JPH0783488B2 - Signal processing circuit - Google Patents

Description

The present invention relates to a signal processing circuit for color television signals, and is particularly suitable for processing signals different from NTSC signals such as VTR and VDP. Signal processing circuit.

[Conventional technology]

There is known a technique for improving the image quality of a current color television signal by signal processing on the receiver side.
For example, there is Achiha et al. 1: “New R & D Trends at Home and Outside”, Journal of Television Society Vol. 36, No. 10 (1982). In this, there is discussed a signal processing device which handles a color television signal in a three-dimensional space-time in which the time axis is added to the spatial coordinates of the vertical axis and the horizontal axis of the screen. A block diagram of this signal processing apparatus is shown in FIG. This signal processing device detects a motion of an image and adaptively performs various filter processes according to the motion amount. As an example of these adaptive filter processes, two filter processes of YC separation and scanning line interpolation will be described in detail below.

First, we describe the adaptive YC separation method.

As an example of a YC separation method for separating a luminance signal and a color signal from a color television signal of the current system, Japanese Patent Laid-Open No. 58-11
As shown in No. 5995, the movement of the subject is detected by the difference between the input and output of the frame memory, and when the movement is small, YC separation (hereinafter referred to as a frame comb filter) is performed by using the frame correlation, and the movement is performed. When is large, there is a YC separation (hereinafter referred to as line comb filter) using vertical correlation.

The YC separation method in the above conventional example can be expressed as shown in FIG. 3, for example. In this block diagram, the flow of video signals is shown by solid lines, and the flow of control signals is shown by broken lines.

The frame comb filter 305 multiplies the input signal and the output signal of the 1-frame memory 302 by 1/2 with a coefficient unit and takes the difference between them, and the output from the subtractor is a bandpass filter (hereinafter referred to as BPF). It is configured to supply the mixer 310 via 308.

The output of the 1-frame memory 302 is supplied to the BPF 308 via the line comb filter 305, and the output is supplied to the mixer 3
Supplied to 10. In this mixer 310, the color signal C _F separated by the frame comb filter 305 in the case of a still image and the line comb filter in the case of a moving image are controlled by the control signal K.
The color signal C _L separated by 304 is output. This control signal K is obtained in the motion detection and control circuit 303 from the input signal and output signal of the 1-frame memory 302, and the mixer 3
Supplied to 10. The luminance signal Y312 is obtained by subtracting the color signal C output from the mixer 310 from the output signal of the one-frame memory 302 from the signal delayed by the delay circuit 306 by the subtracter 311.

Next, the adaptive processing of scanning line interpolation, which is an improvement method against deterioration such as line flicker and the appearance of a rough scanning line structure, will be described.

This method avoids the above deterioration by interpolating a scanning line on the receiving side and displaying a video of the signal as a signal for sequential scanning. For example, JP-A-58-2053
In the example seen in Japanese Patent Publication No. 77, motion of an image is detected, and when the motion is small, inter-field interpolation is performed as a still image to create an interpolated scan line. Motion adaptive processing such as interpolation is performed. The outline of this signal processing circuit will be described with reference to FIG.

In FIG. 4, 401 is an input terminal, 402 and 403 are first and second field memories, 404 is a scanning line interpolation circuit, 405 is a motion detection circuit, 406 and 407 are first and second time compression circuits, and 408 is a selection circuit. , 409 are output terminals.

The 2: 1 interlaced scanning signal from the input terminal 401 and the signal delayed by one frame period are input to the motion detection circuit 405, and the motion of the image is detected by calculating the absolute value of the inter-frame difference signal. There is. As described above, the characteristics of the scanning line interpolation circuit 404 are controlled by the amount of movement of this image.

Since the input signal is interlaced when creating the interpolated scan line, the scan lines of the fields one field before and one field after the other scan the position of the scan line to be interpolated in the current field. These scanning line signals can be directly used as interpolation scanning line signals. However, such inter-field interpolation can be performed only on a still image. For a moving image, two images that are 1/60 second apart are overlapped, which causes great deterioration.

Therefore, when the amount of motion of the image detected by the motion detection circuit 405 is large and therefore it is determined that the image is a moving image, only the scanning line signal of the current field is used, and for example, two consecutive
The above deterioration is avoided by creating an interpolated scan line signal by averaging the scan lines of the book.

As described above, in the conventional example, the interlaced scan signal is converted into a progressive scan signal without causing deterioration of resolution for still images and deterioration of afterimages even for moving images. can do.

[Problems to be solved by the invention]

As described above, the above-described conventional technique detects that the color signal component is inverted between frames in a still image by performing motion detection and
It is used for YC separation. Therefore, if you try to process the signal reproduced from the current VTR or VDP, the relationship that the color signal component is inverted between frames is lost, so motion detection may malfunction and signal deterioration may occur. There was a problem that.

The object of the present invention is to solve the above-mentioned problems of the prior art,
Another object of the present invention is to provide a signal processing circuit in which signal deterioration does not occur even if a signal from the VDP or VDP is input, without motion detection or malfunction of the YC separation circuit.

[Means for solving problems]

The purpose is to detect the non-inversion state of the color burst phase, paying attention to the fact that the phase of the color burst signal in the horizontal blanking period is not inverted between frames in the VTR or VDP reproduction signal. And means for switching between adaptive signal processing in space-time and signal processing only in space,
This is achieved by stopping the adaptive signal processing and switching to signal processing only in space when it is detected that the phase of the color burst is not inverted between frames.

[Operation] For a signal such as VTR or VDP in which the phase of the color burst signal in the horizontal blanking period is not inverted between frames, the detection circuit detects the phase non-inversion state of the color burst signal. As a result, the detection circuit switches the signal processing circuit from the adaptive signal processing in space-time to the signal processing only in space, so there is no problem of malfunction in motion detection, and in the region where the signal correlation is strong in this case. The signal processing is performed and the deterioration of the signal is eliminated.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The video signal is shown by a solid line and the control signal is shown by a broken line. In FIG. 1, 101 is a color television signal, 102 is an A / D converter, 1
03 is a motion adaptive YC separation circuit, 104 is an RGB conversion circuit, 105 is a motion adaptive scanning line interpolation circuit, 106 is a color burst non-inversion detection circuit within the horizontal blanking period, 107 is a spatial YC separation circuit, 108 Is an RGB conversion circuit, 109 is a scanning line interpolation circuit in space, 110 is a switching circuit, 111 is a time compression and multiplexing circuit,
112 is a D / A converter, 113 is a cathode ray tube, and 114 is a motion detection circuit. Here, the case of the NTSC system as a color television signal will be described as an example. In the NTSC system, the color subcarrier frequency, horizontal frequency and frame frequency are f
_{If SC} , f _H , f _r , then there are the following two relationships.

If we find the relationship between f _SC and f _r from these two equations, Becomes Therefore, the phase of the color subcarrier has a relationship of returning to the original in two frames, and the phases of the color bursts in the horizontal blanking period between frames are mutually inverted.

Naturally, the signal sent from the broadcasting station satisfies the expression (3), but the reproduction signal at the time of the special reproduction of the current VTR or VDP does not satisfy the relationship of the expression (3).

Therefore, in the present invention, it is examined whether or not the relation of the expression (3) is satisfied, and when this condition is not satisfied, YC separation and scanning line interpolation in the space where the correlation is strongest in this case are used. The above is the basic idea of the present invention.

Next, a specific operation of the present invention will be described with reference to FIG. First, when a signal conforming to the NTSC signal standard is input, the color burst non-inversion detection circuit 106 detects that the phase of the color burst signal is inverted between frames, and the switching circuit 110 moves to adapt. Scanning line interpolation circuit 105
Operates to pass the output. Then, in operation,
The configuration is the same as that of FIG. 2, and adaptive type signal processing in space-time is performed, and it is possible to output a surface in which the deterioration problem of the current broadcasting system is improved.

On the other hand, in the case of inputting a signal that does not fit within the standard of NTSC signal, such as a reproduction signal at the time of special reproduction of VTR or VDP, the color burst non-inversion detection circuit 106
It is detected that the phase of the color burst signal is not inverted between frames, and the switching circuit 110 is set to the scanning line interpolation circuit 1 in the space.
09 Switch to pass the output. Then, the in-space YC separation circuit 107, the RGB conversion circuit 108, the in-space scan line 109
Since the video signal subjected to the signal processing in (1) is sent to the time compression / multiplexing circuit 111 via the switching circuit 110, it can be processed in the spatial region having the strongest correlation. Therefore, there is no problem in motion detection malfunction or inability to perform signal processing between frames.

Further, in the configuration of FIG. 1, the color burst non-inversion detection circuit
The processing only in the space and the adaptive signal processing in the space-time are switched by the 106, but in addition, when the color burst non-inversion detection circuit 106 detects the color burst non-inversion, the motion detection circuit Control 114,
It is also possible to forcibly set the moving image mode and perform processing only in the space. By doing so, it is not necessary to newly provide each signal processing circuit of the in-space YC separation circuit 107, the RGB conversion circuit 108, and the in-space scanning line interpolation circuit 109, so that the circuit becomes simple.

Yet another embodiment is shown in FIG. The configuration of FIG. 5 is the first
Portions that are the same as those in the figure and have the same functions are assigned the same numbers as in FIG. The difference between FIG. 5 and FIG. 1 is that the 501 comb filter and
It is the A / D conversion circuit of 02,503. That is, in Fig. 1, Y in space
Although the C separation circuit 107 is composed of a digital circuit, it may be composed of an analog circuit as shown in FIG.

The operation of FIG. 5 when the color burst non-inversion detection circuit 106 detects that the phase of the color burst signal is inverted between the frames of the input signal 101 is the same as that of FIG. Then, the color burst non-inversion detection circuit 106
However, when it is detected that the phase of the color burst signal is not inverted between frames of the input signal 101, the color burst non-inversion detection circuit 106 causes the switching circuit 110 to select the output of the spatial scanning line interpolation circuit 109. To switch. After switching in this way, the color television signal 101 which is the input signal is once YC separated by the analog comb filter 501 which is one of the YC separation circuits in the space, and the A / D converters 502 and 503.
Convert to digital value with. After that, the RGB conversion circuit 108 converts the Y, C signals into RGB signals, and the scanning line interpolation circuit in the space.
If scanning line interpolation is performed at 109 and a signal is sent to the time compression / multiplexing circuit 111 via the switching circuit 110, the image processed in the same space as in FIG. 1 can be viewed on the cathode ray tube 113. is there.

The case where an analog line comb filter is used as the in-space YC separation circuit 107 has been described above with reference to FIG. 5, but as another embodiment of the present invention, a band pass filter, a low pass filter, and a digital filter are used. Examples include a line comb filter, and an intra-space adaptive YC separation filter in which these filters are adapted in space, as the intra-space YC separation circuit 107 in FIG. Further, as can be seen from the above description, the spatial YC separation circuit 107 may be either digital or analog.

Next, the color burst non-reversal detection circuit 106 will be explained promptly.

FIG. 6A shows an example of the color burst non-inversion detection circuit 106. 601 is a color television signal, 602 is a one-frame delay circuit, 603 is an addition circuit, 604 is an absolute value conversion circuit, and 60.
Reference numeral 5 is an integrating circuit, 606 is a comparing circuit, and 607 is an output signal.

FIG. 6 (b) is a waveform diagram for explaining the operation of FIG. 6 (a), (i) is the case where the phase of the color burst is correctly inverted between frames, and (ii) is the color. This is the case where the burst phase is not inverted between frames.

When the color burst signal is inverted between frames as shown in (i), the addition is performed by the addition circuit 603 between frames to be almost 0, and even if it is passed through the absolute value conversion circuit 604 and the integration circuit 605, it is 0. It remains. Therefore, even if the value 0 is compared with a predetermined value by the comparison circuit 606, the output 607 is 0.
It means that the phase between the frames of the color burst is inverted. On the other hand, when the phase of the color burst signal is not inverted between frames, for example, when the phases are in phase between frames, the absolute value conversion circuit 604 output becomes as shown in (ii). Therefore, this is the integration circuit
Through 605, if the comparison circuit 606 compares with a predetermined value, 1 is output. This indicates that the color burst phase is not inverted between frames.

Further, when the phase of the color burst is not inverted between frames and the phase is shifted at an arbitrary phase, it is possible to detect by the same operation.

FIG. 7 (a) shows another example of the color burst non-inversion detection circuit. In FIG. 7A, 701 is a color burst signal, 702 is a phase comparison circuit, 703 is a VCO, 704 and 705 are low-pass filters, 706 is a comparison circuit, 707 is a sample hold circuit, and 707 is an output signal. A waveform diagram for explaining the operation of FIG. 7 (a) is shown in FIG. 7 (b). In FIG. 7, (i) is the case where the phase of the color burst signal is inverted between frames, and (ii) is the case where the phase of the color burst signal is not inverted between frames.

In FIG. 7A, the phase comparison circuit 702, the VCO 703, and the low pass filter 704 form a PLL circuit, and are locked to the phase of the input color burst signal 701. As shown in (i) of FIG. 7B, when the VCO output 703 is locked to the color burst signal 701, the phase difference between the color burst signal 701 and the VCO output 703 is maintained at 90 °. . The output of the phase comparison circuit 702 at this time is as shown in (c), and therefore the output of the low-pass filter 705 is (D).
become that way. And 0 for sample hold 707 output
Is output. On the other hand, when the phase of the color burst becomes discontinuous between frames as in the special reproduction of VDP, the output of the phase comparison circuit 702 becomes as shown in (ii) of (b), which is passed through the low pass filter 705. When the sample and hold is performed, the H level signal of (E) is obtained.

By the way, an example of detecting only the state that the phase of the color burst is not inverted between frames and switching between adaptive signal processing in space-time and signal processing only in space has been described above. It is not always necessary to use only this condition as a switching signal for switching between the adaptive signal processing in space-time and the signal processing only in space.
That is, other non-NTSC signal state detection signals may be mixed and used for state detection that the phase of this color burst is not inverted between frames. For example, the block diagram of FIG. 8A is this example. FIG. 8A shows a frequency dividing circuit 8 for the clock signal 801 locked to the burst and the clock signal 802 locked to the horizontal synchronizing signal.
After dividing by N by 03,804, it is judged by the frequency comparison circuit 805 whether the frequencies are equal, and the judgment output and the color burst non-inversion detection output are mixed, and the adaptation in the space-time described so far is performed. It may be a switching control signal of a switching circuit for switching between the signal processing circuit of the shape and the signal processing circuit only in the space. As this mixing method, for example, the logical sum of the signals of each other may be taken.

Then, a supplementary explanation will be given on the scanning line interpolation circuit in the space. 9A and 9B show scanning line interpolation circuits in space, FIG. 9A shows an example of repeatedly using a previous scanning line as an interpolation scanning line, and FIG. This is an example of using the average of scanning lines.

First, FIG. 9 (a) will be described. In (a), the scanning line interpolation circuit is composed of an input scanning line 811 and a 1 / 2H delay circuit 812, then passed through time compression circuits 813 and 814, multiplexed by a multiplexing circuit 815, and scanning line interpolation was performed. Output the output signal 816.

Next, this operation will be described with reference to the waveform chart of FIG. First, when the input scanning line 811 is sent as shown in FIG. 9 (c), the 1 / 2H delay circuit delays this signal for a 1 / 2H period and outputs it. Here, the time compression circuit is a circuit that outputs a signal obtained by compressing the time of an input signal by half. Therefore, the output waveforms of the time compression circuits 813 and 814 are time-compressed waveforms of the input signal.

Then, the multiplexing circuit 815 switches these time-compressed signals every 1 / 2H period. Then, a signal which is time-compressed with respect to the input scan line 811 and which is interpolated so as to repeat the previous scan line is obtained.

On the other hand, the scanning line interpolation circuit in FIG.
1, 1 / 2H delay circuits 817 and 818, an adder circuit 819, and a 1/2 coefficient circuit 820. The time compression circuit 8 is similar to FIG. 9 (a).
It is then connected to the multiplexing circuit 815 via 13,814.

This operation is similar to FIG. 9 (a) and will be described with reference to FIG. 9 (c). The input scanning line 811 which is the current signal is delayed by the 1 / 2H delay circuit 817 for the 1 / 2H period and sent to the period compression circuit 813. The interpolated scan line signal is created by averaging the input scan line 811 delayed by 1H by the 1 / 2H delay lines 817 and 818 and the input scan line 811 by the adder 819 and the 1/2 coefficient circuit 820. Thereafter, this signal is sent to the time compression circuit 814 and time-compressed. Then, if the outputs of the time compression circuits 813 and 814 are switched by the multiplexing circuit 815, the average of the preceding and following scanning lines is used as the interpolation scanning line. It is possible to obtain a signal.

By the way, in the embodiments of FIGS. 1 and 5, the case has been described in which scanning line interpolation is performed to operate at a horizontal frequency twice as high as that of a normal NTSC receiver. However, this scanning line interpolation is not performed and normal scanning is performed. Obviously, the present invention is effective when operating at the same horizontal frequency as the NTSC receiver.

By the way, up to now, the case where the phase difference between the frames of the color burst is used as the detection of the VTR or VDP has been described. In addition to this, as a method of detecting VTR or VDP, a method of looking at the phase difference of horizontal synchronization between frames may be used to switch between adaptive signal processing in space-time and signal processing only in space. An example of this is shown in FIG. In FIG. 10, 901 is a color television signal, 902 is a one-frame delay circuit, and 9
03 is a subtraction circuit, 904 is an absolute value conversion circuit, 905 is an integration circuit, 90
6 is a comparison circuit and 907 is a holding circuit. If the 1-frame delay circuit 902 is moved by the signal locked to the color burst signal, the burst signal frequency will be changed in VTR and VDP.
Since there is no frequency relationship with the horizontal sync or vertical sync frequency, the phase of the horizontal sync signal is different from the phase of 901 as in the output 902 in FIG. 10 (b). Therefore, after this, the subtraction circuit 9
The value is subtracted in 03, the absolute value is obtained by the absolute value conversion circuit 904, integrated by the integration circuit 905, and compared with a predetermined value by the comparison circuit 906. And if this value is held in the holding circuit 907, it will be "H" in VTR.
Output level signal. This detection signal may be used.

〔The invention's effect〕

According to the present invention, even if a signal such as VTR, VDP special reproduction that does not satisfy the NTSC signal specifications is input, it is automatically detected,
In this case, the signal processing can be performed only in the space having the highest correlation, so that it is possible to always perform the processing without signal deterioration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram for explaining a conventional technique, and FIG. 3 is a motion adaptive type YC.
An example of a separation circuit, FIG. 4 is a block diagram showing an example of a motion adaptive scanning line interpolation circuit, FIG. 5 is a block diagram showing another embodiment of the present invention, and FIG. 6 is a color burst non-inversion detection circuit. FIG. 7 is a block diagram and waveform diagram showing an example, FIG. 7 is a block diagram and waveform diagram showing an example of another color burst non-inversion detection circuit, and FIG. 8 is a supplementary explanation for the configuration of the color burst non-inversion detection circuit. FIG. 9, FIG. 9 is a block diagram and a waveform diagram for explaining the spatial scanning line interpolation circuit, and FIG. 10 is an explanatory diagram of a circuit for detecting a phase shift of horizontal synchronization. 101 …… Color television signal 103 …… Motion adaptive YC separation 105 …… Motion adaptive scan line interpolation 106 …… Color burst non-inversion detection 107 …… Spatial YC separation 109 …… Spatial scan line interpolation 110 …… SW 111 …… Time compression and multiplexing 113 …… CRT

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ikuya Arai, Ikuya Arai, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Electric Appliances Research Laboratory, Hitachi, Ltd. (72) Ichio Nakagawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa House number Incorporated company Hitachi, Ltd. Home Appliances Research Laboratory (72) Inventor Masahiko Achiha 1-280 Higashi Koigakubo, Kokubunji, Tokyo Metropolitan Research Institute Ltd. (72) Kazuo Ishikura 1-280 Higashi Koigakubo, Kokubunji, Tokyo Stock Central Research Laboratory, Hitachi, Ltd. (56) References JP-A-61-296886 (JP, A)

Claims (4)

[Claims] 1. An input color television signal is a standard signal satisfying a broadcasting standard by detecting whether or not a phase of a color burst signal of the input color television signal has an inversion relation between frames. , Or a non-standard signal detecting means for detecting whether or not the signal is a non-standard signal deviating from the broadcasting standard, and at least a luminance / color signal separating means, and the input color television according to the detection result of the non-standard signal detecting means. When the signal is a standard signal, when the input color television signal is a non-standard signal by subjecting the input color television signal to processing that is adapted to the amount of motion of an image and separating and outputting a luminance signal and a color signal A signal processing means for processing the input color television signal only in a space for each screen to separately output a luminance signal and a color signal. Signal processing circuit that. 2. The non-standard signal detection means according to claim 1, wherein the non-standard signal detection means delays the color burst signal of the input color television signal for one frame period, and the input / output color burst of the delay means. A signal processing circuit comprising: an addition means for adding signals and a determination means for determining the level of the addition means. 3. The input color television signal is a standard signal satisfying a broadcasting standard by detecting whether or not the phase of a horizontal synchronizing signal of the input color television signal is matched between frames, Alternatively, the input color television signal has a non-standard signal detecting means for detecting whether it is a non-standard signal deviating from the broadcasting standard, and at least a luminance / color signal separating means, and a detection result of the non-standard signal detecting means. Is a standard signal, the input color television signal is subjected to processing adapted to the amount of motion of an image to separately output a luminance signal and a color signal, and when the input color television signal is a non-standard signal, A signal processing means for processing the input color television signal only in a space for each screen to separate and output a luminance signal and a color signal. Physical circuit. 4. The nonstandard signal detecting means according to claim 3, wherein the non-standard signal detecting means delays the horizontal synchronizing signal of the input color television signal by one frame period, and the input / output horizontal synchronizing of the delaying means. A signal processing circuit comprising: subtraction means for subtracting a signal; and determination means for determining the level of the subtraction means.