JPS6314586A - Television transmission system - Google Patents

Abstract

PURPOSE:To improve a vertical resolution and to correct the rapid movement of a picture by detecting the difference between a taken scanning line signal and the signal of a scanning line which succeeds thereto and is not taken out, multiplexing the detected line signal on a video signal in the occupied band of a transmission system and transmitting. CONSTITUTION:In a transmission side 1, the video signal of a standard system picked up by a TV camera 10 is scanned at a horizontal scanning speed twice an interlace system and fed via a delay circuit 13, a D/A conversion circuit 14 to a receiving side 3 through the transmission system 2. A digital signal from an A/D conversion circuit 11 is delayed by 1H by the interlace system having half a horizontal scanning speed, thereafter, fed to a subtraction circuit 16, this signal is subtracted from a signal which is not delayed and the obtained line difference signal is read in H frequency through a line memory 17. In the receiving side 3, the line difference signal is added to the even number the signal of the video signals in an odd number field by an addition circuit 34 and the line difference signal is added to the odd number the signal of the video signal in an even number field and original video signals are respectively restored.

Description

Detailed Description of the Invention (a) Industrial Application Field This invention is fully compatible with current standard television (hereinafter referred to as TV) systems such as NTSC, PAL, and SECAM, and is compatible with conventional television receivers. According to J, a new TV transmission method that can display images with the same quality as before, but with this type of receiver, it is possible to display images with significantly improved vertical resolution.Currently, standard TV NTSC, PAL, SECAM, etc. are often used as transmission systems, and all of these employ an interlace system. That is, NTSC
In this case, the number of scanning lines is 525, the number of frames is 30 frames per second, and PAL
, SECAM has 625 scanning lines and 2 frames per second.
There are 5 images, each of which consists of 1 frame image of 2 fields using an interlaced scanning method.

By the way, the reason why the interlace method is adopted in this way is to eliminate the flicker phenomenon on the receiver side without expanding the transmission band. In other words, an image of 1 frame is composed of 2 fields using the interlace method, and the image is
By setting the number of fields to 0 to 50, it is possible to obtain the necessary number of fields per second so that the flicker phenomenon does not become a problem without expanding the transmission band. However, by adopting the interlace method, the number of scanning lines in the l field is halved, so it is becoming more and more aware that the degradation in vertical resolution is surprisingly large (the Kell coefficient with the interlace method is 0.6). .

Therefore, as memory ICs have become more popular and cheaper,
The receiver has a built-in image memory, and the video signal sent in the interlaced format is temporarily stored in this image memory, and this memory is read out in the non-interlaced format at twice the horizontal scanning frequency (for example, NTSC: 31.5KHz). , twice the number of frames per second (e.g. 6 in NTSC)
Techniques for improving image quality by improving vertical resolution by displaying images in a non-interlaced manner at a rate of 0 frames per second (1 frame per second) are being researched and are beginning to be put into practical use.

An outline of this is shown in Figure 5. Here, the NTSC system will be explained as an example. On the transmitting side, an interlaced TV camera 51 takes a picture and sends the video signal to a wireless or wired transmission system 52 in an interlaced format. In other words, the number of scanning lines is 52
Five interlaced video signals of 60 fields/30 frames per second are sent. On the receiving side, the standard method is to receive the transmitted video signal with an interlaced receiver 53 and display it on a TV cathode ray tube in an interlaced manner with 525 scanning lines and 60 fields/30 frames per second. Therefore, a frame memory 55 is built into the non-interlaced receiver 54, and the video signal sent in the standard format is temporarily stored in the frame memory 55.
Store in. In this case, since the video signal sent is of an interlaced format, one frame of image is completed with two fields. After one frame of image is completed, the contents of this frame memory 55 are read out in a non-interlaced manner at 60 frames per second. Writing and reading of this frame memory 55 is controlled by a control circuit 56.

Then, on the non-interlaced receiver 54, the image is displayed in a non-interlaced format with 525 scanning lines and 60 frames per second, so the number of scanning lines per field is doubled, the vertical resolution is improved, and the image quality is improved. will improve.

Furthermore, since the display is performed at 60 frames per second, there is no problem with flickering.

It is true that such a method can significantly improve the image quality of still images. However, this is inconvenient for images of moving objects. For example, as shown in FIG. 6, assume that the path moves from left to right on the screen.

If the image in the odd field is as shown in Figure 6A, then in the immediately following even field there is a time difference of 1760 seconds, so the bus moves a little to the right, and the image in this field is as shown in Figure 6. It will look like B. Therefore, if the contents of the odd field (A) and even field (B) in the same frame are written to the frame memory to complete an image of one frame, and this is displayed as is in a non-interlaced format, as shown in Figure 6. This results in an unnatural double image as shown in C. In order to eliminate this unnaturalness, some attempts have been made to perform vector detection of the movement of a moving object and perform correction, but it is extremely difficult to correct scenes with complex movements.

(c) Purpose This invention does not constitute one frame with two fields, but transmits and receives signals of all scanning lines for each field, and images of all scanning lines of each field with a time difference are transmitted in a non-interlaced manner. Provides a new TV transmission system that improves the vertical resolution of the display, eliminates the problems associated with conventional images of moving objects, and is fully compatible with standard TV transmission systems that adopt the interlaced system. The purpose is to

(D) Summary of the Invention In the TV transmission system of the present invention, the imaging camera on the transmitting side sequentially scans at twice the normal horizontal scanning speed, for example, at 60 fields per second, and scans all 525 trees per field. Obtaining a non-interlaced video signal with twice the resolution in the vertical direction consisting of lines The scanning speed of the extracted scanning line signal is kept as usual.

By performing such conversion of the video signal, for example, at 60 fields per second, 525/1 field is converted.
A signal similar to an interlaced video signal in which one frame image of 525 trees is displayed 30 times per second in two fields is obtained, and this signal is sent via a transmission system.

On the other hand, the difference between every other signal that was not extracted and the extracted signal is detected. This line difference signal has a fairly high correlation between adjacent scanning lines, so
The amount of information is minimal. Therefore, it becomes possible to multiplex this line difference signal within the occupied band of the video signal and transmit it.

Therefore, on the receiving side, if a normal receiver does not have the function of receiving multiplexed interline difference signals, it will simply receive the same video signal as the normal interlace method described above, and then On the other hand, if a line difference signal is received and this line difference signal is combined with an interlaced video signal, the original 60 fields per second and 525 fields per second can be displayed. Since it is possible to restore a non-interlaced video signal with twice the resolution in the vertical direction consisting of all the scanning lines of It becomes possible.

Therefore, full compatibility with conventional conventional standard methods is maintained. Moreover, even if the image shows fast movement, the original 60 fields/second video signal, in which the l field has all the scanning lines, is restored as it is, which is different from the conventional method in which one frame is made up of two fields. Problems such as double images and movement correction do not occur, and the burden on the receiving side is reduced.

Note that it is possible to transmit the line difference signal for all minute gradation differences over the entire screen, but due to visual characteristics and interpolation effects, it is necessary to transmit the line difference signal to be multiplexed as efficiently as possible. Therefore, it is preferable to select and transmit only important items according to the interpolation position and interpolation signal level.

In other words, human vision has high resolution in the center of the eye, but not so well in the periphery. However, by shifting the viewpoint and focusing on points that show interest, the necessary resolution can be obtained in those areas.

Also, if you look at the drawing method, you will first draw the composition roughly, and then you will not necessarily be able to draw it in detail over the entire surface, but only in a relatively small number of necessary areas. I have completed a certain picture.

On the other hand, since TV images are displayed by scanning a rectangular area in parallel, the resolution of the entire area to be expressed is the same. However, in general television receivers, the scanning amplitude is set large due to the desire to express large images, and the display range is 85 to 90 degrees in both the vertical and horizontal directions of the image transmission range A, as shown by the dotted line B in Figure 2. %, the actual situation is around 73-80%. Therefore, when creating actual TV images, consideration is given to concentrating important scenes on the transmission screen in the center of the screen. being done.

Therefore, the line difference signal is transmitted only within a more limited central range C within the display range B of the actual receiver, and interpolation is performed only within this range C to increase the resolution. However, in actual visual terms, a sufficient effect can be obtained.

In addition, generally, as the number of horizontal scanning lines on a screen increases, the correlation between adjacent scanning lines becomes extremely high.

Therefore, even if the line-to-line difference signal is limited to area healing (as shown in Figure 2 C), and only those with large signal levels are selected and transmitted, the effect of improving vertical resolution can still be obtained. It will be done.

Further, regarding the color signal component, interpolation is not necessary due to visual characteristics, and only the luminance component is sufficient.

(E) Embodiment This embodiment will be explained using the NTSC standard system as an example. In FIG. 1, a video signal is sent from a transmitting side 1 to a receiving side 3 via a transmission system 2.

On the transmitting side l, the NTSC fi quasi-system 2 debit scanning speed (
A TV camera 10 that sequentially scans in a non-interlace format at a frequency of 31.5 KHz), an analog-to-digital converter (A/D converter) 11, a line memory 12 for converting from a non-interlace format to an interlace format,
A delay circuit 13 for phase adjustment and a digital/analog converter (D/A converter) 14 are provided. Also, IH (
1 horizontal scanning period), a subtraction circuit 16, a line memory 17, and a simple frame memory 1.
8. The transmission system 2 equipped with the coding circuit 2819 includes wireless or wired transmission systems 21 and 22 via appropriate transmitting/receiving devices (not shown). In addition, as the transmission system 2, an offline transmission system such as a recording session playback system using a recording medium such as a video tape can also be considered.

On the receiving side 3, an A/D converter 31. line memory 32,
D/A converter 33. Adding circuit 34, decoding circuit 35. A frame memory 36, a D/A converter 37, and a progressive scanning color monitor device 38 are provided. moreover,
At the receiving end 3, a standard color receiver 39 is shown to demonstrate compatibility.

In the configuration shown in FIG. 1, the TV camera lO on the transmitting side lO
The frequency is 31.5KHz, which is twice the horizontal synchronization frequency of the normal (NTSC system), and the
By sequentially scanning 25 horizontal scanning lines in a non-interlaced manner, R, G, and B (red, green, and blue) non-interlaced video signals are output. In this way, one image consisting of 525 horizontal scanning lines is obtained every 1/60 second (1 field).

This video signal is converted into a digital signal by the A/D converter 11 and then temporarily written in the line memory 12. This line memory 12 has a storage capacity for at least two horizontal scanning lines, and the scanning line signals sequentially sent from the A/D converter 11 are sequentially written therein. Then, the read speed is set to half the write speed (31.5 KHz, which corresponds to the above-mentioned horizontal scanning speed), and reading is performed every other scanning line. In this way, in the first field (1/60 second), the signal of the odd-numbered scanning line of the video signal of the progressive scanning system is transmitted to the next field (1/60 second).
760 seconds), the signals of even-numbered scanning lines are
It will be output at a horizontal synchronization frequency of 15.75 KHz. For example, as shown in FIG. 3A and F, a non-interlace video signal (still image) is sent to the A/D converter 11.
If it is output every l/60 seconds from then, the first field (
1/60 seconds), and the video signal represented only by odd-numbered scanning lines as shown in B in the same figure is transferred to the second field (1/80 seconds).
In this way, a video signal represented by only even-numbered scanning lines as shown in G in the same figure is obtained, and in this way, 6
From a video signal of 0 fields/second and 60 frames/second,
60 fields/sec with 525 interlaced scans, 30
Conversion to a frame/second NTSC standard video signal is performed. This standard video signal is 1! After being converted back to an analog signal via the extension circuit 13 and the D/A converter 14,
It is sent to the receiving side 3 via the transmission system 21.

Therefore, the video signal sent via this transmission system 21 is a normal NTSC standard video signal itself, and is processed by a normal NTSC standard video receiver 39 at 60 fields/sec and 30 frames by 525 tree-interlaced scanning. Ichimu/
It can display NTSC standard images of seconds.

On the other hand, the digitized video signal output from the A/D converter 11 is delayed by IH in the delay circuit 15, and then sent to the subtraction circuit 16, where this signal is subtracted from the undelayed signal. A signal is obtained by subtracting the signal of a scanning line by the signal of the previous scanning line. This line difference signal is sent to a line memory 17 having a configuration similar to that of the line memory 12, and the line difference signal is read out every other scanning line at the horizontal synchronization frequency of the normal NTSC system. That is, in an odd field, the signal of an even numbered scanning line that has not been read out in the line memory 12 (FIG. 3C)
) is subtracted from the signal of the previous scanning line (the read signal of FIG. 3H) is subtracted from the signal of the previous scanning line (the read signal of FIG. 3G) to obtain an interlaced line difference signal (FIG. 3, I). In addition,
In this third diagram, I, the dotted hatching indicates a negative value. This interlaced line difference signal is sent to the transmission system 22 via the simple frame memory 18 and the coding circuit 19.

On the receiving side, first, the normal N received via the transmission system 21 is
TSC interlaced video signal (Figure 3 B, G)
After converting into a digital signal by the A/D converter 31,
It is temporarily stored in the line memory 32. And the normal 2
The signal of the same scanning line is read out twice at twice the speed (horizontal synchronization frequency 31.5 KHz). This allows 525 horizontal scanning lines to be sequentially scanned in a non-interlaced manner at 60 fields/second and 60 frames per second. A 77 second video signal is obtained. However, since the same scanning line is read out twice in this video signal, the received interlaced video signal (Fig. 3 B, G) is simply expanded twice in the vertical direction (Fig. 3 E, J), this video signal is D/A
The signal is sent to an adder circuit 34 via a converter 33.

On the other hand, the line difference signal received via the transmission system 22 passes through the decoding circuit 35 and is temporarily stored in a frame memory 36 for line difference signals, at a horizontal scanning frequency of 31.5 KH.
z is read out intermittently for each scanning line, and the D/A converter 37
The signal is sent to the adder circuit 34 via the .

Therefore, in the odd field, the adder circuit 34 adds the line difference signal shown in Figure 3 to the even numbered signal of the video signals shown in Figure 3E, and restores the original video signal as shown in Figure 3A. In the even field, the line difference signal in Figure 3 is added to the odd-numbered video signal as in Figure 3 J, and the original video signal as in Figure 3 F is restored. be done. That is, 60 fields/sec, 60
A frame/second video signal is restored and displayed on a color monitor 38, resulting in a high-definition image in the vertical direction.

Next, the transmission of the line difference signal will be explained in more detail.

Although all of the line difference signals may be sent, visual effects cannot necessarily be obtained even if this is done, so in this embodiment, the important ones are sent depending on the interpolation position and interpolation signal level. The transmission capacity of the transmission system 22 is reduced by selectively transmitting only those signals.

First, the line difference signal from the line memory 17 is stored in the simple frame memory 18, thereby limiting its storage. That is, in the TV transmission system, the range in which images can actually be sent is the period excluding vertical blanking and horizontal blanking, so it is the range shown by A in FIG. 2.

In this range A, the number of scanning lines is 482 per frame, 241 per field, and in the horizontal direction, the sampling frequency is 720 per scanning line at a sampling frequency of 13.5 MHz. Since an actual television receiver is configured to enlarge and display only the central portion as described above, the display range of a standard television receiver is as shown in FIG. 2B. Therefore, we decided to display only the central part of this actual display range B in high definition, and this high-definition display range was
Define as shown in Figure C. This range C can be set to, for example, approximately 70% of the center of the image transmission range A both vertically and horizontally, with 170 scanning lines per 1 field and 512 sampling points per 1 scanning line. Assuming that the line difference signal is only a luminance signal and its level is represented by, for example, 4 bits including positive and negative signs, the simple frame memory 18 has an address space of 170 vertical by 512 horizontal (total 87040). However, each depth can be 4 bits. Of the 87,040 line difference signals (L field dust) stored in this simple frame memory 18, for example, 110
Extract only 0 pieces and use the coding circuit 19 to
Each address and level are coded. The line difference signals limited to 1,100 per field in this manner are hereinafter referred to as limited line difference signals.

Various coding methods can be considered for efficiently compressing this limited line difference signal and multiplexing it into a video signal, but here we decided to divide it into blocks of 50 and transmit them as 24 blocks per l field. . However, each field contains 100 invalid data. For vertical address coding, the first scanning line of the transmission range (170 lines per field) is set to the O address, and an 8-bit absolute address is displayed for each block.
This was done by representing each bit using a 2-bit addition method. The horizontal address coding is based on the transmission range (second
The left end of Figure C) was set as 0 address, and each time the vertical address changed, it was added sequentially from 0 and displayed as 7 bits (0-127). Furthermore, one bit is added as a parity pit for every five line difference signals, and if an error is detected, the data in that block is invalidated thereafter. In this case, the bit rate is [((2+7+4)X 50+(8-2)÷I(lX2
4] /1 field = 959.04Kbits/5
ec k becomes.

The multiplexing of this data transmission of about 1 Mbits/see into the transmission of a TV broadcast video signal will be described next. In TV broadcasting in Japan, the occupied band of the broadcast signal is 6 MHz, as shown in FIG. 4A. Regarding the video signal, the lower sideband of the video carrier wave fv is 1.25 MHz as shown in A in the same figure.
, the upper sideband is limited to 4.2 MHz. Color subcarrier is 3.58MHz, audio carrier fa is +4.5MHz
It is in the z position. On the other hand, general video receivers have detection characteristics as shown in Figure 4B, and the overall video signal characteristics are flat from 0 to around 4MHz, as shown in Figure 4C. It has become. From these figures A and B in Figure 4, the lower sideband of the video carrier fv is necessary to maintain the characteristics after detection;
It can be seen that frequencies up to 5 MHz are hardly used.

Therefore, as an example, as shown in FIG. 4E, the video carrier f
New FM at frequency fe of -0,75MHz for v
We set up a carrier and measured the interference to current normal receivers through experiments.

As a result, when interleaving is not performed, interference can be detected at about -40 db compared to the video carrier wave, but when interleaving is performed, interference can be detected at -40 db compared to the video carrier wave.
Data was obtained showing that no interference occurs up to level b.

In the future, if the filter characteristics of general television receivers are improved and become steeper from the dotted line to the solid line shown in Figure 4,
It is expected that interference will be further reduced.

Based on these results, in this embodiment, as an FM carrier for inter-noping, fe=((2n+1
)/2) fh f h ; 15.734284 KHzn=-48 Therefore.

Set f e = −0,74737754MHz,
This carrier has the above bit rate of 959.04Kbi.
The video signal was multiplexed by modulating it at ts/sec. In this case, the limited line difference signals described above can be multiplexed within the occupied band of TV broadcasting without causing any interference to general receivers.

Although the explanation was given using the NTSC standard system as an example, there are other PAL formats as well.
, SECAM, etc. is obviously applicable.

(f) Effects In the TV transmission system according to the present invention, the resolution in the vertical direction can be improved by performing non-interlaced display of all scanning lines for each field. Since the video signal of each field is originally a video signal captured within the time of that field, unlike the conventional case where video signals of two fields obtained at different times are combined, the video signal of a moving object is No problems with images. Moreover, it is completely compatible with the standard interlaced TV transmission system, and can be received by standard TV receivers without any problems.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing a scanning plane of a video signal, FIGS. 3 A to J are diagrams of video signals for explaining the operation, and FIG. -E is a frequency spectrum diagram, FIG. 5 is a block diagram of the conventional example, and FIG. 6 is a schematic diagram of a screen for explaining the problems of the conventional example. l...Transmission side 2,21.22...Transmission system 3...Reception side lO...Sequential scanning TV camera 11.31...A/D converter 12.17.32
... Line memory 13.15 ... Delay circuit 14
, 33.37...D/A converter 16...subtraction circuit
18... Simple frame memory 19... Coding circuit 34... Adding circuit 35... Decoding circuit 36... Frame memory 38... Sequential scanning color monitor device 39... NTSC system receiver 51...Interlace TV camera 52...Transmission system 53...Interlace receiver 54...Sequential scanning image reception 1t55...Frame memory 56...Control circuit

Claims (4)

[Claims] (1) In a television transmission system in which an interlaced video signal is transmitted from the transmitting side to the receiving side via a transmission system and the image is displayed on the receiving side, the transmitting side transmits the interlaced video signal to be transmitted. 2 of horizontal scanning speed
an imaging means that outputs a non-interlaced video signal by line-sequential scanning at twice the horizontal scanning speed; a video signal conversion means for obtaining an interlaced video signal by changing the horizontal scanning speed of the non-interlaced video signal; a transmitting means for sending out the interlaced video signal; a signal of the extracted scanning line; and a multiplex transmission means for multiplexing and transmitting the detected inter-line difference signal within the occupied band of the video signal transmission system. The receiving means includes a means for receiving an interlaced video signal, a means for receiving the multiplexed line difference signal, and a means for receiving the received interlaced video signal and the line difference signal. 1. A television transmission system comprising means for restoring a non-interlace video signal, and image display means for displaying the restored non-interlace video signal in a non-interlace format. (2) The television transmission system according to claim 1, wherein only significant line difference signals are selected and multiplexed. (3) The television transmission system according to claim 1 or 2, characterized in that the interlaced video signal transmission system is based on a standard system. (4) The video signal restoring means stores a line memory for at least one scanning line of the received interlaced video signal, and scans the line of the received interlaced video signal at twice the horizontal scanning speed of the received interlaced video signal. A patent claim characterized in that it comprises means for reading data from a memory twice in succession, and means for adding the received line difference signal to one of the signals of one scanning line that has been read out twice. range 1
Television transmission method described in section.