JPS6251392A - Television signal processing circuit - Google Patents

Abstract

PURPOSE:To expand the application range of a signal processing circuit by arranging the 1st signal processing circuit having a picture memory and the 2nd signal processing circuit not having a picture memory in parallel and providing a changeover means for selecting the 2nd signal processing circuit in processing a signal not in compliance with the standard color television system. CONSTITUTION:A television signal to be processed is inputted to the 1st and 2nd signal processing circuits and inputted to a decision circuit 7 deciding whether or not the signal is the standard color television signal. The decision circuit 7 decides whether or not the signal is in compliance with the standard television system based on whether or not a chrominance subcarrier signal and a scanning frequency are in a prescribed offset or whether or not a field period and a frame period have timewise fluctuation. When the decision circuit 7 decides that the signal is not in compliance with the standard color television system, its output signal controls a changeover circuit 4 and an output of the 2nd signal processing circuit is obtained at a terminal 6.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] 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.

[Background of the invention]

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. It is being (4? Publication No. 129892/1989, Japanese Patent Application Publication No. 58/1973)
8-77373)) In a signal processing circuit using an image memory such as a field memory or a frame memory that has a delay approximately equal to the vertical scanning period of the television program signal or an integral multiple thereof, the input television program signal is standard. If the signal conforms to the color television system, a high quality output signal can be obtained. However, when processing the output signals of widely used home VTRs, etc., these signals may have significant fluctuations in the time axis, or the subcarrier frequency of one color and the scanning frequency may not have a predetermined relationship. The signal deviates from the standard color television signal. Therefore, the above-mentioned signal processing using delays in the field period or frame period cannot perform correct processing. For example, when separating luminance and color using a frame memory, the phase of the color subcarrier should originally be inverted (180 degrees different) from the signal one frame period before, but in a home VTR, Since this is not the case for signals such as , it is not possible to correctly separate the luminance signal and chrominance signal from interframe calculations. Furthermore, in scanning line interpolation using a field memory, the field period is not constant and a correct interpolation signal cannot be obtained. As a result, when a processing circuit with an image memory such as a field memory or a frame memory processes a signal from a home VTR, the resulting signal is a very degraded signal. OBJECTS OF THE INVENTION It is an object of the present invention to provide a signal processing circuit having an image memory that can correctly handle television signals that do not conform to the standard color television system.

[Summary of the invention]

In order to achieve the above object, the present invention juxtaposes a first signal processing circuit having an image memory such as a field memory or a frame memory and a second signal processing circuit having no image memory, and The present invention is characterized in that it has a switching means for selecting the second signal processing circuit when processing a signal that does not conform to the John system.

FIG. 1 shows a basic configuration diagram of the present invention. In the figure, a televised signal to be processed that is input to terminal l is input to a first signal processing circuit having an image memory and a second signal processing circuit having no image memory. The output of each signal processing circuit is switched and selected by a switching circuit 4, and if a signal not conforming to the standard color television signal is to be processed, the switching circuit 4 is controlled by a control signal applied to a terminal 5. The output of the second signal processing circuit 3 is selected and output to the terminal 6.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the invention. In the same figure, the first
1. The second signal processing circuits 2, 3 and switching circuit 4 are the same as in FIG. In this embodiment, the televised signals to be processed are first . The signal input to the second signal processing circuit is C.
ζ is input to a determination circuit 7 which determines whether this signal is a standard color television signal or not. The determination circuit 7 determines whether the standard color television system is selected depending on whether there is a predetermined offset relationship between the one-color subcarrier liquefaction signal and the scanning frequency, or whether there are temporal fluctuations in the feed cycle or frame cycle. Determine whether the rules are met. If the determination circuit 7 determines that the standard color television system is not followed, the switching circuit 4 is controlled by the output signal,
The output of the second signal processing circuit is obtained at terminal 6.

FIG. 3 shows another embodiment of the invention. In the same figure, 2
, 3 are the same first and second signal processing circuits as in FIGS. 1 and 2. In this embodiment, the first. Second signal processing circuit 2.
The output of 3 is input to the coefficient circuit 8.9, and is multiplied and (
1-k), are added together in an adder circuit 11, and are output to a terminal 6. Here, k is 0 to 1 depending on the presence or absence of movement.
indicates a motion coefficient that varies between . The motion coefficient is extracted by the motion detection circuit 10 as motion information included in the television signal. Is it movement? In the still image part, k approaches l, and the ratio of the output signal of the first signal processing circuit using the image memory increases, and in the part of the image that moves rapidly and has large changes, k approaches 0. As a result, the proportion of the output signal of the second signal processing circuit increases. If the television signal to be processed does not conform to the standard color television signal, the control signal appearing at terminal 12 controls the motion detection circuit to force the motion coefficient k to 0 and The output of the signal processing circuit 3 of No. 2 is made available to the terminal 6. The signal appearing at the terminal 12 may be a manually commanded signal, a signal that changes the input television signal from a specific terminal, or an output signal from the determination circuit 7 shown in FIG. 2. This also applies to the signal applied to the terminal 5 for the first time.

FIG. 4 shows a detailed block configuration when the present invention is applied to a motion adaptive YC separation circuit that separates a luminance signal Y and a carrier color signal C using an NT8C color television signal frame memory and line memory. An example of a diagram is shown.

In the NTSC system color television signal, the polarity of the carrier color signal C is reversed every horizontal scanning period H, and even in the signal of the scanning line at the same position on the screen one frame (525H) delayed, the C The polarity of is reversed. Assuming that the input television digital signal is Xo, the signal delayed by IH in the line memory is X-□, and the signal delayed by 525H in the frame memory is X-5□5, the carrier color signal C1 in the first signal processing circuit is as follows. Can be extracted. Here, %HBPF represents the transfer characteristic of a bandpass filter that extracts a signal in the carrier color signal band. On the other hand, in the second signal processing circuit, the carrier color signal C2 can be extracted as follows. Therefore, the desired carrier color signal C obtained by mixing C1 and C2 using the motion coefficient k is expressed by the formula (1):
By transforming (2) as follows, C= becomes −C,
It is calculated as +(1-k)C2. In FIG. 4, a carrier color signal is obtained by specifically calculating equation (3), and a luminance signal Y is obtained by subtracting this from the original NT8C signal.

That is, the NTS input to the input terminal 13
The C signal X0 is the signal X- delayed by IH in the line memory 14.
8, signal X delayed by 525H in frame memory 15
-525 is obtained.

The outputs of the line memory 14 and frame memory 15 are subtracted by the subtraction circuit 16, the subtraction result is multiplied by the coefficient circuit 17, and the addition circuit 18 adds it to the output of the line memory 14.
The operation in parentheses () in 3) can be realized. Therefore,
The output of the addition circuit 18 is subtracted from the input signal X0 by the subtraction circuit 19, multiplied by 1/2 by the coefficient circuit 20, and inputted to the bandpass filter 21 to extract only the components of the carrier color signal band. ) can be used to obtain the desired carrier color signal C.

Further, when the C signal is subtracted by the subtraction circuit 23 from a signal obtained by delaying the input NTSC signal by a time equal to the calculation delay time of the bandpass filter 21 in the delay circuit 22, a desired luminance signal Y subjected to motion adaptive processing is obtained.

In this embodiment, a difference signal between frames is obtained by a subtraction circuit 26, a frequency component of this is extracted by a low-pass filter 27, and the absolute value is taken by an absolute value circuit 28. The motion information in the signal is O1 in the still image part.
In the video part, the amplitude is proportional to the brightness change between frames. This motion information signal is stored in a read-only memory IJ (ROM).
) etc., a motion coefficient k is obtained in a register 30.

When the signal input to the input terminal 13 is a signal from a home VTR or the like, there is jitter in the signal due to mechanical time fluctuations in the vT, and a signal one frame before will not have a correct transmission phase relationship. Therefore, by observing the sum signal between the frames of the burst part, if there is no signal, it can be determined that a signal conforming to the NTSC standard color television system has been input, and if there is a significant signal in the sum signal, it is possible to It can be determined that the signal is from a home VTR or the like. In the embodiment shown in FIG. 4, an adder circuit 31 calculates a sum signal between frames, inputs this into a band pass filter 32, extracts a subcarrier signal component, and generates a gate signal indicating a burst signal period in an input signal. The gate circuit 33 gates only the burst portion using the gate signal obtained by the extraction circuit 37, the absolute value of which is taken by the absolute value circuit 34, the accumulation circuit 35 accumulates the burst period, and the value is calculated. By comparing with a predetermined value in the threshold circuit 36, if there is a significant signal, the register 3
Reset to 0 and force the motion coefficient k to 0. This makes it possible to perform YC separation calculations without using the output of the frame memory.

FIG. 5 shows another example of the embodiment in which the present invention is applied to a signal processing circuit that performs motion adaptive scanning line interpolation on an interlace scan television signal to convert it into a progressive scan television signal. In the same figure, the interlace-scanned television signal input to the terminal 38 is input to the line memory 39 for IH delay and the field memory 42 for 263H delay, and in contrast to the current signal ZQl, the interlace scanned television signal directly above the screen is The line signal 2' is obtained by the following motion-adaptive calculation. That is, the first signal processing circuit generates the interpolation signal Zt using the signal Z-263 of the previous field delayed by 263H, which is the scanning line at the same position.

z' yoz (4) On the other hand, the second signal processing circuit creates an interpolated signal 2/2 using the average value of the current signal Z0 and the signal Z-1 delayed by IH.

The interpolated signal Z' to be obtained is obtained by mixing Z'1 and Z'2 with the motion coefficient explained in the embodiment of FIG. 4 as shown in the following equation.

Z'=kZ'1+(1-k)Z'2 In FIG. 5, the addition circuit 40, 1/2 coefficient circuit 41, subtraction circuit 43,
A coefficient circuit 44 and an adder circuit 45 represent circuits that perform the calculation of equation (6) to obtain an interpolated signal 2'. Current scanning line signal z0
The time axis of the interpolated scanning line signal 2' is compressed to 1/2 by the time compression circuits 46 and 47, and the switching circuit 48 is switched for each time-compressed scanning line, and the horizontal scanning period is set to 1 at the terminal 49. /2, and a progressive scanning signal is obtained in which all the scanning lines are scanned during the field period of the input television picture signal.

The television signal input to terminal 38 is connected to a home VTR.
If it is a signal whose time axis has fluctuated from, etc., the register 50 is reset, the motion coefficient is forced to 0, and a line average interpolation signal is obtained as an interpolation signal.

In this embodiment, the presence or absence of time axis fluctuation is determined by extracting the vertical synchronization start signal of the television signal Z0 with an extraction circuit 51, and measuring the period of the vertical synchronization signal with a counter 52 that operates with a clock signal of the sampling frequency. The gate circuit 53 supplies the measured value of the vertical period to the determination circuit 54 . The determination circuit 54 determines that the signal conforms to the standard television system if the measured value is equal to a predetermined value. If they are not equal, it is determined that the signal does not conform to the standard method and has large time axis fluctuations, and the register 50 is reset.

In the above-described determination method of the embodiment shown in FIG. 5, in addition to color television signals of standard formats such as NTSC, monochrome television signals and color television signals of other formats (for example, component signals and color difference signals are time-compressed). It can also be applied to signals that are time-multiplexed with luminance signals).

In addition, when the judgment circuit of the embodiment shown in FIG. 4 and the judgment circuit of the embodiment shown in FIG. By switching to , a signal processing circuit that can handle a wider range of signal sources can be obtained.

Note that, as is clear from the configuration of the embodiment, the first and second signal processing circuits can share their common parts and arrange only substantially different parts side by side, thereby simplifying the circuit. is clear, and the specific configuration is not limited to the example.

In addition, in the embodiments shown in Figs. 2, 4, and 5, a judgment circuit is provided to automatically judge whether the input television signal conforms to the standard system or not. A method may be adopted in which a plurality of sets are provided and the signal input to a specific terminal is a signal that does not conform to the standard method, or a switching signal is manually applied from the outside.

Although the present invention has shown a YC separation circuit and a conversion circuit from an interlaced scanning signal to a sequential scanning signal as a specific example of a signal processing circuit having an image memory, the present invention is not limited thereto, It can be applied to encoding devices such as inter-coding and inter-field encoding, and to general circuits that generally have an image memory and perform signal processing, such as noise removal circuits.

In the embodiments of the present invention (FIGS. 4 and 5), the NTSC television signal has been described, but it is obvious that other systems (PAL% SECAM, etc.) are also applicable.

〔Effect of the invention〕

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

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle of the present invention, and FIGS. 2 to 5 are the actual embodiments of the present invention. A configuration diagram of example i is shown. 2.3...Signal processing circuit, 4,33,48.53...
・Switching, switching (gate) circuit, 7...judgment circuit, 10...
・Motion detection circuit, 14.39...Line memo 1c 1
5...Frame memory, 16.18.19.23,2
6゜31.40,43.45...addition (subtraction) circuit, 1
7゜20.41.44...Coefficient circuit, 21.32...
・Band pass filter, 22...Delay circuit, 28.34
... Absolute value circuit, 29 ... Conversion circuit, 30.50.
...Register, 35...Accumulation circuit, 36...Threshold circuit, 37°51...Extraction circuit, 42...Field memory, 46°47...Time compression circuit, 52...
-Counter, 54...judgment circuit. 7ri

Claims (1)

[Claims] 1. In a signal processing circuit having an image memory having a delay time approximately equal to the vertical scanning period of a television signal or an integral multiple thereof, a first signal processing circuit having the image memory; a second signal processing circuit having no image memory, and a switching means for selecting the output of the second signal processing circuit when the television signal to be processed is not in a standard color television format. A television signal processing circuit comprising: 2. Claim 1, characterized in that a determination circuit is provided to determine whether or not the television signal to be processed is a standard color television signal, and the switching means is controlled by the output of the determination circuit. The television signal processing circuit described in . 3. In claim 1 or 2, if the switching means is comprised of a coefficient generation circuit, a coefficient multiplication circuit, and an addition circuit, and the television signal to be processed is not a standard color television signal, this applies. A television signal processing circuit characterized in that the coefficient value of the coefficient generation circuit output is forcibly set to a predetermined value so that the output of the second signal processing circuit can be obtained.