K, for example K can be set to a value close to 1 (0, 8
~0.9).

As is clear from FIGS. 2 and 5, this filter (
100N') also has the characteristic of blocking carrier components every 15 Hz and passing sideband components caused by movement. No motion component S
M* can be obtained. Also, although the example in Figure 1 describes the case of the NTSC system, the video signal SvP of the PAL system (625 lines/7 frames, 50 fields/sec, interlace ratio 2:1)
In order to detect more motion components, the configuration shown in FIG. 6 may be used.

In other words, the delay line α frame having a delay time of 2 frames in FIG.
It was replaced with .

Here, let us consider the spectrum of the PAL video signal Sv in the time direction T. In this video signal SvP, the color subcarrier frequency 18e and the horizontal frequency fh have the following relationship.

As is clear from equation (2), the phase of the color subcarrier shifts by 900 every frame. Therefore, the spectrum in the time direction T of the still part of the image is a bright line spectrum for both the luminance signal Y and the color signal C, as shown in FIG. 7A, and has no sideband components. On the other hand, in the moving part of the image, both the luminance signal Y and the color signal C are
Since there is a change in the carrier, the carrier is modulated by the movement, and the seventh
This results in a continuous spectrum with sideband components as shown in Figure B.

By the way, in the example in Fig. 6, the multiplier α・, (to), the adder α
The characteristics of a filter (1oop) composed of η, a delay line, and a subtracter (1) change as shown in FIG. 8 depending on the value of K. For example, the closer the value of K is to 1, the more
The closer the characteristic shown by the solid line a in the figure approaches, and the closer the value of K is to O, the more
This approaches the characteristics already shown by the dashed-dotted line in the figure.

Note that the characteristic indicated by the broken line C in the figure is one in which K has an intermediate value between O and 1. In this case as well, by changing the size of K,
By changing the steepness of the stopband, the filter (100P) is set to a value close to 1 (0.8 to 0.9), for example. As is clear from Figures 7 and 8, the filter (100P) is 6.25H
It has a characteristic of blocking carrier components for each z and passing site 9 band components caused by movement, and the output of the subtracter (A) is a motion component SM* that does not include a luminance signal or a color signal (stationary component). is obtained.

Therefore, according to the example in FIG. 6, the motion component can be reliably detected from the PAL video signal SvP.

Although detailed explanation is omitted, the PAL video signal Sv
To detect the motion component from P, the delay line a in FIG. 4 may be replaced with a delay line having a delay time of 4 frames.

〔Effect of the invention〕

According to the present invention described above, a color video signal is supplied to a filter that passes only sideband components caused by motion, and the motion component is obtained as an output, and the motion component can be detected reliably. can. Therefore, if the motion components detected by the present invention are used, motion adaptive Y/C
Separation circuits etc. can be controlled effectively.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 and 3 are diagrams for explaining the same, and FIGS. 4 and 6 are block diagrams showing other embodiments of the present invention. , FIG. 5 is a diagram for explaining the example in FIG. 4, FIGS. 7 and 8 are diagrams for explaining the example in FIG. 6, respectively, and FIGS. 9 and 10 respectively show conventional examples. FIG. α and (to) are multipliers, αη is an adder, α and (c) are delay lines, (1) is a subtracter, (100N) and (io
op) is a filter. Figure 2 B Roma l! l Pickled bamboo (Hz) Fig. 3 Tokuai Shuentao class (Hr) Fig. 4 I-bari number (H) Fig. 6゛Fig.

Claims (1)

[Claims] Input color video signal (1-K) (0≦K≦1
) and feed it to an adder, the output of this adder is fed to a delay line having a delay time of 2 or 4 frames, and the output of this delay line is weighted by K and fed to the adder. to form a recursive filter, supply the color video signal and the output of the adder or the output of the delay line to a subtracter, and obtain the motion component of the color video signal as the output of the subtracter. Video signal processing circuit.