JPS62175091A - Color television signal processing circuit - Google Patents

Abstract

PURPOSE:To enlarge an applicable range of a signal processing circuit having a picture memory by changing over a YC separating circuit and a scanning line interpolation circuit into a circuit in a field on a non-standard signal under the control of an identifying means and sampling a horizontal synchronizing signal from a double speed video signal. CONSTITUTION:The delay of a signal is generated for a processing in the YC separating circuit 5 or the scanning line interpolation circuit 7 and when a cycle signal (especially, the horizontal synchronizing signal) defecting and driving a display monitor 14 is sampled from an input color television signal and supplied to the monitor 14, a time slippage is produced between the synchronizing signal and a video signal. Therefore, the synchronizing signal included is digitized in an A/D converter 2, the horizontal synchronizing signal HD is separated in a synchronizing separator circuit 13 from an output signal of a D/A converter 10 in which the speed is made twice as fast as before, by which the display monitor 14 is driven. Thereby, the video signal and the horizontal synchronizing signal supplied to the display monitor have no time slippage but have the same time fluctuation component, so that this fluctuation is cancelled on a screen and a correct reproducing picture is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a television signal processing circuit, and particularly to a television signal suitable for processing not only standard color television signals but also television signals that deviate from the standard color television signals. Related to signal processing circuits.

[Conventional technology]

Signal processing methods are known in which a color television signal is separated into a luminance signal and a color difference signal using a frame memory, and an interlaced scanning television signal is converted into a progressive scanning signal by interpolating scanning lines using a field memory. (Japanese Unexamined Patent Publication No. 129892/1982, Japanese Unexamined Patent Publication No. 58/1983
77373).

In signal processing circuits that use image memories, such as field memories and frame memories, that have a delay approximately equal to the vertical scanning period of the television signal or an integral multiple thereof, the input television signal must conform to the standard color television system. If the output signal is a signal, a high quality output signal is obtained. However, no consideration has been given to signals that deviate from the standard color television system, such as output signals from widely used home VTRs.

[Problem that the invention seeks to solve]

In the case of non-standard signals such as those from home VTRs, the time axis fluctuates significantly and the phase of the color subcarrier signal does not have an offset relationship with the horizontal scanning period, so it is necessary to use delays in the field period or frame period. The problem with the conventional technology is that correct processing cannot be performed and the image quality deteriorates considerably.

An object of the present invention is to provide an image memory that can correctly handle television signals that do not conform to the standard color television system, that is, the horizontal synchronization signal during the blanking period and the phase of the color subcarrier do not match with the standard television signal. The objective is to provide a signal processing circuit that can

[Means for solving problems]

The above purpose is to phase-lock the clock signal that operates the signal processing circuit to the signal in the blanking period of the input color television signal, and to synchronize the signal processing circuit with in-field processing circuits such as the YC separation circuit and the scanning interpolation circuit. This is achieved by

Note that a horizontal synchronization signal or a color burst signal is used as a signal in the blanking period.

In addition, when using a horizontal synchronizing signal, YC separation is performed within the field or within the line.

If it is a color burst signal, a horizontal synchronization signal that polarizes the color display is extracted from the doubled speed video signal.

[Effect]

When the clock signal that operates the signal processing circuit is phase cycled to the color burst signal of the input color television signal, the pixel position will no longer be locked to the horizontal synchronization signal in the case of a non-standard signal. Clock frequency to color subcarrier frequency f
If it is 4 times sc, the delay of 910 clocks is exactly L
This will not result in a delay of H, but will include some time fluctuations. Since this variation is slight, signals separated by 910 clocks maintain a strong correlation, and this can be effectively utilized to perform YC separation between lines and scanning line interpolation. In time compression processing for progressive scan conversion, which converts an incrementally scanned signal into a progressively scanned signal, 455 clock cycles do not represent the correct II(I) of the doubled-speed signal, and some time fluctuations occur. If the horizontal synchronization signal that deflects the display is extracted from the doubled-speed video signal, the displayed video signal and the horizontal deflection will have the same time-varying component, and the screen will contain this time-varying component. does not appear and the correct image is displayed.

Furthermore, by synchronizing the phase of the clock signal that operates the signal processing circuit with the horizontal synchronization signal of the input television signal, which varies in the time axis, the arrangement of pixels is aligned with respect to the horizontal synchronization signal. Therefore, by performing pixel-by-pixel calculations using the horizontal synchronization signal as a reference, the problem of malfunctions due to time axis fluctuations of non-standard television signals does not occur.

The problem that there is no offset relationship between the color subcarrier phase of a non-standard television signal and a horizontal synchronization signal can be solved by not using line period (field period or frame period) delay for YC separation. That is, an identification means is provided for identifying that the input signal is a non-standard television signal.

A switching means operated by this identification means is provided in the YC separation, so that in the case of a non-standard signal there is an in-line YC separation circuit. This makes it possible to avoid malfunctions due to no offset relationship.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the same figure, an NTS (: system) composite color television signal input to an input terminal 1 is digitized by an A/D converter 2. An input NTSC signal is also input to a clock generation circuit 3, and the input NTSC signal is digitized by an A/D converter 2. A clock signal phase-locked to the color burst signal is output and supplied to the A/D converter 2 and others.

The output of the A/D converter 2 is input to a motion adaptive YC separation circuit 5 using a frame memory and a line memory, and a motion detection circuit 6. The YC-separated luminance signal Y is input to a motion-adaptive scanning line interpolation circuit 7 using a field memory and a line memory, and is converted into a double-speed sequential scanning signal. The YC-separated carrier color signal C is demodulated into a color difference signal by a demodulation circuit 8, and converted into a double-speed sequential scanning signal by a scanning line interpolation circuit 9 using a line memory. The obtained sequential scanning signal is returned to an analog signal by the D/A converter 10.11, and the matrix circuit 12 converts the three primary color signals (red R1
green G, blue B) and output to the output terminal.

In FIG. 1, a YC separation circuit 5 that is particularly relevant to the present invention
．． A specific configuration diagram of the scanning line interpolation circuit 7 and the motion detection circuit 6 is shown in FIG. Period (a) is an example of a motion adaptive VC separation circuit 5 and a scanning line interpolation circuit 7. In the figure, if the input color television signal is Xo, the signal delayed by LH (H is the horizontal scanning period) in line memory 5 is defined as X-t, and the signal delayed by 525H in frame memory 16 is defined as X-5zs, then The resolving power Cz of the carrier color signal between frames for processing an image portion can be extracted as Xo-X-5zb C = □ Happ (1). Here, IBPF indicates the transfer characteristic of a bandpass filter that extracts a signal in the carrier color signal band. On the other hand, the separated output C2 of the carrier color signal of the intra-field processing for processing the moving image part is XOX-1 C2= = Hnpr .
- Can be extracted as (2). Therefore, the desired carrier color signal C obtained by mixing C1 and Cz using the motion coefficient k (0≦≦1) can be obtained by using equations (1) and (2).
) is required. The YC separation circuit 5 shown in FIG.
A luminance signal Y is obtained by subtracting from the SC signal. That is, the subtraction circuit 1 calculates the difference between the signals X-1 and X-521I.
7, and its output is multiplied by a motion coefficient k in a coefficient circuit 18. When the result is added to X-1 in the adder circuit 19, the formula (3
) can be calculated.

Therefore, the subtraction circuit 20 subtracts from Xo, and the coefficient circuit 21
By multiplying by 1/2 and extracting the components of the carrier color signal band using the bandpass filter 22, the desired carrier color signal C can be obtained by calculating equation (3). When the subtraction circuit 23 subtracts the C signal from the input signal Xo, a desired luminance signal Y is obtained.

Next, the motion adaptive scanning line interpolation circuit 7 will be described. Y
The C-separated luminance signal Y is input to a line memory 24 and a field memory 25, and a signal Y' of an interpolated scanning line directly above the Y signal on the screen is determined. The interpolated signal Y-2fl11 of the still image portion is generated from the previous field signal Y-2fl11 delayed by 2 63 H and located at the same position as Y'. That is, Yz' = Y-zaa - (
4) On the other hand, the interpolation signal Y2' of the moving image section is the same as the current signal Y and 1H.
It is created using the average value of the delayed signal Y-4.

Y+Y-1 Y2'=□...(5) Yz'
By mixing Yz' and Yz' into a motion coefficient, a desired interpolation signal Y' can be obtained as shown in the following equation.

Y' = kY1' + (1-k) Yz'... (6
) Adder circuit 26.1/2 coefficient circuit 27 in FIG. 2(a). Subtraction circuit 28. Coefficient circuit 29 which also multiplies the motion coefficient k. Adder circuit 30 is a circuit that performs the calculation of equation (6) to obtain interpolated signal Y'. The signal Y of the current scanning line and the signal Y' of the interpolation scanning line are processed by time compression circuits 31 and 32 to reduce the time axis by 1/2.
compressed into.

When the switching circuit 33 is switched in units of time-compressed scanning lines, the horizontal scanning period is halved, and a progressive scanning signal is obtained in which all scanning lines are scanned during the field period of the input color television signal.

When the input color television signal is a signal from a home VTR or the like, there is a fluctuation in the time axis, so a signal before a frame period or a field period cannot be used. This can be realized by setting the value of the motion coefficient to 0" (moving image mode). FIG. 2(b) shows the configuration of an embodiment of the motion detection circuit.

That is, using the input color television signal XO and the signal X-, which is delayed by the frame memory 34, the subtraction circuit 35. Reduced pass filter 36. When the absolute value signal of the low frequency component of the frame 11 difference is determined by the absolute value circuit 37, the motion information signal My of the low frequency component of the luminance signal is obtained. On the other hand, band pass filters 38 and 39, absolute value circuit 40
．． 41 and a subtraction circuit 42, a frame difference signal of the absolute value of the carrier color signal band component is obtained. This is the absolute circuit 43
When demodulated by the reduced pass filter 44, a motion information signal Mc of the color difference signal is obtained. These two signals are added by an adding circuit 45, and converted into a motion coefficient k by a converting circuit. When the input signal is a non-standard signal from a home VTR or the like, the switching circuit 47 forcibly sets the motion coefficient to '0'' under the control of its identification signal S (described later). Both interpolation circuits 7 are set to intra-field processing mode.

In FIG. 1, the input color television signal is also input to an identification circuit 4 for identifying non-standard signals, and when a non-standard signal is input, the switching circuit 47 of the motion detection circuit described above is switched under the control of the identification signal S.

Non-standard signals can be identified by (1) forcing the mode into non-standard signal mode by manual operation, or (2) providing a dedicated input terminal for non-standard signals and inputting the input signal there. (3) How to use non-standard signal mode if
The synchronization signal part of the input color television signal is monitored, and if the phase changes between frames (specifically, for example, the number of clocks in the frame period is counted and it differs from the predetermined number of clocks), it is set to non-standard signal mode. Alternatively, the sum signal between the lines in the color burst portion is monitored, and if the signal of the color subcarrier component occurs above a certain level, the offset relationship has disappeared, so the presence or absence of this signal is determined and the identification signal is determined. A method such as that can be adopted. The identification circuit 4 in FIG. 1 is a block diagram corresponding to this (3).

In the figure, signal delays occur in the YC separation circuit 5 and the scanning line interpolation circuit 7 due to processing, and the display monitor 1
When a periodic signal (particularly a horizontal synchronization signal) for driving the deflection of the video signal 4 is extracted from the input color television signal and supplied to the monitor 14, a time lag occurs between the video signal and the synchronization signal. When a standard signal with no temporal variation is input, this shift does not affect the reproduced image. On the other hand, in the case of a non-standard signal, this shift results in horizontal fluctuation of one screen with temporal fluctuations. In order to avoid this, in the embodiment of FIG.
The horizontal synchronization signal IIr) is separated from the output signal of the D/A converter 10 after doubling the speed by the /D converter 2, including the synchronization signal, and the horizontal synchronization signal IIr) is used to drive the display monitor 14. let As a result, since the video signal and the horizontal synchronization signal supplied to the display monitor have the same time-varying component without any time lag, this fluctuation is canceled on the screen, and a correct reproduced image can be obtained.

Note that the vertical deflection synchronization signal has a long period, and the temporal fluctuations of the non-standard signal can be ignored, and even the synchronization signal extracted from the input signal does not produce an original part in the reproduced image.

FIG. 3 is a diagram showing the configuration of an embodiment of the YC separation circuit section in another embodiment of the television (FF processing circuit) of the present invention, in which parts corresponding to the first embodiment are given the same numbers. .

In particular, in this embodiment, as the clock signal of the signal processing circuit,
This is effective when using a clock signal phase-locked to the horizontal synchronization signal of the input television signal. That is, the clock signal generation circuit 3 of FIG. 1 generates a clock signal whose phase is locked to the horizontal synchronization signal of the input television signal.

When the identification circuit 4 determines that the input television signal is a standard television signal, the switches 48 and 49 select the outputs Y and C of the YC separation circuit 5. The configuration of the YC separation circuit is the same as that shown in block 5 of FIG.

Further, when the identification circuit 4 determines that the input television signal is a non-standard television signal, the switches 48 and 49 select the outputs Y' and C' of the YC separation circuit 5'. When the input television signal is a non-standard signal, the input television signal is converted into a luminance signal Y' by the reduced pass filter 50.
is extracted, and a carrier color signal C' is extracted by a bandpass filter 51. In the case of a non-standard signal such as a home VTR, there is no offset relationship in which the phase of the color subcarrier signal is inverted between lines, so YC separation is performed by simple intra-line processing using a reduction pass filter or a band pass filter.

FIG. 4 is a circuit diagram of another embodiment of the motion detection circuit 6, in which the configuration on the output side is changed from blocks 37 and 34 in FIG. figure(
It is omitted because it is the same as b). Motion information My of the low frequency component of the luminance signal is obtained from the absolute value circuit 37, and motion information Mc of the color difference signal is obtained from the reduced pass filter 44. If it is an input television signal, the switch 52 is connected to the upper side by the output signal of the discrimination circuit 4, and the adder 45 obtains the sum of the signals My=Mc, which is converted into a motion coefficient by the conversion circuit 46. When the input television signal is a non-standard signal, the motion information Me cannot be used because there is no condition that the carrier color signal has inverted polarity between frames. Therefore, the switch 52 is connected to the lower side by the identification signal S of the non-191 quasi-signal, and the signal Me input to the adder circuit 45 is forced to 1101.
Set the value to 7 (no movement).

As mentioned above, when the tarok signal is phase clocked to the horizontal scanning period of the input television signal, YC separation is performed as intra-line processing, the motion coefficient is extracted using the frame difference signal of the low frequency component of luminance, and scanning line interpolation is performed as standard. As in the case of television signals, field memory is used.

〔Effect of the invention〕

According to the present invention, even if a signal that does not conform to the standard method is input to a signal processing circuit having an image memory such as a field memory or a frame memory, the signal processing can be performed without causing a problem with the image memory. This has the effect of greatly expanding the scope of application of signal processing circuits with

[Brief Description of the Drawings] Fig. 1 shows a color television signal processor according to the present invention]! l
! A configuration diagram of one embodiment of the circuit, FIG. 2 is a circuit diagram of the YC separation circuit, scanning line interpolation circuit, and motion detection circuit used in the above embodiment, and FIG. 3 is another embodiment of the YC separation circuit section. FIG. 4 is a block diagram of a modified portion of the motion detection circuit in FIG. 2. 2... A/D converter, 3... Clock generation circuit, 4
...Identification circuit, 5...YC separation circuit, 6...Motion detection circuit. 7.9...Scanning line interpolation circuit, 8...Demodulation circuit, 10
゜11...l)/A converter, 12...matrix,
1.3... Synchronization separation circuit, 14... Display monitor, 15°24... Line memory, 1.6.34.
...Field memory, 17, 19, 20, 23, 26
,28,30°35.42.45... Addition (subtraction) circuit, 1.8, 2],'. 27.29... Coefficient circuit, 22, 36, 38. :39
゜44...Filter, 25...Field memory,
31°32...Time compression memory, 33.47...Switching circuit, 37.40,41. ．． 43... Absolute value circuit,
46...Hendoryo 3 Figure 4

Claims (1)

[Scope of Claims] 1. A delay memory that operates with a clock signal phase-locked to a color burst signal of an input color television signal and has at least a field period or more, and a YC using the same.
In a color television signal processing circuit having a separation circuit and a scanning line interpolation circuit, an identification means for identifying that an input signal is a non-standard signal of a home VTR or the like, and a control of the identification means to detect a non-standard signal. A switching means is provided in which both the YC separation circuit and the scanning line interpolation circuit become in-field processing circuits, and furthermore, the horizontal synchronization signal for deflecting the display at least in the case of a non-standard signal is a video signal whose speed is doubled. A color television signal processing circuit characterized in that it is extracted from. 2. A television that operates with a clock signal phase-locked to the horizontal synchronization signal of an input television signal and has a delay memory of at least a field period or longer, a YC separation circuit, a scanning line interpolation circuit, a motion detection circuit, etc. using the delay memory. The signal processing circuit includes an identification means for identifying that an input signal is a non-standard signal of a home VTR or the like, and a switching means for controlling the identification means to cause the YC separation circuit to become a YC separation circuit for in-line processing. A television signal processing circuit characterized in that: 3. The television signal processing according to claim 1, further comprising a second switching means that causes the scanning line interpolation circuit to become a scanning line interpolation circuit for intra-field processing under the control of the identification means. circuit. 4. In claim 1 or 2, under the control of the identification means, the motion detection circuit becomes a motion detection circuit that extracts motion information of only low frequency components from which a carrier color signal frequency band is removed. A television signal processing circuit comprising a third switching circuit.