JPS5853825B2 - Image transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image transmission method for transmitting high resolution images in a lower frequency band.

Generally, to transmit and display images such as documents and drawings,
It is said that 1,000 to 1,500 high-resolution lines are required, but if you try to transmit this using the same method as normal television, you will need a band of 20MHz (4)L, 30MHz.

Conventionally, methods to solve this problem include narrowing the band by speed conversion and narrowing the band by dot interlacing, but the former method cannot faithfully reproduce the movement of the subject, and the latter method causes flickering. There was a drawback that there was.

The present invention provides an image transmission method that takes advantage of the fact that images of documents and drawings that require high resolution are often binary images, in order to eliminate the drawbacks of the conventional examples.

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, where 1 is a low resolution (hereinafter referred to as the first method) camera, 2 is a high resolution (hereinafter referred to as the first method) camera, and 2 is a high resolution (
3 is a sampling/binarization circuit, 4 is a high-efficiency (for example, run-length encoding) circuit,
5 is a multi-value conversion circuit, 6 is a switch for switching between the first and second methods, 7 is a transmission line for the first method, 8 is a switch for switching between the first and second methods, 9 is a multi-value-to-binary conversion circuit, 10 is a decoding circuit, 11 is a monitor for the first method, and 12 is a monitor for the second method.

Furthermore, since the first method may be exactly the same as the normal television method, the second method will be explained below.

First, in the second method, the vertical scanning signal of the first method is subjected to high frequency modulation, and the scanning of the first method shown in FIG. 2A is performed as a wobbling scan as shown in the opening of FIG.

Here, 13 is the pixel, 14°15 is the first . This is the scanning line of the second field, and the scanning beam is assumed to be sufficiently thin.

As a result, a signal with many high frequency components can be obtained from the output of the second system camera 2 in exactly the same format as the output of the first system camera 1.

Next, the signal is binarized by converting the predetermined comparison level signal determined for each pixel and the camera output signal to each pixel as shown in Figure 3A. By outputting a white "1" signal when the camera output signal is larger and a black "O" signal when it is smaller than the camera output signal, halftones can be expressed pseudo-by the area ratio of white and black. This allows you to avoid image quality deterioration due to binarization for photographs included in drawings, etc.

In addition, 16 in FIG. 3A is a unit block.

Since this binarized signal has many white parts like a facsimile signal, the bit rate can be reduced by run-length encoding or the like.

In this run-length encoding, once the bit rate is determined, the communication time varies depending on the subject, but the bit rate is determined so that one communication time does not exceed the maximum one frame time using the one frame memory for the first method. As a result, the bit rate can be reduced to a fraction of a fraction, so the resolution can be improved by about twice.

Moreover, since the transmission path γ is capable of transmitting analog signals, by combining multiple highly efficient binary signals into one multi-value signal, the resolution can be further increased by about 1.5 times. It will be done.

In addition, by adding a circuit to the camera and monitor of the second method to start and stop the wobbling, and a circuit to make the electron beam thicker in the first method and thinner in the second method to the monitor as necessary. , camera and monitor can also be shared in both systems.

As explained above, according to the present invention, for subjects that require high resolution, °C can achieve high resolution of about 3 diopters by binarizing the signal and further transmitting it as a multi-level signal. Furthermore, since the scanning period and synchronization method for the first and second methods are the same, cameras and monitors can be shared by simple switching, and the equipment for the first method can be used for signals from the second method as well. In addition, the interframe coding device for the first method allows for much higher efficiency, and since it is possible to display complete moving images, it is possible to explain drawings etc. by pointing them out with your finger. The present invention can provide an extremely useful image transmission method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figures are diagrams for explaining the first and second scanning methods, and FIG. 3 is a diagram for explaining the binarization method for pseudo halftones. 1...First method camera, 2...Second method camera, 3...Sampling/binarization circuit, 4...
...High efficiency circuit, 5...Multi-value circuit, 6
...... Selector switch, 7... First method transmission line, 8... Selector switch, 9...
Multi-level binary conversion circuit, 10...Decoding circuit, 11
...Monitor for the first method, 12...2nd
Method monitor.

Claims (1)

[Claims] 1. In a television system that transmits low-resolution images and high-resolution images over the same analog transmission path, the horizontal and vertical scanning periods and synchronization signal system are the same for the low-resolution system and the high-resolution system, and the high-resolution system uses a predetermined A wobbling scan is performed, and the video signal obtained from the camera is sampled and binarized, a predetermined efficiency is increased, and a plurality of the binary signals are combined into a plurality of binarized signals to transmit the image signal of the low resolution method. A multi-level signal with a repetition frequency that can be transmitted in a frequency band sufficient for the above-mentioned signal is transmitted as a signal in the same format as the composite video signal of the low resolution method, and on the receiving side, a binary signal is obtained by inverse conversion and displayed. An image transmission method characterized in that: