JPS61251282A - Still picture reproducing system - Google Patents

Abstract

PURPOSE:To prevent the generation of a blurring of a reproduced picture in a frame still reproduction and to prevent the deterioration of a vertical resolution in a field still reproduction by selecting the frame still reproduction and the field still reproduction in accordance with the difference of the information between successive two fields. CONSTITUTION:When reproducing a still picture, a level comparing means 7 for obtaining a level difference between a first signal obtained by demodulating a reproduced signal from a first rotating video head sliding and scanning on a magnetic tape together with a second rotating video head 3 for reproducing a field of plural rotating video heads 3a, 3b for a normal reproducing and a second signal obtained by demodulating the reproduced signal from the second rotating video head 3c is disposed. By this level comparing means 17, when the level difference is larger than a reference level, the reproduced signal by the field still reproduction having a blurring in the reproduced picture image is manually or automatically selected and outputted. When the level difference is smaller than the reference level, the reproduced signal by the frame still reproduction high in a vertical resolution is manually or automatically selected and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a still image reproduction system, and more particularly to a still image reproduction system in a helical scanning video tape recorder capable of field still reproduction and frame still reproduction.

″ Conventional technology Conventional helical scanning video tape recorder (VT
Still image reproduction methods in R) include frame still reproduction in which two consecutive fields are alternately reproduced, and field still reproduction in which only one field is repeatedly reproduced. Here, FIG. 2 shows a plan view of the rotary head drum. In the figure, a rotary head drum 1 is rotating together with a rotary shaft 2 in six directions of arrows. Further, rotating video heads 3a and 3b having different azimuth angles are attached to the rotating head drum 1, facing each other at 1800 degrees, and furthermore, special playback heads 3a and 3b having the same azimuth angle as the rotating video head 3a used during still playback are installed. A rotary video head 3C is mounted at a position substantially opposite to the rotary video head 3a.

In the above configuration, during recording, as shown in FIG. 3 or FIG. 4, the rotating video heads 3a and 3b alternately record images on video tracks 5a and 5b, etc. on the magnetic tape 4 running in the direction of arrow B. For example, the frequency change I
A video signal consisting of an I (FM) luminance signal and a low frequency conversion carrier color signal was recorded.

When the frame still reproduction is performed on the magnetic tape 4 on which the video signal has been recorded, the running of the magnetic tape 4 is stopped, but the rotary head drum 1 rotates, as shown in FIG.
Rotating video heads 3a and 3b each having a different azimuth angle
alternately scan the broken line portion 6 in the direction of arrow C. In this case, rotating video heads 3a and 3b reproduce half of video track 5a and half of video track 5b, respectively.

In this way, two consecutive fields, ie, one frame, are repeatedly reproduced.

On the other hand, in the case of field still playback, as shown in FIG.
C alternately scans the broken line portion 7 in the direction of arrow C. In this case, since both rotating video heads 3a and 3C reproduce only the video track 5a, one field is repeatedly reproduced.

Problems to be Solved by the Invention However, when an attempt is made to reproduce a fast-moving image using the frame still reproduction described above, there is a large difference in the information contained in the video signals of the two fields to be reproduced, so that the reproduced image becomes This will cause blurring. Furthermore, although field still reproduction does not cause blurring in the reproduced image as described above, it generally has problems such as lower vertical resolution compared to frame still reproduction.

Therefore, an object of the present invention is to provide a still image reproduction method that solves the above problems by selecting frame still reproduction or field still reproduction according to the difference in information between two consecutive fields. do.

Means for Solving the Problems In the still image playback method of the present invention, when playing still images, a second rotating video head for field playback among a plurality of rotating video heads for normal playback is simultaneously moved onto a magnetic tape. Obtaining the level difference between a first signal obtained by demodulating a playback signal from a rotating video head that performs dynamic scanning and a second signal obtained by demodulating a playback signal from a second rotating video head. It consists of level comparison means.

Operation: When the level difference is larger than the reference level, the level comparison means manually or automatically selects and outputs a playback signal from field still playback in which the playback image is not blurred;
When the level difference is smaller than the reference level, a reproduced signal by frame still reproduction with high vertical resolution is selected and output manually or automatically.

Embodiment FIG. 1 shows a block system diagram of an embodiment of the still image reproduction system according to the present invention. In the figure, the same components as in FIG. 2 are given the same reference numerals. Here, rotating video head 3
The first video signal q of one frame which is still reproduced by a and 3b is supplied to a color signal reproduction system 9 and a luminance signal reproduction system 10 via a delay element 8, respectively. On the other hand, the second video signal of the one field still reproduced by the rotating video head 3C is supplied to a color signal reproduction system 12 and a luminance signal reproduction system 13 via a delay element 11, respectively.

The color signal reproduction systems 9 and 12 are connected to the incoming first and second color signal reproduction systems 9 and 12.
For example, one wave of low-band converted carrier chrominance signals is generated from each of the video signals, and these are frequency-converted to become carrier chrominance signals of the original band. On the other hand, the luminance signal reproducing systems 10 and 13
A frequency modulated luminance signal is generated from each of the second video signal and the second video signal, and these are subjected to FMl[II to obtain a luminance signal.

The reproduced carrier color signal and the reproduced luminance signal taken out from the color signal reproduction system 9 and the luminance signal reproduction system 10, respectively, are sent to an adder 1.
4 and is added to form a first reproduced color video signal, which is then supplied to a switching circuit 15. Similarly, the reproduced carrier color signal and the reproduced luminance signal respectively taken out from the color signal reproduction system 12 and the luminance signal reproduction system 13 are supplied to the adder 16, where they are added to form a second reproduced color video signal. The signal is supplied to the switching circuit 15.

On the other hand, reproduced luminance signals extracted from the luminance signal reproduction systems 10 and 13 are supplied to a comparison circuit 17. here,
Both page raw signals from the rotating video heads 3b and 30 are time-aligned in advance by the delay elements 8 and 11 so that the comparison circuit 17 can compare the luminance information at the same position on the television screen. In this way, the comparison circuit 17 determines the level difference between the two reproduced luminance signals at the same position on the television screen, and compares it with a predetermined reference level set in advance. Here, for example, if the level difference of the reproduced luminance signal is larger than the reference level, the difference in information between the video signals of two consecutive fields recorded on two adjacent tracks is large, so the reproduced image will be The comparator circuit 17 outputs a second switching signal to the switching circuit 15 in order to select the second reproduced color video signal that has been reproduced as a field still without blur. On the contrary, if the level difference of the reproduced luminance signal is smaller than the reference level, the difference in information between the video signals of two consecutive fields is small, so the vertical resolution ^
The comparator circuit 17 outputs a first switching signal to the switching circuit 15 in order to select the first reproduced color video signal that has been reproduced as a frame still.

The switching circuit 15 switches the first or second reproduced color video signal according to the incoming first or second switching signal and selectively outputs the signal to the output terminal 18. The timing at which the first or second reproduced color video signal is switched by this switching signal is, for example, switched each time the level difference of the reproduced luminance signal exceeds the reference level, and the timing is changed each time a frame is partially displayed on the TV screen. Still playback and field still playback may be switched, and frame still playback and field still playback may be switched in the vertical blanking period after the time when the level difference of the reproduced luminance signal exceeds the reference level, that is, in units of one field. may be switched.

Note that the delay elements 8 and 11 may be connected in the order in which they are placed behind the color signal reproduction system 9 and the 12.1 degree signal reproduction threads 10 and 13, and as shown in FIG. When the head 3C is located rearward in the rotational direction than the rotating video head 3b, the delay element 11 may be omitted.
On the other hand, if the rotating video head 3C is located further forward in the rotational direction than the rotating video head 3b, the delay element 8 may be omitted. Furthermore, switching between the first and second reproduced color video signals by the switching circuit 15 may be performed manually.

As described above, two consecutive
Depending on the difference in information between fields, frame still playback and field still playback are switched to obtain still images of higher quality. Note that since there is not much difference in color signals between two consecutive fields, the color signal reproduction system 12 is omitted in the block diagram shown in FIG. The color signal may also be supplied to the adder 16.

Effects of the Invention As described above, according to the present invention, images with little movement can be reproduced as stills by selecting between frame-shift playback and field-still playback according to the difference in information between two consecutive fields. In this case, it is possible to obtain a still image with no deterioration in vertical resolution, and in the case of still reproducing an image with a lot of movement, it is possible to obtain a still image without blur in the reproduced image.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the still image reproduction method according to the present invention, Fig. 2 is a plan view of a rotating head drum, and Figs. 3 and 4 are frame still reproduction and field still reproduction, respectively. FIG. 3 is a tape format diagram showing an example of the operation of a rotating video head at a time. 1... Rotating head drum, 3a, 3b... Rotating video head, 3C... Rotating video head for special playback, 4
... Magnetic tape, 5a, 5b... Video track,
8.11... Delay element, 9,12... Color signal reproduction system, 10.13-... Luminance signal reproduction system, 14.16...
Adder, 15. 17... Switching circuit, 18... Playback video signal output terminal.

Claims (1)

[Claims] In a helical scanning video tape recorder having a plurality of first rotary video heads for normal playback and a second rotary video head for field still playback, one of the first rotary video heads during still image playback. A first signal obtained by demodulating the playback signal from one rotating video head that slides and scans on the magnetic tape at the same time as the second rotating video head, and demodulating the playback signal from the second rotating video head. and a level comparison means for obtaining a level difference with the second signal obtained by the second signal, and when the level difference is larger than the reference level, manually or automatically selects and outputs the reproduced signal from the field still reproduction. . A still image playback method, characterized in that when the level difference is smaller than the reference level, a playback signal from frame still playback is selectively output manually or automatically.