JPH0368297A - Video signal processing device - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution by providing a noise reduction circuit before a vertical interpolation circuit. CONSTITUTION:A reproduction video signal is fed to a reproduction signal processing circuit 6, where time axis correction is applied to obtain a luminance signal Y and line sequential color signals PS/PN, a noise reduction circuit 7 eliminates a noise component and a vertical interpolation circuit 8 obtains the color signals PS, PN. The color signals PS, PN and the luminance signal Y are converted into analog data from digital data by D/A converters 9a-9c and a reproduction video signal whose noise is reduced is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal processing device that processes color signals line-sequentially, and relates to noise reduction therein.

[Conventional technology]

The high-definition TV system that has been developed as the next generation TV system and is being put into practical use is approximately 20MH2
It has a wide video signal band.

As a method of transmitting video signals in a system having such a wide video signal band, there is a method of processing color signals line-sequentially. Here, line sequential processing means that in one frame, P
By extracting only the odd-numbered scanning lines from l and only the even-numbered scanning lines from P and t, they are converted into a one-channel color signal Pa/Pa, and the amount of information of the color signal is reduced by half.

This is shown in FIG. 4. FIGS. 4(a) and 4(c) show the two-channel color signal PlrPl, FIG. 4(c) shows the line-sequentially processed color signal Pa/Pa, and FIG. ) is the above P
g, Pa, and the luminance signal Y corresponding to P l /PR.

In the figure, the subscript after the luminance signal Y, line sequential color signal Pa/Pa, color signal P, , P indicates the scanning line number within the frame, and IH indicates one horizontal scanning period. It is something. At this time, when viewed in the vertical direction, line-sequential processing of color signals means that the sampling frequency (horizontal scanning frequency) is halved, so in order to prevent vertical aliasing distortion, a vertical LPF is is limited.

As an apparatus that performs such signal processing, a magnetic recording/reproducing apparatus F (hereinafter referred to as VTR) that employs a multi-channel multi-segment recording method will be described below.

This method uses multiple channels to reduce the signal bandwidth per channel, and multi-segmentation increases the relative speed between the rotating head and magnetic tape to lengthen the recording wavelength. It records signals.

Here, with reference to FIG. 2(a), a reproduction system of a VTR using a 24-channel 3-segment recording system in which color signals are recorded and reproduced by line-sequential processing will be explained.

In FIG. 2(a), 1 is a magnetic tape which is a recording medium. The two-channel signal processing system is CH and A, respectively.
, CHoB, 12a and 12b are rotary heads for recording and reproducing signals of CH and A, 13a and 13b are signals of CHoB, 3a and 3b are head amplifiers, 4a
, 4b is an FM demodulation circuit that demodulates the reproduced FM signal, and 5a.

5b is A that converts analog data into digital data
/D converter, 6 is time base correction (TBC).

A reproduced signal processing circuit outputs a luminance signal Y that has undergone time axis correction by performing channel bottom correction, etc., and a color signal that has been line-sequentially processed (referred to as a line-sequential color signal) P, /P; 10 is a line-sequential color signal; Vertical interpolation circuit for restoring color signals PI, PR from signals Pg /P, ++, 11a, llb are color signals PI, P
Noise reduction circuit for removing noise components of each R, 9
a, 9b, and 9C are D/A converters that convert digital data into analog data.

Next, the operation will be explained.

In this conventional example, the signals reproduced from the magnetic tape 1, which is a recording medium, from the heads 12a and 12b for CH and A, and the heads 13a and 13b for CH1B are arranged on the time axis as shown in FIG. It is assumed that the signal is a two-channel signal that has been converted and multiplexed.

Here, time axis conversion multiplexing compresses the time axis of the line-sequential color signal for each signal of one horizontal scanning line, while expanding the time axis of the luminance signal divided into two channels for each signal of one horizontal scanning line. , Pmn0 and Yno (no is an odd number), Plne and Y
ne (ne is an even number) are time-division multiplexed to obtain two-channel signals Pl-YCH,A and P, -YCH,B.

This signal is amplified by head amplifiers 3a and 3b, and then FM demodulated by FM demodulation circuits 4a and 4b. After the analog data is converted into digital data by the A/D converters 5a and 5b, time base correction (TBC) is performed by the playback signal processing circuit 6, and then the two-channel playback video signal is time-base conversion multiplexed. The luminance signal Y and line sequential color signals PI/PI (FIG. 4(C)) are restored from (FIG. 3).

This line sequential color signal Pg/Pm is processed by the vertical interpolation circuit 8.
The color signals P, pl are restored as shown in Figures (a) and (b). In this way, the time axis of the color signal is expanded in the process of recording, reproducing, and outputting the time axis in a compressed state.
Compared to the Y signal, noise tends to concentrate in the low frequency range.

Here, noise reduction circuits 11a and 11b are provided to remove two noise components from each of the color signals P, , P.

An example of this noise reduction circuit is shown in FIG. This noise reduction circuit is a circuit that uses a limiter to extract a noise component from a high-frequency signal of a video signal, and reduces the noise component by subtracting it from the original signal.

Thereafter, the luminance signal Y and the color signals Pm, Pm are converted into analog data by the D/A converters 18a, 18b, 18c to obtain a reproduced video signal in which the noise of the color signal is reduced.

In addition, as another conventional example, as shown in FIG. 2(b), A/
Even if noise reduction is performed on a time-base converted multiplexed signal that has undergone D conversion, it is possible to obtain a reproduced video signal in which color signal noise is reduced.

[Problem to be solved by the invention]

Noise reduction for color signals in the reproduction system of a conventional magnetic recording and reproducing device that processes color signals line-sequentially is achieved by reducing the noise of each color signal PIl, P after vertical interpolation processing as shown in Figure 2.
, l, there was a problem in that two identical circuits were required.

This invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide a video signal processing circuit in which two noise reduction circuits for color signals are combined into one.

[Means for Solving the Problems] A magnetic recording and reproducing device that processes color signals line-sequentially according to the present invention performs noise reduction on color signals on line-sequential color signals PI/PR before performing vertical interpolation processing. This is how it was done.

(Function) With the above configuration, the effect can be obtained with one noise reduction circuit for color signals, which was required to have two circuits.

〔Example〕

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

As an example, a VTR that employs a two-channel three-segment recording method will be described. FIG. 1 is a block diagram of a reproduction system of a VTR according to the present invention. 1 is a magnetic tape which is a recording medium. The two-channel signal processing system is CH and A, respectively.
, CH, B, 12a and 12b are rotary heads for recording and reproducing signals of CH and A, 13a and 13b are rotary heads for recording and reproducing signals of CH and B, respectively, 3a and 3b are head amplifiers, 4a,
4b is an FM demodulation circuit that demodulates the reproduced FM signal, 5a and 5b are A/D converters that convert analog data to digital data, and 6 is a luminance signal that performs time base correction (TBC), channel synthesis, etc. Y1 line sequential color signal P l
7 is a line-sequential color signal P, a noise reduction circuit that removes the noise component of /P; 8 is a line-sequential color signal P-/P from which noise has been removed;
From *, the color signal Pl.

Vertical interpolation circuits 9a, 9b, and 9c restore Pl, and D/A converters convert digital data into analog data.

Next, the operation of the reproduction system shown in FIG. 1 will be explained.

A reproduced video signal reproduced from the magnetic tape 1 using the rotary heads 2a, 2b is amplified by the head amplifiers 3a, 3b, and then FM demodulated by the FM demodulation circuits 4a, 4b. Then, after being converted into digital data by A/D converters 5a and 5b, it is sent to the reproduction signal processing circuit 6. Here, a time base correction (TBC) operation is performed, and the time base conversion multiplexed two-channel playback video signal (the third
Figures (a) and (cb)) show a luminance signal Y and a line-sequential color signal P.

/PII (Figure 4(C)(d)) is obtained. Here, a noise reduction circuit 7 removes noise components from the line sequential color signals P and /Py. An example of this noise reduction circuit is shown in FIG. The line-sequential color signals P l / P R from which noise components have been removed are processed by a vertical interpolation circuit 8 into color signals Ps,
P+l (FIGS. 4(a) and (b)) is restored.

These color signals P, P and luminance signals Y are sent to the D/A converter 9a.
, 9b and 9c, the digital data is converted into analog data to obtain a reproduced video signal with reduced color signal noise. In this way, when noise reduction is applied to the color signal,
Although two noise reduction circuits are required, if noise reduction is performed on line-sequential color signals, only one noise reduction circuit can produce the same effect as the conventional example.

Although the above embodiment describes a VTR that employs a 2-channel 3-segment recording method, the same method as in the above embodiment applies to all video signal processing devices that perform line-sequential processing on color signals such as MUSE signals. The present invention can be configured as follows, and the same effects as those described above can be achieved.

Further, in the above embodiment, an example of a horizontal noise reduction circuit for reducing color signal noise is shown in FIG. 5, but the circuit is not limited to this. Any circuit configuration may be used.

[Effects of the Invention] As described above, according to the present invention, when reducing noise in color signals, the noise reduction circuit is provided before performing vertical interpolation so as to reduce noise in line-sequential color signals. This provides the same effect as when one noise reduction circuit is provided for two channels, and has the effect of simplifying the circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a reproduction system of a 2-channel 3-segment recording VTR according to an embodiment of the present invention, FIG. 2 is a block diagram of a reproduction system of a conventional 2-channel 3-segment recording VTR, and FIG. 4 is an operational explanatory diagram for explaining the operation of a reproduction system of a VTR according to an embodiment of the present invention, and FIG. 5 is a diagram showing a noise reduction circuit for reducing noise in color signals. 6... Reproduction signal processing circuit, 7... Noise reduction circuit,
8... Vertical interpolation circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a video signal processing device that performs line-sequential processing on a color signal and transmits it in the process of transmitting a video signal, a noise reduction means that performs noise reduction in the state of a one-channel line-sequential color signal; 1. A video signal processing device comprising a color signal restoring means for restoring the original color signal from the line-sequential color signal.