JPH01157178A - Characteristic correcting device - Google Patents

Abstract

PURPOSE:To cause level correcting operation to be exact by using a reproducing reference pulse, which has a pulse width, and pulse height data, which are quantizing data, preparing a level correcting table and level-correcting a reproducing video signal. CONSTITUTION:A reference pulse generating means 2 generates the plural types of the reference pulses, whose height is different, corresponding to the black level up to white level of the video signal and a pulse height data generating means 3 generates the pulse height data to be the quantizing data. Then, reference data and the pulse height data, which form a pair, are inserted to a recording video signal by a reference data inserting means 4. At a reproducing time, with using the reproducing reference pulse and the pulse height data to be obtained from the reproducing video signal by a gate pulse generating means 1 and a reference pulse selecting signal 6, a level correcting means 8 prepares the level correcting table and the level correcting operation is executed to read a value from the level correcting table, etc., with the output data of a reproducing A/D converter as an address. Then, the reproducing video signal, which is D/A converted by a reproducing D/A converter 9 and level-corrected, is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention automatically corrects distortion caused by nonlinearity of a signal processing system during recording and playback and corrects the playback signal level in a signal recording device. The present invention relates to a characteristic correction device for correcting characteristics.

[Conventional technology]

In signal recording devices such as VTRs, channel division recording is a method for recording wideband signals by dividing one signal into multiple channels to reduce the bandwidth required for each channel. There is a method.

In such a method, if the signal to be recorded is a television signal, the signal is divided into multiple horizontal scanning periods, distributed to multiple channels, and the distributed signals are time-extended and recorded. is used.

An example of this method is shown in FIG. 9, in which the input video signal is distributed to two channels (A, B). In the same figure (al indicates an input signal, and numbers are given in chronological order as Hl, H2, H3, etc. for each horizontal scanning period.The input signals are channel A and channel B for each horizontal scanning line. At the same time, it is subjected to time axis expansion and converted into the recording signal format shown in FIG. 9(b).

When the time axis of the signal is expanded by channel division in this way, the band for each channel decreases, but
Since one signal will be recorded and played back in two systems,
If there is a difference in characteristics between the channels, this leads to deterioration of the reproduced image quality, such as scanning lines becoming conspicuous in the above example. Therefore, a device that automatically corrects the characteristic difference between channels is required.

V that performs channel division and records and plays back as described above.
An example of the configuration of a characteristic correction device used in a TR is given in "Kiyoshi Sasaki et al.: Bandwidth Compression High-Vision VTR, National Technical Report Vol. 32 No.
4 J. Figure 1) is a block diagram showing the configuration of this device. In the figure, αO) is a memory for storing the reproduced lamp signal, αυ is an averaging and checking circuit that averages and checks the reproduced lamp signal, Sub is level correction table memory, (2) is reference lamp signal data memory, αa is a data processing circuit, 0 is a switch for switching the address of level correction table memory sub, 0ω
is the reproduction signal input terminal, αη is the reproduction lamp signal input terminal,
The α line is a time axis data terminal, and the 0 line is a correction output terminal.

The conventional characteristic correction device is configured as described above, and records a ramp signal that changes from a black level to a white level within a vertical blanking period of a video signal.1. : By playing back the data, a correspondence is created between the recording level and the playback level. When the ramp waveform shown in FIG. 10 (al) is recorded, if a distorted waveform as shown in FIG. By correcting the time axis and matching the timing with the ramp signal during recording, the input signal level and reproduction output level are made to correspond.

To explain this operation in detail, the reproduced ramp signal is first input to an averaging and checking circuit (Ql), where a plurality of reproduced ramp signals are added together to improve the S/N ratio, and the averaged reproduced ramp signal is Check the shape of the signal and remove effects such as dropouts. The reproduced lamp signal subjected to the averaging and shape checking is stored in the reproduced lamp data memory aω using the time axis data as an address. Next, the data and address of the reproduction lamp data memory α0) are reversed, and the level correction table memory (2) is stored.
to be memorized. The reference lamp signal data memory α stores the shape of the lamp signal at the time of recording, and if reproduced video signal data is given as the address of the level correction table memory (2) via the switch α, then the reference lamp The address of the signal data memory α is determined, and level-corrected video signal data is obtained at the output of the reference lamp signal data memory α■.

[Problem that the invention seeks to solve]

Since the conventional characteristic correction device is configured as described above, the timing of the ramp signal during recording and the ramp signal during playback must be perfectly matched, so a very high precision time base collector device is required. This is necessary, and if there is a time axis fluctuation within a period called velocity error, the timing cannot be perfectly matched between recording and playback in the second half of the horizontal period, and recording There was a drawback that the correspondence between the level and the playback level could not be established correctly.

Furthermore, if the video signal level is at the same level for a short period of time, such as the lamp signal used in conventional equipment, incorrect reproduced lamp data will be captured if the sampling position shifts, making it impossible to perform correct level correction operations. The problem was that there was no.

This invention was made in order to solve the problems of the conventional ones as described above, and its purpose is to provide a characteristic correction device that can correctly perform level correction operations even in a signal recording device that does not have a time base collector device. shall be.

Means for Solving Problem c] The characteristic correction device according to the present invention includes a reference pulse generating means that generates a plurality of types of pulses having different heights corresponding to at least the black level to the white level of a video signal; Pulse height data generating means for generating data for identifying the height of the output pulse of the pulse generating means; and reference data for inserting a pair of reference pulses and pulse height data into a blanking period of a recorded video signal. The apparatus is provided with an insertion means and a level correction means for level-correcting the reproduced video signal using a reference pulse and pulse height data obtained from the reproduced video signal.

[Effect]

In this invention, since the reference pulse has a time width, even if the reproduced video signal includes time axis fluctuations, by sampling and holding the vicinity of the center of the reference pulse, the pulse height at the time of reproduction can be determined. .

Further, since the pulse height data is quantized data, its value does not change even if it is subjected to distortion.

Therefore, it is possible to accurately associate the plurality of pulses of different heights corresponding to the range from the black level to the white level inserted during recording during recording and during playback.
Even in a signal recording device that does not have a time base corrector device, level correction can be performed correctly.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a characteristic correction device according to an embodiment of the present invention, in which reference pulses of 256 heights corresponding to the number of quantization levels of an 8-bit regenerative A/D converter and pulse height data in serial format are used. An example of inserting one set at a time during the vertical blanking period will be explained.

FIG. 1 shows a recording system block of this embodiment. In the figure, (1) is a gate pulse generating means for separating vertical and horizontal synchronizing signals from a recorded video signal and generating gate pulses, and (2) is a gate pulse generating means. A reference pulse generating means generates reference pulses of 256 different heights from black level to white level according to the output of the generating means (1), and (3) identifies the height of the output pulse of the reference pulse generating means (2). (4) is a reference data inserting means for inserting a pair of reference pulse and pulse height data into the vertical blanking period of the recording video signal.

FIG. 2 shows the reproduction system block of this embodiment, and in the figure, (5) is a reproduction A/D converter for A/D converting the reproduced video signal.
D converter, (6) is a reference pulse selection means for selecting the data of the reference pulse inserted during recording from the output data of the reproduction A/D converter (5), and (7) is a reference pulse selection means for selecting the data of the reference pulse inserted at the time of recording from the output data of the reproduction A/D converter (5); Selecting pulse height data selection means (8
) is a level correction means for level-correcting the reproduced video signal using the output data of the reference pulse selection means (6) and the output data of the pulse height data selection means (7), and (9) is the level-corrected video signal. This is a reproducing D/A converter that converts the data into D/A. It should be noted that the gate pulse generating means can also be used for the recording system, but it is of course possible to use another circuit that operates in exactly the same way.

Next, the operation will be explained using FIGS. 1 to 6. In FIG. 1, gate pulse generating means (1
) is a gate that separates the vertical and horizontal synchronization signals from the recorded video signal (see Figure 3(a)) and becomes high in one horizontal period after three horizontal periods from the vertical synchronization signal (see Figure 3(b)). A pulse (see FIG. 3 (C1)) is generated.

The reference pulse generating means (2) generates a gate pulse (Fig. 4(a)
)), first of all, 256/2
R
This occurs when data is read from the OM (see FIG. 4(b)). And pulse height data generation means (
3) generates pulse height data in serial format indicating the height of the reference pulse (see Figure 4 (C1)). Thereafter, the reference pulse data (2
55/256°25 4/256. ..., 2
/256. Pulse height data corresponding to 1/256) is generated every vertical planking period (Fig. 4 (bl)
, (see C1). Then, when the pair of reference pulse and pulse height data are inserted into the recorded video signal by the reference data insertion means (4), an output signal as shown in FIG. 5 is obtained, and this output signal is passed through the recording circuit. recorded.

During playback, a playback A/D converter (5) performs A/D conversion on a playback video signal in which the vicinity of the white level has shrunk due to distortion, for example. At the same time, the gate pulse generating means (1) generates a reproduction gate pulse synchronized with the reproduced video signal including time axis fluctuation (see FIG. 6 (al). According to this reproduction gate pulse, the reference pulse selection means (6) ) is a reproduction reference pulse whose height has changed due to distortion from the output data of the reproduction A/D converter (5), and the pulse height data selection means (7) is a reproduction reference pulse whose height has changed due to distortion. Obtain pulse height data that can identify the pulse height during recording from the video signal (6th
(See figure (C)).

Next, in the level correction means (8), a level correction table is created by writing the corresponding pulse height data into the memory using, for example, the data of all reproduction reference pulses as addresses. D converter (5)
Perform level correction operations such as reading values from the level correction table using the output data of as an address, remove the reference pulse and pulse height data inserted during recording, and then
When the reproduction D/A converter (9) performs D/A conversion, a level-corrected reproduction video signal is obtained.

In the above embodiment, the reference pulse and pulse height data are inserted one set at a time in one horizontal period within the vertical blanking period, starting from the one with the highest pulse height. As shown in FIG. 7, only the reference pulse is inserted in one horizontal period and the pulse height is inserted in the next horizontal period.
Or, as shown in Figure 8, if a pair of reference pulse and pulse height data are to be inserted within the blanking period, for example, the pulse height data is inserted first and the reference pulse is inserted later, any pattern can be used. may also be used, and the same effects as in the above embodiment can be achieved.

In addition, in the above embodiment, corresponding pulse height data is written into the memory using the reproduction reference pulse data as an address.
In the normal video period, we have explained an example using the level correction method in which a corrected value is read using the output data of the reproduction A/D converter (5) as an address. The data difference is written to the memory as correction data, and during the normal video period, the playback A/D
The correction data is read out using the output data of the converter as an address, and the level is corrected by adding it to the output data of the reproducing A/D converter, or the level correction data is created using software using a microcomputer, and the level is corrected. Other level correction methods may be used, such as interpolating data when a discontinuous point occurs in the data.

Further, in the above embodiment, an example was explained in which binary pulse height data of high or low was used, but quantized data such as ternary data may also be used.

In addition, in the above embodiment, an example was explained in which the data of the reproduction reference pulse obtained during reproduction is used as is. Further effects can be expected by combining measures such as not using reproduction reference pulse data.

〔Effect of the invention〕

As described above, according to the present invention, a level correction table is created using a reproduction reference pulse having a pulse width and pulse height data which is quantized data, and the level of a reproduced video signal is corrected. Therefore, it is possible to obtain a characteristic correction device that can accurately perform a level correction operation even in a signal recording device that does not have a time base collector device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a recording system of a characteristic correction device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a reproduction system of a characteristic correction device according to an embodiment of the present invention, and FIG. 4, 5, and 6 are operation explanatory diagrams of an embodiment of the present invention, and FIG. 7. Fig. 8 is an explanatory diagram of the operation of another embodiment of the present invention, Fig. 9 is an explanatory diagram of the channel division recording method in the signal recording device, Fig. 10 is an explanatory diagram of the operation of the conventional example, and Fig. 1). 1 is a block diagram showing the configuration of a conventional characteristic correction device. In the figure, (2) is a reference pulse generation means, (3) is a pulse height data generation means, (4) is a reference data insertion means, (5) is a reproduction A/D converter, and (8) is a level correction means. It is. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A characteristic correction device that corrects the characteristics of a signal processing system when recording and reproducing video signals, which corresponds to at least the black level to the white level of the recorded video signal within the blanking period of the recorded video signal. A pair of reference pulse generation means for generating a plurality of types of reference pulses of different heights, and a pulse height data generation means for generating quantized data for identifying the height of the output pulse of the reference pulse generation means. a reference data insertion means for inserting the reference pulse and the pulse height data into a blanking period of the recorded video signal; A characteristic correction device comprising: level correction means for level correction of a signal. (2) The output data of the pulse height data generating means is:
2. The characteristic correction device according to claim 1, wherein the data is in a serial format. (3) The reference pulse is composed of pulses having heights corresponding to respective quantization levels of a reproduction A/D converter that A/D converts the reproduced video signal. A characteristic correction device according to range 1 or 2.