JPH0710112B2 - Color video signal reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a color video signal reproducing apparatus for reproducing a color video signal recorded on a recording medium from the recording medium.

[Conventional technology]

As a conventional color video reproducing apparatus, for example, a VTR can be raised. There are various kinds of correction processing of the reproduction signal performed when reproducing the color video signal from the recording medium on the reproduction side of the VTR, but here, the removal of noise generated during reproduction will be described. Conventionally, the noise removal is performed only on the reproduced luminance signal as described later.

FIG. 2 includes a noise removal circuit for luminance signals as a conventional example.
FIG. 3 is a diagram showing a schematic configuration of a VTR playback side.

In FIG. 2, a magnetic head 1 is used rather than a magnetic tape (not shown).
The reproduction composite video signal reproduced by a and 1b is supplied to the switching switch 2. The switching switch 2 is alternately switched between the A side and the B side in the figure by a head switching pulse generated according to the rotation cycle of the magnetic heads 1a and 1b, which are rotating heads, and the magnetic heads 1a and 1b are used. The reproduced reproduction composite video signal is supplied to the reproduction amplifier 3.
Incidentally, the switching switch 2 is adapted to switch every 1/60 seconds when it is compatible with, for example, an NTSC television signal.

The signal amplified by the reproduction amplifier 3 is supplied to a high-pass filter (HPF) 4, a low-pass filter (LPF) 5, and a known automatic frequency control (AFC) circuit 6, and a reproduction luminance signal is reproduced from HPF4 and reproduced by LPF5. The chroma signal is separated.

The reproduced luminance signal is demodulated by the FM demodulation circuit 7 and then supplied to the correlation detection circuit 8 and the subtracters 9 and 10.

On the other hand, the reproduced chroma signal is frequency-exchanged for reduction, and the form of the original chroma signal by the well-known frequency conversion circuit 11 and the bandpass filter (BPF) 12, that is, the signal modulated by the subcarrier fsc (3.58MHz). After being returned, it is supplied to the mixer 13. The AFC circuit 13, the automatic phase control (APC) circuit 14, and the sub-frequency conversion circuit 15 are well-known circuits that generate a signal for time-axis correction used when performing well-known frequency conversion in the frequency conversion circuit 11. It is what makes me.

Here, the noise removal of the luminance signal demodulated by the FM demodulation circuit 7 will be described.

In FIG. 2, the FM demodulated luminance signal is supplied to the correlation detection circuit 8 and is delayed by 1H by the 1 horizontal scanning period (H) delay circuit 16 described later in the correlation detection circuit 8.
Correlation determination calculation is performed with the noise-removed luminance signal of 1H before, and the setting of the value of the coefficient integrated in the coefficient integration circuit 17 described later is controlled according to the result. That is, in the coefficient integrating circuit 17, the coefficient value α is in the range of 0 ≦ α ≦ 1, for example, the stronger the correlation, the closer to α = 1, and the weaker the correlation α =.
It is set so as to be close to 0, and when it is determined that there is no correlation, α = 0.

As described above, after determining the correlation between the previous 1H and the present luminance signal and setting the coefficient α, the subtractor 9 subtracts the luminance signal delayed by the 1H delay circuit 16 from the present luminance signal,
The difference signal is input to the coefficient integration circuit 17, the coefficient α set as described above is integrated, and the integration result is supplied to the subtractor 10.

The FM demodulated current luminance signal reproduced as described above is supplied to the subtractor 10, and the subtractor 10 subtracts the output signal of the coefficient integration circuit 17 from the current luminance signal.

That is, when there is a strong correlation between the current luminance signal and the luminance signal delayed by 1H, it is considered that the difference signal output from the subtractor 9 has almost no noise component. The difference signal of the subtracter 9 is subtracted from the current luminance signal almost as it is, and when the correlation is weak, the noise component in the difference signal output from the subtractor 9 is considered to be small. The current luminance signal is output with almost no subtraction of the difference signal of the subtractor 9 from the current luminance signal. The luminance signal from which the noise component is adaptively removed in this way is supplied to the 1H delay circuit 16 and the mixer 13, and the 1H delay circuit 16 is delayed by 1H for the above-mentioned correlation detection, and the noise is similarly removed. Be done. Mixer
In 13, the luminance signal from which noise has been removed and the chroma signal whose frequency has been converted as described above are multiplexed and output as a reproduced composite video signal.

[Problems to be solved by the invention]

As described above, conventionally, the above-described noise removal was performed on the luminance signal, but the above-described noise removal was not performed on the chroma signal for the reason described below.

That is, the above noise removal is performed from the current signal using the past signal that is correlated with the current signal.
It is premised that a delay circuit or a one-frame period delay circuit is used.

However, as is well known, the chroma signal is a signal that is modulated by the sub-carrier fsc that has an interleaving relationship with the repetition frequency f _H of the horizontal scanning line. When the chroma signal and the past chroma signal are simply subtracted or added, the phase of the chroma signal is inverted every 1H, so the subcarrier fs is not processed unless the phase inversion is performed.
If the continuity of c is not maintained, and if the phase of the signal shifts due to the variation in the delay time of the delay circuit, it changes the hue, and there is a possibility that different color information may be restored.

For the above reasons, it is very difficult to remove noise using the delay circuit for the chroma signal by using the delay circuit unlike the luminance signal. Not used for
Other than the noise removal, no correction process that changes the phase was performed.

The present invention has been made in view of the above problems, and has a simple configuration for removing noise according to the correlation between the luminance signal and the carrier color signal in the color video signal reproduced from the recording medium, respectively. An object of the present invention is to provide a color video signal reproducing device capable of performing processing.

[Means for solving problems]

The color video signal reproducing apparatus of the present invention reproduces and outputs a color video signal stored in a recording medium, and a reproducing means for reproducing and outputting a luminance signal and a carrier color signal from the color video signal outputted by the reproducing means. The separating means for separating and outputting, and the luminance signal output from the separating means are inputted, and the noise eliminating processing according to the correlation degree of the inputted luminance signal is applied to the inputted luminance signal, and the luminance is outputted. A signal noise removing means and a converting means for converting the carrier color signal output from the separating means into a baseband color signal and outputting the baseband color signal, and a baseband color signal output from the converting means, and the input base A baseband chrominance signal noise eliminator for performing noise elimination processing on the band chrominance signal according to the degree of correlation of the luminance signal input to the first corrector, and outputting It is intended.

[Action]

With the above configuration, by converting the carrier color signal into the baseband color signal, it is possible to perform noise removal processing on the carrier color signal according to the degree of correlation of the luminance signal.

〔Example〕

 Hereinafter, the present invention will be described using examples.

FIG. 1 shows a VTR to which the present invention is applied as an embodiment of the present invention.
FIG. 3 is a diagram showing a schematic configuration of the noise removal circuit of FIG. In addition,
The same parts as those in FIG. 2 are designated by the same reference numerals.

In FIG. 1, as in FIG. 2, a reproduction luminance signal separated by the HPF4 among the reproduction composite composite video signals amplified by the reproduction amplifier 3 reproduced by the magnetic heads 1a and 1b from the magnetic tape (not shown). Is demodulated by the FM demodulation circuit 7, and then the correlation detection circuit 8 and the subtracters 9 and 10
Is supplied to.

Then, the correlation demodulation circuit 8 sets the coefficient α of the coefficient integration circuit 17 in the FM demodulated luminance signal in the same manner as described with reference to FIG. 2, and the noise removal of the luminance signal is performed in the same manner as in FIG. Done.

Further, since the reproduced chroma signal separated by the LPF4 from the reproduced composite video signal is reduced and converted, it is supplied to the color difference signal demodulation circuit 18 after being restored to the normal chroma signal by the same method as in FIG. It

The color difference signal demodulation circuit 18 converts the input chroma signal into R-
The color signals are demodulated into Y and B-Y color difference signals, and the chroma signals are demodulated into color difference signals to be demodulated into baseband signals having no information on the phase of the signals.

The noise removal of the RY and BY signals will be described below.

The RY signal demodulated from the chroma signal is a subtractor 19a,
Supplied to 19b. The subtractor 19a is supplied with the current R-Y signal and the 1H-preceding R-Y signal output from the 1H delay circuit 23. The subtractor 19a outputs the current R-Y signal and 1-H signal.
The difference signal of the R-Y signals before H is supplied to the coefficient integrating circuit 21. The coefficient integrating circuit 21 integrates the difference signal input similarly to the coefficient integrating circuit 17 with the coefficient β (0 ≦ β ≦ 1). The difference signal with the integrated coefficient β is supplied to the subtracter 19b. 1
In 9b, the difference signal multiplied by β is subtracted from the current RY signal to remove noise, and then supplied to the chroma signal modulation circuit 25 and also supplied to the 1H delay circuit 23 and then to the subtractor 19a.
The same operation is performed for the RY signal supplied to the.

For the BY signal, subtracters 20a, 20b and coefficient γ
Coefficient integrating circuit 22 for integrating (0 ≦ γ ≦ 1), 1H delay circuit
After the noise difference signal multiplied by γ is subtracted in the same manner as the RY signal and noise is removed by the 24, the chroma signal modulation circuit 25
Is supplied to.

As described above, since the chroma signal is demodulated into the RY and BY color difference signals, that is, the baseband signals, the coefficient integrating circuits 21 and 22 are provided.
By adaptively setting the coefficients β and γ in FIG. 2 in accordance with the correlation of the signals of RY and BY, respectively, by the method similar to the noise removal of the luminance signal as shown in FIG. The noise components of the -Y and BY signals can be removed, and the chroma signal generated in the chroma signal modulation circuit 25 from the color difference signals from which these noise components have been removed will have the noise components removed, and further mixing will occur. By being multiplexed with the luminance signal from which noise has been removed as described above in the device 13,
From the mixer 13, the output composite video signal from which the noise component is removed is obtained.

By the way, in the embodiment shown in FIG. 1, the coefficients β and γ of the coefficient integrating circuits 21 and 22 are set according to the strength of the correlation of the luminance signal determined by the correlation detection circuit 8 of the luminance signal. This is because the strength of the correlation between RY and BY is considered to correspond to the strength of the correlation of the luminance signal. That is, the stronger the correlation of the luminance signal is, the closer it is to β = 1, γ = 1, and the weaker the correlation is, the closer it is to β = 0, γ = 0.
Further, when it is determined that there is no correlation, β = 0, γ = 0
Becomes

Then, using the coefficients β and γ set according to the correlation of the luminance signal as described above, noise removal of the RY and BY signals is performed in the same manner as the luminance signal, and noise removal is performed.
-Y and BY signals are input to the chroma signal modulation circuit 25,
Here, after the RY and BY color difference signals are modulated into the original chroma signal form, they are multiplexed with the luminance signal in the mixer 13 and output as an output composite video signal.

As shown in FIG. 1 above, when the correlation detection circuit is provided only for the reproduction luminance signal, the correlation is detected, and the coefficient of each coefficient integrating circuit is set accordingly, the luminance signal, R
It is not necessary to provide a correlation detection circuit for each of the -Y signal and the BY signal. This is because the noise mainly occurs at the stage of the composite signal at the time of reproduction, and the luminance signal, the RY signal, and the BY signal separated from the composite signal show the same tendency to each other. In the case of noise removal utilizing the correlation of signals as in the example, correlation detection may be performed on any one of the luminance signal, the RY signal, and the BY signal, and it is set accordingly. By making the same coefficient for each signal, noise is removed from each signal having the same correlation tendency based on the same noise removal characteristic, which simplifies the device and reduces color shift at the time of restoration. It can be prevented from occurring. Further, in FIG. 1, the correlation detection circuit is provided for the luminance signal for which the correlation detection is particularly easy, but the correlation detection circuit is not limited to this and may be provided for either the RY or BY signal.

Further, in the present embodiment, it is assumed that the signal before 1H has a high correlation due to the nature of the image signal with respect to the current signal, so that noise is removed by using the 1H delay circuit, so that one field or one frame period is used. The noise can be removed with higher accuracy by using the delay circuit, field, frame memory, or the like.

Further, in this embodiment, the chroma signal is demodulated into the color difference signal to remove the noise. However, the present invention is not limited to this, and the noise removal is performed after demodulating to another baseband signal such as RGB three primary color signals. It goes without saying that you can do it.

Up to this point, the present invention has been described with reference to the preferred embodiment of the present invention as shown in FIG. 1. However, the present invention is not limited to this embodiment, and other than the noise removal, other than aperture control, etc. Can be applied to not only the VTR but also a reproducing device such as a video disk device.

〔The invention's effect〕

As described above, according to the present invention, with a simple structure,
It is possible to provide a color video signal reproducing apparatus that can perform noise removal processing on a luminance signal and a carrier color signal in a color video signal reproduced from a recording medium according to video correlation.

[Brief description of drawings]

FIG. 1 shows a VTR to which the present invention is applied as an embodiment of the present invention.
FIG. 3 is a diagram showing a schematic configuration of the noise removal circuit of FIG. FIG. 2 includes a noise removal circuit for luminance signals as a conventional example.
FIG. 3 is a diagram showing a schematic configuration of a VTR playback side. 8 ... Correlation detection circuit, 16, 23, 24 ... 1 horizontal period delay circuit, 17, 21, 22 ... Coefficient integration circuit, 18 ... Color difference signal demodulation circuit, 25 ... Chroma signal modulation signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Kouzuki 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Plant (72) Hiroji Takahashi 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Business Co., Ltd. (72) Inventor Katsuji Yoshimura, Kanagawa Prefecture, Kawasaki City, Takatsu-ku, 770 Shimonoge, Canon Inc. Tamagawa Business Office (56) Reference JP-A-57-160288 (JP, A) JP-A-61- 61593 (JP, A) JP 60-219888 (JP, A) JP 60-130293 (JP, A)

Claims (1)

[Claims] 1. A reproducing means for reproducing and outputting a color video signal recorded on a recording medium, and a luminance signal and a carrier color signal are separated from the color video signal outputted by the reproducing means and outputted. And a luminance signal noise removing means for inputting the luminance signal output from the separating means, performing noise removal processing on the input luminance signal according to the degree of correlation of the input luminance signal, and outputting the noise signal. A conversion means for converting the carrier color signal output from the separating means into a baseband color signal and outputting the baseband color signal, and inputting the baseband color signal output from the converting means, with respect to the input baseband color signal And a baseband chrominance signal noise removing means for performing noise removal processing according to the degree of correlation of the luminance signal input to the first correcting means and outputting it. Deo signal reproducing apparatus.