JPH0548931A - Noise reducing device - Google Patents

Abstract

PURPOSE:To reduce a noise in the condition of a TCI signal and to minimize the circuit scale. CONSTITUTION:An adder 65 subtracts the TCI signal of a front frame stored in a frame memory 41 from the TCI signal from a terminal 61. A coefficient unit 66 sets a coefficient KY to express the improvement of an S/N which is a noise reducing quantity to the brightness signal Y of the TCI signal. A coefficient unit 67 sets a coefficient KC to express the improvement of the S/N to color difference signals PB and PR of the TCI signal. A change-over switch 68 distributes the output of the adder 65 to the coefficient unit 66 or the coefficient multiplier 67 based on a control signal to express the brightness signal period and the color difference signal period from a terminal 62. An adder 69 subtracts the output of the coefficient unit 66 or the coefficient unit 67 from the TCI signal from the terminal 61 and supplies the subtracted result to the frame memory 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reducing device for reducing noise of a so-called TCI signal used when transmitting or recording a high-definition video signal.

[0002]

2. Description of the Related Art A noise reduction device (hereinafter referred to as NR: Noise Reduce
r) is to reduce noise by using the correlation between fields and frames. For example, a motion signal is detected based on the difference between frames of a video signal, and the level of this motion signal is calculated from the video signal. According to the above, a noise component, for example, a difference between frames is subtracted to remove noise included in the video signal, and so-called S / N (Signal to Noise ratio) is improved.

The NR is widely used in video signal transmission devices and recording / reproducing devices such as television receivers and video tape recorders (hereinafter referred to as VTRs), which are roughly classified into so-called composite signal states. There are known ones that reduce noise and those that reduce noise in the state of so-called component signals.

By the way, high-definition television (hereinafter referred to as "High Definition Television") is currently under development, and part of it is in the stage of practical application. Further, development of a device for transmitting a high-definition video signal (hereinafter referred to as a high-definition video signal) while maintaining its wide band high quality and a device for recording / reproducing is under way. For example, the luminance signal Y and the color difference signal P _B, P HD video signal supplied as _R, the luminance signal Y and the color difference signal P _B, so-called TCI signal time-base compressed multiplexed to P _R (Time Compressed Integration or TDM signal, Also referred to as)), a device for transmitting and a device for recording / reproducing is actively developed.

Now, the TCI signal will be briefly described. The TCI method is, for example, one horizontal scanning period (hereinafter 1
Luminance signal Y of line) and two color difference signals P _B (B
-Y) and P _R (RY) are time-axis compressed and time-division multiplexed on one line. Specifically, for example, since the color difference signals P _B and P _R have a narrower bandwidth than the luminance signal Y, they are not visually perceived as deterioration of image quality. After axial compression, the color difference signals P _B and P _R are time-compressed to 1/4 times, respectively, and then the color difference signals P _B and P _R are line-sequentially alternated for every other line and time-division multiplexed with the luminance signal Y. To do.

For example, in a video tape recorder (hereinafter simply referred to as a high-definition VTR) which records or reproduces a high-definition video signal using a magnetic tape as a recording medium, the luminance signal Y and the color difference signals P _B and P _R are supplied. The high-definition video signal to be recorded is time-axis compression-multiplexed as described above to form a TCI signal, and then the TCI signal for one field is divided into a plurality of tracks in order to record the wide-band high-definition video signal on a magnetic tape. And then record it.

Specifically, in a high-definition VTR, for example, the so-called drum rotation speed is quadrupled and the TC
The I signal is divided into two channels according to the difference in the color difference signals, and two heads record at the same time, that is, so-called segment recording and multi-channel recording are used together (in this case, four segments and two channels are recorded. ). Further, at the time of reproduction, the recorded TCI signal is reproduced, and this TCI signal is reproduced using the luminance signal Y and the color difference signals P _B and P.
After being separated into _R , each time axis is expanded and output.

[0008]

By the way, for example, a so-called FPU (Field Pick U) that transmits a high-definition VTR for recording / reproducing such a high-definition video signal as a TCI signal or a high-definition video signal as a TCI signal.
In the case of applying the above noise reduction device (NR) in order to reduce the noise generated during transmission or reproduction, the conventional device may not transmit the transmitted or reproduced TCI.
After the luminance signal Y and the color difference signals P _B and P _R are separated from the signal, noise reduction processing is performed on the obtained luminance signal Y and color difference signals P _B and P _R , respectively. That is, there is no concept of a composite signal obtained by frequency-multiplexing a luminance signal and a color difference signal in a high-definition video signal transmission device or a recording / reproducing device, and in the conventional device, a component signal (luminance signal Y, color difference signals P _B , P _R). In this state, noise is reduced and three NRs are required.

The present invention has been made in view of such circumstances, and for example, in an apparatus for transmitting and recording / reproducing a high-definition video signal as a TCI signal, noise can be reduced in the state of the TCI signal. As a result, it is an object of the present invention to provide a noise reduction device capable of reducing the circuit scale as compared with the conventional device.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a noise reduction amount for a luminance signal of a time axis compression multiplexed signal obtained by time axis compression multiplexing of a luminance signal and a color difference signal in one horizontal scanning period. First noise reduction amount setting means for setting, second noise reduction amount setting means for setting a noise reduction amount for the color difference signal of the time-base compression multiplexed signal, and the first noise reduction amount setting means.
Switching means for switching and selecting the noise reduction amount from the noise amount setting means and the noise reduction amount from the second noise amount setting means in the luminance signal period and the color difference signal period, and the noise reduction selected by the switching means. Noise reduction means for reducing the noise of the time-axis compression multiplexed signal based on the quantity.

[0011]

In the noise reduction device according to the present invention, the noise reduction amount is switched between the luminance signal period and the color difference signal period to reduce the noise of the time axis compression multiplexed signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a noise reduction device according to the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit configuration of a first embodiment of a noise reduction device to which the invention is applied, and FIG. 2 is a recording of a high-definition video tape recorder (hereinafter referred to as a high-definition VTR) to which the noise reduction device is applied. FIG. 3 shows the circuit configuration of the system, and FIG. 3 shows the circuit configuration of the reproduction system of this high-definition VTR.

First, a high-definition VTR will be described. In this high-definition VTR, for example, as shown in FIG. 2, a luminance signal Y and color difference signals P _B and P _R in one horizontal scanning period (hereinafter referred to as one line) are time-axis compression multiplexed (Time Compr.
essed integration), the obtained so-called TCI signal is subjected to modulation suitable for recording, and then the recording heads 18A, 18
A recording system for recording on the magnetic tape 1 by dividing it into a plurality of tracks by B, and a luminance signal Y and a color difference signal from the TCI signal reproduced from the magnetic tape 1 by the reproducing heads 31A and 31B as shown in FIG. It is composed of a reproduction system that separates P _B and P _R and extends them along the time axis, and outputs the obtained luminance signal Y and color difference signals P _B and P _R.

The recording system of the high-definition VTR has a luminance signal Y and color difference signals P _B and P _R as shown in FIG.
Low pass filters (hereinafter referred to as LPFs) 11 _Y , 11 _B and 11 _R and analog / digital (hereinafter referred to as A / D) converters 12 _Y ,
12 _B and 12 _R , and the luminance signal Y converted into a digital signal from the A / D converter 12 _Y is divided into A channel and B channel for each line and time-axis expanded, and the A / D converter is provided. The color difference signals P _B and P converted into digital signals from 12 _B and 12 _R are divided into A channel and B channel for each signal and time-axis compressed, and the obtained luminance signal Y and color difference signals P _B and P _R are obtained. A TCI encoder 20 that forms a TCI signal by time-division multiplexing for each channel, and a digital / analog (hereinafter referred to as D / A) converter 13A that converts the TCI signal of each channel from the TCI encoder 20 into an analog signal. ,
13B and LPF 14A, 14B, and the LPF 14A,
The emphasis circuits 15A and 15B for applying so-called emphasis suitable for recording to the TCI signal of each channel converted to the analog signal from 14B, and the TCI signal of each emphasized channel from the emphasis circuits 15A and 15B, respectively, are so-called. FM modulating FM
Modulators 16A and 16B and the FM modulators 16A and 16B
A recording amplifier 17 that amplifies each FM-modulated recording signal from the recording medium and supplies it to the recording heads 18A and 18B, respectively.
It is composed of A and 17B.

Furthermore, the TCI encoder 20, as also shown in FIG. 2, the luminance signal Y from the A / D converter 12 _Y, for example, the odd lines to the A channel, 2 for the even lines and B-channel a change-over switch 21 for dividing the channel, the time axis expander 22A to each time-base-decompressed luminance signal Y of each channel from said changeover switching switch 21, and 22B, the a / D converter 12 _B, 12
Chrominance signals P _B from the _R, the P _R, with each filter in the vertical direction, for example, the color difference signal P _B of the odd lines in the A channel, the color difference signals P _R of the even lines B
A vertical filter 23 that is divided into two channels, time axis compressors 24A and 24B that compress the color difference signals P _B and P _R of each channel from the vertical filter 23 in the time axis, and the time axis expansion. 22A,
A frame memory 25 for storing the time-axis expanded luminance signal Y from 22B and the time-axis compressed color difference signals P _B and P _R from the time-axis compressors 24A and 24B, a so-called synchronization signal, a burst signal, etc. Synchronous signal generation circuit 26
And the sync signal from the sync signal generating circuit 26 is added (time division multiplexed) to the TCI signal of each channel read from the frame memory 25 (time division multiplexing).
Adder 27 for supplying to converters 13A and 13B, respectively
It is composed of A and 27B.

Further, the vertical filter 23 is also provided.
Is also shown in FIG.
2 _B, 12 color difference signals from _R P _B, the change-over switch 23a for selecting switching the P _R alternately every other line, 23b
And the output of the changeover switch 23a for two lines (2
A delay device 23c that delays the output of the changeover switch 23b by 1H, an adder 23e that adds the output of the changeover switch 23a and the output of the delay device 23c, and the adder 23e. Output of 1 /
A multiplier 23f for doubling, an adder 23g for adding the output of the multiplier 23f and an output of the delay device 23d, and an output of the adder 23g are multiplied by ½, and the color difference signal is filtered in the vertical direction. P _B is the A channel, and the color difference signal P
_{With R} as the B channel, the time axis compressors 24A, 2
4B and multipliers 23h respectively supplied to 4B.

In this recording system, for example, the luminance signal Y supplied via the terminals 2 _Y , 2 _B and 2 _R is time-divided by 3/2 to expand the color difference signals P _B and P _R , respectively. The color difference signals P _B and P _R obtained by respectively compressing the time axis by a factor of 1/2 are alternately line-sequential every other line to obtain 1
Luminance signal Y of odd line and color difference signal P _B of 1 odd line
Are time-division-multiplexed within two horizontal scanning periods and the T of A channel is
The CI signal is formed, and the luminance signal Y of one even line and the color difference signal P _R of one even line are time-division multiplexed within two horizontal scanning periods to form a TCI signal of B channel. That is, the luminance signal Y and the color difference signals P _B , P
For example, _R is time-axis compressed to 3/4 times and 1/4 times, respectively, and the time-axis-compressed color difference signals P _B and P _R are alternately line-sequentially arranged for every other line to obtain the luminance signal Y and time. It is divided and multiplexed, and the obtained TCI signal is divided into A channel and B channel according to the difference of color difference signals, and the same signal processing as that for one line of the divided TCI signal to be two horizontal scanning periods is performed. Is becoming Then, after adding a synchronizing signal or the like to the TCI signal of each channel, the signal is FM-modulated and the T-signal of each FM-modulated channel is added.
The CI signal is divided into, for example, four tracks on the magnetic tape 1 by so-called segment recording in which a video signal for one field is divided into a plurality of tracks and recorded.

Specifically, the A / D converter 12 _Y digitally processes the luminance signal Y supplied through the terminal 2 _Y and the LPF 11 _Y which is a prefilter by using a sampling clock of, for example, 44.55 MHz. Converted to signal, A /
The D converters 12 _B and 12 _R supply the color difference signals P _B and P _R supplied via the terminals 2 _B and 2 _R and the pre-filters LPF 11 _B and 11 _R , respectively, for example to 11.375.
It is converted into a digital signal by using a sampling clock of MHz. Then, the luminance signal Y and the color difference signals P _B and P _R converted into these digital signals are supplied to the TCI encoder 20.

Changeover switch 21 of TCI encoder 20
_Divides the luminance signal _Y from the A / D converter 12 _Y into two channels, for example, an odd line into an A channel and an even line into a B channel, and the A channel luminance signal Y into a time axis expander 22A. , B channel luminance signal Y
Is supplied to the time axis expander 22B.

The time axis expanders 22A and 22B are composed of, for example, a so-called FIFO (First In First Out) memory, and the time axis expander 22A is a luminance signal Y of the A channel.
Is stored once, and then read out at a clock of, for example, 29.97 MHz, that is, the time axis is extended to approximately 3/2 times,
Similarly, the time axis expander 22B expands the luminance signal Y of the B channel about 3/2 times. Then, the time-axis expanded luminance signal Y is stored in the frame memory 25.
Supply to.

On the other hand, the vertical filter 23 of the TCI encoder 20 filters the color difference signals P _B and P _R from the A / D converters 12 _B and 12 _{R in the} vertical direction, and, for example, the color difference signals of odd lines. P _B is divided into A channels, the even line color difference signal P _R is divided into B channels, and the A channel color difference signals P _B are divided into the time axis compressor 24A and the B channel color difference signals P _R are divided into the time axis compressor 24B. Supply to.

Specifically, the changeover switch 23a of the vertical direction filter 23 alternately selects and selects the color difference signals P _B and P _R from the A / D converters 12 _B and 12 _R every other line to select the delay device. 23c, the changeover switch 23b,
A / D converter 12 _B, 12 chrominance signals P _B from _R, P _R
Are alternately switched and selected every other line in an order different from that of the changeover switch 23a and supplied to the delay device 23d. As a result, for example, the delay unit 23c, the color difference signals P _R of the color difference signal P _B and odd lines of the even lines lines are sequentially supplied to the delay unit 23d, the color difference signal P _B of the odd lines and even lines The color difference signal P _R is line-sequentially supplied.

The delay device 23c delays the color difference signals P _B and P _R , which are line-sequentially supplied from the changeover switch 23a, by 2H, and the delay device 23d is the color difference signal P _B which is line-sequentially supplied from the changeover switch 23b. the P _R is the 1H delay.

Then, the adder 23e to the multiplier 23h are
After adding the output of the changeover switch 23a and the output of the delay device 23c, the output is multiplied by 1/2, and the output of the delay device 23d is added to the multiplication result, and then by multiplying by 1/2. adding the respective quarter of the signal P 1/2 and two even-numbered lines of the color difference signal P _B adjacent thereto of _B, also two odd lines 1/2 and adjacent to the color difference signals P _R of the even lines 1 for each color difference signal P _R
The color difference signals P _B and P _R are filtered in the vertical direction by adding / 4, that is, by obtaining the weighted average in the vertical direction. Then, the color difference signal P _B of the odd line filtered in the vertical direction is supplied to the time axis compressor 24A as the A channel, and the color difference signal P _{R of the} even line is supplied.
Is supplied to the time axis compressor 24B as the B channel.

The time axis compressors 24A and 24B are, for example, FI.
The time axis compressor 24A is composed of an FO memory and the like.
The color difference signal P _B of the channel is once stored and then read out at a clock of, for example, 29.97 MHz, that is, the time axis compression is performed to approximately 1/2, and the time axis compressor 24 B similarly performs the color difference signal of the B channel. P _R is approximately 1/2 times compressed on the time axis. Then, these time-axis compressed color difference signals P _B and P _R are supplied to the frame memory 25.

The frame memory 25 is used by the time axis expander 22.
After temporarily storing the time-axis expanded luminance signal Y from A and 22B and the time-axis compressed color difference signals P _B and P _R from the time-axis compressors 24A and 24B, for example, 29.97M
Based on the read clock of Hz, the color difference signal P _B of the odd line and the luminance signal Y of the odd line are time-division multiplexed for each line and read as the TCI signal of the A channel, and the color difference signal P _R of the even line and the even line Luminance signal Y of each line is time-division-multiplexed and read as a B channel TCI signal, and at this time, for example, the TCI signal for one field is divided into a plurality of tracks and recorded by the segment recording described above. In addition, so-called shuffling for changing the writing order and the reading order is performed in the field so that the influence of so-called dropout of the magnetic tape 1 is not concentrated in one place on the reproduction screen, and the shuffled TCI signal is To adders 27A and 2 respectively
Supply to 7B.

The adders 27A and 27B add the TCI signal of each channel read from the frame memory 25 to the sync signal from the sync signal generating circuit 26, the burst signal, and each segment in the above-described segment recording, for example, four segments. A segment signal for identifying a segment is added to each, and the TCI signal of each channel to which these synchronization signals and the like are added is supplied to each of the D / A converters 13A and 13B.

As described above, the TCI encoder 20 is
The luminance signal Y converted into a digital signal from the / D converter 12 _Y is line by line, for example, the luminance signal Y of an odd line.
To the A channel, and time-base-decompressed with dividing the luminance signal Y of the even lines in the B channel, also the A / D converter 12 _B, 12 color difference signals are converted into digital signals from _R P _B, the P _R Alternately every other line, for example, the color difference signals P _B of the odd lines are divided into A channels, and the color difference signals P _R of the even lines are divided into B channels, and time-axis compression is performed to obtain the obtained color difference signals P _B and P _R , respectively. The TCI of each channel is time-division multiplexed with the luminance signal Y of the same line.
It is designed to form a signal. Further, a synchronizing signal or the like is added to the TCI signal of each of these channels.

D / A converters 13A, 13B and LPF1
4A and 14B are adders 27 of the TCI encoder 20.
The TCI signals of the respective channels to which the synchronization signals and the like from A and 27B are added are converted into analog signals, and the TCI signals of the respective channels converted into these analog signals are supplied to the emphasis circuits 15A and 15B, respectively. As a result, the emphasis circuits 15A and 15B have
For example, as shown in FIG. 4, within two horizontal scanning periods (2H), the synchronization signal SYNC and the burst signal B are sequentially arranged from the beginning.
A, segment signal SEG, color difference signal C (P _B or P
_R ), and a TCI signal in which the luminance signal Y is time-division multiplexed.

The emphasis circuits 15A and 15B are LP
Emphasis suitable for recording is applied to the TCI signal of each channel converted into an analog signal from F14A and 14B, and FM modulators 16A and 16B perform FM modulation of the emphasized TCI signal of each channel, respectively. The recording heads 17A and 17B amplify the recording signals of the FM-modulated channels, respectively.
Supply to A and 18B.

By the way, the magnetic tape 1 is servo-controlled so that, for example, its running speed advances by 8 tracks within a time required to record a TCI signal for 1 field. By simultaneously recording the divided TCI signals of the respective channels by the recording heads 18A and 18B, the TCI signal for one field is divided into 8 tracks (4 segments, 2 channels) and recorded. In addition, this high-definition VTR
It has an audio system (not shown) for recording and reproducing audio signals,
For example, 4-channel analog audio signals are converted into so-called PCM signals, and these PCM signals are recorded on the same track by the same recording heads 18A and 18B as the video signals, and are recorded. The PCM signal is reproduced by reproducing heads 31A and 31B, which will be described later, and an audio signal is output.

Next, above as in the luminance signal Y and the color difference signal P _B, the high-definition video signal supplied as P _R, the luminance signal Y and the color difference signal P _B, TCI signal time-base compressed multiplexed to P _R A reproduction system of this high-definition VTR for reproducing a high-definition video signal from the magnetic tape 1 recorded as will be described.

The reproducing system of the high-definition VTR is, as shown in FIG. 3, described above, reproducing heads 31A and 31B for reproducing respective reproducing signals of A channel and B channel from the magnetic tape 1, and reproducing heads 31A and 31B. From the reproduction amplifiers 32A and 32B for amplifying the reproduction signals of the respective channels, and an equalizer (hereinafter referred to as EQ: Equalizer) 33A for equalizing the reproduction signals of the respective channels amplified from the reproduction amplifiers 32A and 32B. , 33
B, FM demodulators 34A and 34B for FM demodulating the equalized reproduction signals of the respective channels from the EQs 33A and 33B to reproduce the TCI signals of the respective channels, and the FM demodulators 34A and 34B. Channel TCI
De-emphasis circuits 35A and 35B that de-emphasis signals, and the de-emphasis circuit 35
LPFs 36A, 36B and A / D converters 37A, 37B for converting each channel's TCI signals supplied as analog signals from A, 35B into digital signals.
And a so-called time base correction circuit (hereinafter referred to as TBC: TimeBase corre) for correcting the time of the TCI signal of each channel converted into a digital signal from the A / D converters 37A and 37B.
ctor) 38 and the above de-emphasis circuit 35
A synchronization signal is detected from the TCI signal of each channel from A and 35B to pull in the synchronization of the TCI signal of each channel, and the A / D converters 37A, 37B and TBC
A synchronization detection circuit 39 for supplying a reproduction clock to 38 and the like;
The noise of the TCI signal of each channel corrected in the time axis from the TBC 38 is reduced, the luminance signal Y and the color difference signals P _B and P _R are separated from the TCI signal, and the luminance signal Y is compressed in the time axis to obtain the color difference. signal P _B, the color difference signals are alternately line sequentially every other line during the recording as well as extending axis P _R time P _B, the color difference signal P _B of all lines by the line interpolating P _R, P A TCI decoder 40 for reproducing _R , a ternary sync signal generating circuit 51 for generating a so-called ternary sync signal conforming to the Studio Standard of Broadcasting Technology Development Association (BTA), and a ternary sync signal generating circuit 51 Three
Adders 52 _Y , 52 _B and 52 _R for adding a value synchronization signal to the luminance signal Y and the color difference signals P _B and P _R reproduced by the TCI decoder 40, and the adders 52 _Y and 5
D / A converters 53 _Y , 53 _B , 53 _R for converting the luminance signal Y and the color difference signals P _B , P _R to which the ternary synchronization signals from 2 _B , 52 _R are added into analog signals and outputting the analog signals. It is composed of LPFs 54 _Y , 54 _B and 54 _R.

Further, as shown in FIG. 3, the TCI decoder 40 further includes a frame memory 41 for temporarily storing the TCI signal of each channel from the TBC 38 for deshuffling and the like, and the frame memory 41.
A noise reduction device 60 for reducing the noise of the TCI signal of each channel stored in the memory, and time axis compressors 42A, 42B for time axis compression of the luminance signal Y of each channel read from the frame memory 41. , A delay unit 43 for delaying the even-numbered line luminance signal Y supplied from the time axis compressor 42B as the B channel by 1H, and an odd-numbered line luminance signal Y supplied from the time axis compressor 42A as the A channel, The even-numbered line luminance signal Y delayed by 1H by the delay unit 43 is switched and selected for each line, and is added as the one-channel luminance signal Y by the adder 52 _Y.
Switch 44 for supplying to the frame memory 4 and
1. Color difference signals P _B and P _{R of} each channel read from
Axis extenders 45A and 45B for extending the
A delay unit 46 for delaying the color difference signal P _R of the even line supplied from the time axis expander 45B as the B channel by 1H, and the color difference signal P of the odd line supplied from the time axis expander 45A as the A channel. _B and the changeover switch 47 for switching and selecting the even line color difference signal P _R delayed by 1H by the delay unit 43 for each line, and outputting it as the line-sequential color difference signals P _B , P _R.
The color difference signals P _B and P _R, which are alternately supplied line-sequentially every other line from the changeover switch 47, are line-interpolated to form color difference signals P _B and P _R for all lines, and these color difference signals P _B and P _R are formed. _B and P _R are added to the above-mentioned adders 52 _B and 52
_It is composed of an interpolation circuit 48 which supplies _R to each.

Further, as shown in FIG. 3, the interpolation circuit 48 outputs the output of the changeover switch 47 to 1
A delay device 48a for delaying H, a delay device 48b for delaying the output of the changeover switch 47 by 2H, and a delay device 48b.
48c for adding the output of the selector switch 47 and the output of the changeover switch 47, a multiplier 48d for halving the output of the adder 48c, and the output of the multiplier 48d and the output of the delay device 48a for each line. Select switch 48
e and 48f.

The reproducing system of the high-definition VTR FM demodulates the reproduced signals of the A channel and B channel reproduced from the magnetic tape 1 by the reproducing heads 31A and 31B, respectively, and obtains the TCI of each channel.
Signal noise is reduced in the TCI signal state, and the luminance signal Y and the color difference signal (P _B or P _R ) for one line are time-axis compression multiplexed within two horizontal scanning periods as shown in FIG. The luminance signal Y and the color difference signals P _B and P _R are separated from the generated TCI signal, the luminance signal Y is compressed by 2/3 in the time axis, and the color difference signals P _B and P _R are extended in the time axis by 2 times. It is like this. Then, for example, the color difference signal P _B of the even line which is not reproduced and the color difference signal P _R of the odd line which are not reproduced because the recording is performed line by line alternately every other line at the time of recording, the color difference of the reproduced odd line. Signal P _B and even line color difference signal P _R by interpolation,
The color difference signals P _B and P _R and the luminance signal Y of all the obtained lines are output via the terminals 3 _B , 3 _R and 3 _Y , respectively.

Specifically, the reproducing heads 31A and 31B
Reproduces the reproduction signal from the magnetic tape 1 for each channel and supplies the reproduction signals of the A channel and the B channel to the reproduction amplifiers 32A and 32B, respectively.
A and 32B amplify the reproduced signals of the respective channels, EQs 33A and 33B equalize the reproduced signals of the respective amplified channels, and FM demodulators 34A and 34B.
Displays the equalized reproduced signal of each channel by FM.
It demodulates and reproduces the TCI signal of each channel. Then, the de-emphasis circuits 35A and 35B de-emphasize these TCI signals, respectively, and the LPF 36
Supply to A and 36B.

LPFs 36A, 36B and A / D converter 3
7A and 37B are de-emphasis circuits 35A and 35B
TC of each channel supplied as an analog signal from
Each of the I signals is converted into a digital signal, and these T
The CI signal is supplied to the TBC 38. The TBC 38 supplies the TCI decoder 40 with the time-axis corrected TCI signal of each channel that suppresses temporal fluctuations of the TCI signal, such as jitter, that occur during reproduction.

Noise reduction device 60 of TCI decoder 40
Reduces the noise of the TCI signal of each channel from the TBC 38 in the state of the TCI signal.

Specifically, the noise reduction device 60 is composed of, for example, a so-called recursive digital filter or the like, and is configured to reduce noise by utilizing the correlation between frames, for example, as shown in FIG. (The same circuits as those shown in the other figures are designated by the same reference numerals), terminal 6
1, an adder 65 for subtracting the TCI signal of the previous frame stored in the frame memory 41 from the TCI signal supplied through 1, and a noise reduction amount for the luminance signal Y of the TCI signal, for example, so-called S / N improvement. A coefficient unit 66 for setting a coefficient K _Y representing the degree, and color difference signals P _B , P of the TCI signal
A coefficient multiplier 67 for setting a noise reduction amount with respect to _R, for example, a coefficient K _C representing the degree of improvement of S / N, and the above addition based on a control signal representing a luminance signal period and a color difference signal period supplied via a terminal 62. A selector switch 68 for distributing the output of the multiplier 65 to the coefficient multiplier 66 or the coefficient multiplier 67, and the terminal 6
It is composed of an adder 69 for subtracting the output of the coefficient unit 66 or the coefficient unit 67 from the TCI signal supplied via 1 and supplying the subtraction result to the frame memory 41. Since the high-definition VTR of this embodiment uses two-channel recording, the circuit shown in FIG. 1 is required for two channels.

The noise reduction apparatus 60 subtracts the TCI signal of the previous frame stored in the frame memory 41 from the TCI signal supplied from the TBC 38 shown in FIG. The difference between the sync signal generation circuit 39 shown in FIG.
Based on the control signal supplied via 2, the luminance signal period is multiplied by the coefficient K _Y and the color difference signal period is multiplied by the coefficient K _C. Then, the noise of the TCI signal is reduced by subtracting the multiplication result from the TCI signal supplied via the terminal 61. For example, the level of the TCI signal supplied through the terminal 61 is TCI _IN, and the level of the noise-reduced TCI signal output through the terminal 63 is TCI _IN.
Given CI _OUT , the input / output characteristic (transfer function) and S / N improvement amount ρ of the noise reduction device 60 are represented by the following (1) and (2), respectively.

TCI _OUT = (1−K) Z ^−F / (1−KZ ^−F ) TCI _IN ... (1) ρ = 10 log (1 + K) / (1−K) ... (2)

However, Z- ^F represents one frame delay,
The above K is, for the luminance signal Y are coefficients K _Y, color difference signals P _B, for P _R is the coefficient K _C. by the way,
The respective values of the coefficients K _Y and K _C are generally visually such that the S / N ratio of the color difference signals P _B and P _{R is} , for example, 5 to 5 as compared with the luminance signal Y.
Since 6 dB is required to be good, it may be determined so.

In this way, the TCI signal whose noise has been reduced in the state of the TCI signal is deshuffled, separated into the luminance signal Y and the color difference signals P _B and P _R , and read from the frame memory 41. , The luminance signal Y is supplied to the time axis compressors 42A and 42B for each channel, and the color difference signals P _B and P _R are supplied to the time axis expanders 45A and 45B for each channel (for each signal).

The time-base compressors 42A and 42B have the luminance signal Y of each channel read from the frame memory 41.
And the delay unit 43 delays the time-axis-compressed luminance signal Y of the B channel, that is, the even-numbered line from the time-axis compressor 42B by 1H.

The change-over switch 44 switches and selects the luminance signal Y of the A channel from the time axis compressor 42A, that is, the odd-numbered luminance signal Y and the even-numbered luminance signal Y delayed by 1H by the delay unit 43 for each line. The luminance signal Y of one channel is supplied to the adder 52 _Y.

On the other hand, the time-axis expanders 45A and 45B respectively extend the color-difference signals P _B and P _R of the respective channels read from the frame memory 41 on the time axis, and the delay unit 46.
Delays the color-difference signal P _R of the time-axis expanded B channel, that is, the even-numbered line, from the time-axis expander 45B by 1H.

The changeover switch 47 selects, for each line, the color difference signal P _B of the A channel from the time axis expander 45A, that is, the odd line color difference signal P _B and the even line color difference signal P _R delayed by 1H by the delay device 43. Then, the interpolation circuit 48 outputs the line-sequential color difference signals P _B and P _R for one channel.
Supply to.

The interpolation circuit 48 line-interpolates the color difference signals P _B and P _R supplied as a line sequence from the changeover switch 47 to form color difference signals P _B and P _R of all lines, and these color difference signals P _B and P _R are formed. P _B and P _R are added for each signal by adders 52 _B and 52
Supply to _R.

Specifically, the delay unit 48 of the interpolation circuit 48
a and 48b delay the color difference signals P _B and P _R, which are line-sequentially supplied from the changeover switch 47, by 1H and 2H, respectively.

Then, the adder 48c to the changeover switch 48
e and 48f are the output of the delay device 48b and the changeover switch 47.
Output is added and then multiplied by ½, and the multiplication result and the output of the delay device 48a are alternately switched and selected for each line, so that, for example, line-sequentially alternate every other line during recording. For this purpose, the color difference signal P _B of the even line which is not directly reproduced from the magnetic tape 1 is formed by interpolation for obtaining the average value of two adjacent color difference signals P _B of the odd lines which are reproduced, and the odd color which is not reproduced. The color difference signal P _R of the line is converted into the color difference signal P _{R of the} even line to be reproduced.
Of the two adjacent ones are formed by interpolation. Then, the color difference signals P _B and P of all the obtained lines are obtained.
_R is supplied to each of the adders 52 _B and 52 _R for each signal.

The adders 52 _Y , 52 _B and 52 _R are TCI
The ternary synchronizing signal from the ternary synchronizing signal generating circuit 51 is added to the luminance signal Y and the color difference signals P _B and P _R from the decoder 40, and the D / A converters 53 _Y , 53 _B , 53 _R and L are added.
The PFs 54 _Y , 54 _B , and 54 _R are the luminance signal Y and the color difference signals P _B and P _R to which these three-valued synchronization signals are added, respectively.
Are converted into analog signals, and the luminance signal Y and the color difference signals P _B and P _R converted into these analog signals are output to, for example, a monitor receiver or the like via terminals 3 _Y , 3 _B and 3 _R , respectively. And at this time, as described above,
Since the noise of the luminance signal Y and the noises of the color difference signals P _B and P _R are reduced so as to be optimum, a reproduced image with an improved S / N can be obtained.

As described above, in the high-definition VTR of this embodiment, the noise of the reproduced TCI signal is reduced by switching the reduction amount during the period of the luminance signal Y and the period of the color difference signals P _B and P _R. This makes it possible to optimally reduce each noise of the luminance signal Y and the color difference signals P _B and P _R in the state of the TCI signal, and as a result, the luminance signal Y and the color difference signals P _B and P _R are separated. The noise reduction device 60 used in comparison with the conventional device that reduces the noise of each signal in the state
The number of can be reduced. For example, the number required in the past was three, but the number required for the high-definition VTR of this embodiment can be two. Furthermore, for example, in a high-definition VTR that does not perform 2-channel recording like this high-definition VTR but performs 1-channel recording, by applying the present invention, one noise reduction device can be provided. In other words, the circuit scale can be reduced and the cost can be reduced as compared with the conventional device.

Further, in this high-definition VTR, the frame memory 41 for deshuffling and the like can be used as the memory of the noise reduction device 60, and the parts can be saved.

Next, another embodiment of the noise reduction device according to the present invention will be described. FIG. 5 shows a circuit configuration of a second embodiment of a noise reduction device to which the present invention is applied, and FIG. 6 shows a circuit configuration of a third embodiment of a noise reduction device to which the present invention is applied. It is assumed that the noise reduction devices of these embodiments are also applied to the reproduction system of the high-definition VTR shown in FIG. 3, and redundant description will be omitted to continue the description.

The noise reducing apparatus 70 of the second embodiment comprises a recursive digital filter or the like, like the noise reducing apparatus 60 of the first embodiment, for example, and reduces noise by utilizing the correlation between frames. For example, as shown in FIG. 5, an adder 75 for subtracting the TCI signal of the previous frame stored in the frame memory 41 from the TCI signal supplied through the terminal 71, and the TCI signal A coefficient unit 76 that sets a noise reduction amount for the luminance signal Y, for example, a coefficient K _Y that represents the improvement degree of S / N, and a noise reduction amount for the color difference signals P _B and P _R of the TCI signal, for example, the improvement degree of S / N. A coefficient unit 77 for setting a coefficient K _C representing
A switch 78 for switching and selecting one of the outputs of the coefficient units 76 and 77 based on a control signal representing the luminance signal period and the color difference signal period supplied via the terminal 71.
From the TCI signal supplied via
It is composed of an adder 79 for subtracting the output of the coefficient unit 76 or the coefficient unit 77 selected in 7 and supplying the subtraction result to the frame memory 41.

The noise reduction device 70 subtracts the TCI signal of the previous frame stored in the frame memory 41 from the TCI signal supplied from the TBC 38 shown in FIG. The difference between them is multiplied by the coefficients K _Y and K _C , respectively. Then, based on a control signal supplied through the terminal 72 from the sync signal generating circuit 39 shown in FIG. 3 described above, from TCI signal supplied through the terminal 71, the luminance signal duration multiplied by the coefficient K _Y By subtracting the difference and subtracting the difference obtained by multiplying the coefficient K _C during the color difference signal period, noise of the TCI signal is reduced.

As a result, like the first embodiment described above,
The S / N improvement amount ρ shown in the above equation (2) can be obtained. That is, also in the noise reduction apparatus 70 of the second embodiment, the noise of the reproduced TCI signal is reduced by switching the reduction amount during the period of the luminance signal Y and the period of the color difference signals P _B and P _R. , TCI signal state, luminance signal Y
And the color difference signals P _B and P _R can be optimally reduced, and as a result, the luminance signal Y and the color difference signals P _B and P _B are reduced.
The number of noise reduction devices 70 to be used can be reduced as compared with the conventional device that reduces the noise of each signal with P _R separated.

Unlike the first and second embodiments described above, the noise reducing apparatus 80 of the third embodiment uses the correlation between pixels to reduce noise in the horizontal or vertical direction. For example, as shown in FIG. 6, a high pass filter (hereinafter referred to as HPF) 81 for extracting a high frequency component of the TCI signal supplied via a terminal 91, and the HPF 8
Limiter 82 for limiting the output level of 1 to a predetermined value or less
And a coefficient unit 83 for setting a noise reduction amount of the TCI signal with respect to the luminance signal Y, for example, a coefficient K _Y representing the degree of improvement in S / N.
And a coefficient unit 84 for setting a noise reduction amount for the color difference signals P _B and P _R of the TCI signal, for example, a coefficient K _C representing the degree of improvement of S / N, a luminance signal period supplied through a terminal 92, and a color difference. A changeover switch 85 for distributing the output of the limiter 82 to the coefficient unit 83 or the coefficient unit 84 based on a control signal representing a signal period, and a delay unit 86 for delaying the TCI signal supplied via the terminal 91. The delay device 86
It is composed of an adder 87 which subtracts the output of the coefficient unit 83 or the coefficient unit 84 from the TCI signal delayed by and outputs the result. By the way, when the noise is reduced in the horizontal direction, the delay amount of the delay device 86 is A / A shown in FIG.
One period of the sampling clocks of the D converters 37A and 37B is set, and it is set to 1H when noise is reduced in the vertical direction.

The noise reduction device 80 extracts the noise component of the TCI signal supplied from the frame memory 41 shown in FIG. 3 via the terminal 91, that is, the high frequency component, and the noise reduction effect becomes excessive. This high-frequency component is limited to a predetermined value or less so that the brightness is limited to the high-frequency component whose level is limited based on the control signal supplied from the synchronization signal generating circuit 39 shown in FIG. The signal period is multiplied by the coefficient K _Y , and the color difference signal period is multiplied by the coefficient K _C. Then, the noise of the TCI signal is reduced by subtracting the multiplication result from the TCI signal delayed by the delay device 86.

As a result, noise in the horizontal or vertical direction can be reduced in the TCI signal state. That is, the noise reduction device 80 of the third embodiment reduces the noise of the reproduced TCI signal by switching the reduction amount during the period of the luminance signal Y and the periods of the color difference signals P _B and P _R. , TCI signals, noises of the luminance signal Y and the color difference signals P _B and P _R can be optimally reduced in the horizontal direction or the vertical direction, respectively, and as a result, the luminance signal Y and the color difference signal P _B are reduced. , P _R are separated, the number of noise reduction devices 80 to be used can be reduced as compared with the conventional device that reduces the noise of each signal.

The present invention is not limited to the above-described embodiment, and for example, so-called for detecting a motion signal based on the difference between frames of a video signal and reducing noise according to the level of the motion signal. It goes without saying that the present invention can be applied to an adaptive noise reduction device and the like.

[0062]

As is apparent from the above description, according to the present invention, the noise of the time-axis compression multiplex signal obtained by time-axis compression-multiplexing the luminance signal and the color difference signal in one horizontal scanning period is reduced to the luminance signal period and the color difference signal. By switching and reducing the reduction amount during the period of, it is possible to optimally reduce the noise of the luminance signal and the color difference signal in the state of the time axis compression multiplexed signal. It is possible to reduce the circuit scale as compared with a conventional device that reduces the noise of the respective signals while separating the color difference signals.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a first embodiment of a noise reduction device to which the present invention is applied.

FIG. 2 is a block diagram showing a circuit configuration of a recording system of a digital video tape recorder to which the noise reduction device is applied.

FIG. 3 is a block diagram showing a circuit configuration of a reproduction system of a digital video tape recorder to which the noise reduction device is applied.

FIG. 4 is a diagram showing a format of a TCI signal.

FIG. 5 is a block diagram showing a circuit configuration of a second embodiment of a noise reduction device to which the invention is applied.

FIG. 6 is a block diagram showing a circuit configuration of a third embodiment of a noise reduction device to which the invention is applied.

[Explanation of symbols]

 41 ... Frame memory 65 ... Adder 66 ... Coefficient multiplier 67 ... Coefficient multiplier 68 ... Changeover switch 69 ... Adder

Claims (1)

[Claims] 1. A first noise reduction amount setting means for setting a noise reduction amount for a luminance signal of a time-axis compression multiplexed signal in which a luminance signal and a color difference signal in one horizontal scanning period are time-axis compressed and multiplexed, and the time-axis compression Second noise reduction amount setting means for setting the noise reduction amount for the color difference signal of the multiplex signal, the noise reduction amount from the first noise amount setting means, and the second noise reduction amount
Switching means for switching and selecting the noise reduction amount from the noise amount setting means of the luminance signal period and the color difference signal period, and reducing the noise of the time-axis compression multiplexed signal based on the noise reduction amount selected by the switching means. A noise reduction device comprising: