JPS6313589A - Still picture continuous peproducing system - Google Patents

Abstract

PURPOSE:To form data on a still picture whose S/N is improved by averaging still picture signals of several frames at the time of low speed reproducing mode. CONSTITUTION:At the time of low speed reproducing mode]a picture signal in a position where a head H-1 scanned one frame before a head H is positioned and a picture signal in a position where a head H+1 scanned one frame after the head H is positioned are fetched into an arithmetic circuit 14 through a time base correcting device 12. Data on added pictures are recorded in a frame memory 14C through an A/D converter 14A and an adder circuit 14B. A control signal outputted from a timing circuit 13 loads data in the frame memory 14C onto a divider circuit 14D. By dividing by three, for instance, data on the same pictures is averaged and outputted to a signal processing circuit 15.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides continuous still image playback that can improve the quality of one frame worth of still images output when a magnetic recording and playback device is set to low-speed playback mode. It is related to the method.

[Summary of the invention]

The continuous still image reproduction method of the present invention extracts only several frames of still image signals output from the vicinity of the just track of duplicate still image signals output when the low-speed reproduction mode is set. By averaging these several frames worth of static image signals using digital calculation means,
Still image data with a high S/N ratio is formed, and this still image data is sequentially output in accordance with a low playback speed.

[Conventional technology]

When recording dramas, news, etc. shot with a TV camera, etc., use the high-definition TV format () IDTS).
It is preferable that a high-definition magnetic recording/reproducing device edits a television signal produced by a computer, and performs film recording using the reproduced signal.

- Generally speaking, it takes several times to several lθ times the period of one frame of a television signal to print a still image for one frame on a film recording device (EBR). The image signal supplied to the recording device is required to be a signal output in a low-speed playback mode of the magnetic recording and reproducing device, that is, a continuous signal of still images.

In the case of a magnetic recording and reproducing device using a standard television system, for example, when playing back a magnetic tape recorded at a normal recording speed in a low-speed playback mode, the tape speed is lowered and the D
By accurately tracking the recording track with a T (dynamic tracking) head, a television picture signal without noise bars is reproduced, but in the case of high-definition magnetic recording and reproducing devices, as is well known, one frame This is because the television signals for 1 hour are recorded on four recording tracks formed diagonally on the magnetic tape.

During low-speed reproduction, it becomes difficult to reproduce the image signal accurately on the recording track, that is, in a just-track state using the DT head.

Therefore, the present applicant has proposed a tape recorder that can obtain high-quality slow-speed playback images in such a high-definition magnetic recording and playback device. (Japanese Patent Application No. 80-141317) As shown in FIG. 4, the invention of the above-mentioned application is based on a still image formed when this magnetic tape is played back with respect to the track angle θPB of the track TN recorded during normal playback. 12. Calculate the track angle φPB of the scanning track TS of the magnetic head.12. Low-speed reproduction is performed using a drum whose diameter is D=W/πsinφPB.

When magnetic recording and reproducing with such a drum diameter is used, a high-quality image signal that is always just tracked can be obtained even at low speed reproduction.As shown in FIG. Time base supplement 1 device (TBC
) 2 to remove the jitter component and store it in the frame memory means 4 controlled by the just track detection signal detected by the timing signal generator 3.

Furthermore, by capturing image data while extending the time axis using a control signal output from the film recording device 5, film recording can be performed without lowering the quality of a high-density television signal. Become.

[Problem that the invention seeks to solve]

By the way, such a low-speed magnetic reproducing device ideally can obtain low-speed reproduced images by continuously outputting high-quality still images, but when the recording track width is narrowed or the signal band is increased In such a case, a decrease in C/N cannot be avoided, and there is a problem in that the S/N of the reproduced image signal is largely dominated by noise caused by thermal noise of the reproduction circuit, noise due to running fluctuation loss, and the like.

The present invention has been made with the aim of alleviating such problems, and provides a continuous still image reproduction method that can further improve the quality of image signals during low-speed reproduction.

[Means for solving problems]

The still image continuous playback method of the present invention converts several frames of image signals output in a low-speed playback mode into digital image signals, and includes a memory means for sequentially adding and storing image data, and an output from this memory means. The image data is input to an average value data arithmetic circuit that divides the image data by the number of frames to be added, and the averaged still image data is sequentially extracted in accordance with the slow playback speed.

[Effect]

If you reproduce the image signal recorded on one recording track by scanning it several times and calculate the sum of the same reproduced image signals, you will notice that noise due to tape fluctuations and thermal noise in the circuit system are added to random signals. Therefore, the increase in the amplitude value is small compared to the image signal.

Therefore, by dividing and averaging the added image signals, the S/N ratio is improved, and an improvement effect comparable to that of tape noise can be obtained.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the continuous image reproduction method of the present invention, 11 is a magnetic reproduction device for high-quality low-speed reproduction, and 12 is a reproduced image signal. A time axis correction device 13 detects signals of several frames before and after the recording track coincides with the scanning position of the playback head, as will be described later, and outputs a control signal for calculation. timing circuit, 1
Reference numeral 4 indicates an average image data calculation circuit including an A/D converter 14A, an addition circuit 14B, a frame memory 14C9, a division circuit 14D, and the like.

Note that 15 indicates a signal processing circuit for performing gamma correction on the film recording device 16 and controlling time axis expansion of image data, output timing, etc.

The still image continuous reproduction method of the present invention, which is embodied in the block diagram as described in Section 2, operates as shown below.

A magnetic reproducing device (VTR) is equipped with a mechanism that can reproduce a magnetic tape recorded at a steady speed at a low speed, for example, 1/8 times the tape speed. The recording track angle is set to match the scanning angle of the head by controlling the tape feed.

Therefore, as shown in Fig. 2, the image signal when reproduced by the head H which is on the rack for the recording track T is of the highest quality, but when played back at low speed, Since the tape speed has decreased, the image signal obtained by head H-1 that scanned l frame time ago and the image signal obtained by head H+1 that scanned l frame time later are only 1 rack. There is almost no signal deterioration compared to the image signal scanned by .

Therefore, in the present invention, when obtaining a single still picture using the timing circuit 13, for example, in the case of 1/8x speed, -
Control is performed so that the image signals at the positions of head H+)l-1 and H41 are taken into the arithmetic circuit 14 via the TBC 12.

That is, first, the image signal of track T in head n-+ is converted into image data by A/D converter 14A, and recorded in frame memory 14c via adder circuit 14B. Then, when the image data corresponding to the next helad H is input to the adder circuit 14B, the previous image data stored in the frame memory 14c is read out,
After the data corresponding to the image positions are added together, the image data in the frame memory 14c is rewritten. moreover,
When the image data of the head H41 is input, the second addition image data added to the similarly rewritten image data from the frame memory 14C is added to the frame memory 14.
control so that it is written to c.

When the addition of the image data described above is completed, the data in the frame memory 14c is loaded into the division circuit 14D by the control signal output from the timing circuit 13, and the same image data is divided by, for example, 1/3 calculation. Average data is calculated and output to the signal processing circuit 15.

FIG. 3 shows the timing of the signal waveform that performs such control. CTLS is a signal generated by a PLL circuit or the like in synchronization with the CTL signal indicating the recording track position, and is a signal indicating the track position CI +C2, C3. 8
The dividing timing pulse P6 corresponds to the track position MC1°c2. of the CTLS signal. The gate pulse detects the signals before and after c3, and for example, about 3 signals are extracted when the frequency is divided by 1/8, and about 5 when the frequency is divided by 1/16. When the frame pulse Pc extracted by this gate pulse PG is input to the arithmetic circuit 14, the write clock signal of the frame memory 14C,
A read clock signal and an addition clock signal are formed.

Pa indicates a calculation pulse supplied to the division circuit 14D,
The image data read out from the frame memory by this calculation pulse is sequentially subjected to 1/3 calculation and then supplied to the signal processing circuit 15.

In the above embodiment, processing of a still 11-two-picture signal obtained at 1/8x speed has been described, but it can be processed at 16x speed.

For 1730x speed, a still image signal with a better S/N ratio can be obtained using similar means. In this case, the amount of good image information obtained from one recording track can be further increased, and the S/N ratio improvement effect is further increased.

In addition to the above-mentioned embodiment, the calculation circuit that calculates the average image data from several frames of the same image data employs a digital circuit that calculates the average value while detecting the difference between the image data of each frame. You can also.

It goes without saying that the present invention can also be used in devices other than film recording devices that require low-speed image signals.

〔Effect of the invention〕

As explained above, the still image continuous playback method of the present invention extracts multiple frames of the same image signal obtained in low-speed playback mode, and performs averaging to reduce noise components from these image information. By, C/N
This has the effect of reducing deterioration of signals on magnetic tapes with low levels of noise. In particular, the present invention has the advantage of being able to record clear images when recording film using a slow speed playback device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the continuous still +1-image reproduction method of the present invention, FIG. 2 is an explanatory diagram of the reproduction position in low-speed reproduction mode, and FIG. FIG. 4 is a waveform diagram, FIG. 4 is an explanatory diagram of track angles, and FIG. 5 is a reproduction block diagram of a tape recorder showing the prior art. In the figure, 11 indicates a VTR 212, TBC 113 indicates a timing circuit, 14 indicates an arithmetic circuit, 15 indicates a signal processing circuit, and 16 indicates a film recording device. Timing fluid '84/Z Fig. 3 At4 time-of-life track and neck angle Fig. 4 Block diagram showing the special utsukai-uchi of A-1 retachi No. 1 Ebisu Fig. 5

Claims (1)

[Claims] In a magnetic recording/reproducing device configured such that the scanning angle of the magnetic head and the recording track angle match when the tape is run at a tape speed that is one-Nth of the recording tape speed, the magnetic recording/reproducing device is used for low-speed playback. A memory means capable of storing one frame of a desired image signal outputted when the mode is set as digital image data is provided, and the memory means stores n (n<N) frames of digital image data before and after the just track. A still image continuous reproduction method characterized in that digital image data consisting of an average value is formed and this digital image data can be output at a cycle of 1/N.