JPS61172493A - Still picture transmitting device - Google Patents

Abstract

PURPOSE:To monitor at the transmitting side how many binary actions are executed by providing the memory which accumulates binary picture data. CONSTITUTION:In a video signal inputted from a television video signal input terminal 101, through an A/D converter 1, the picture for one screen is accumulated to a picture line memory 2 and successively read in accordance with the speed (low speed) of a transmitting rate. In case of the binary mode, binary mode switches S1 and S2 are turned on, the picture signal is made binary by the speed of a transmitting rate by a binary circuit 6, and outputted through a band compressor 3 and a parallel-serial converter 4 to a transmitting line by a line output terminal 102. A binary picture memory 7 writes the binary data at a low speed, reads the data at a high speed, the read binary data are converted to the binary television signal by a D/A converter 5. The binary picture is taken out from an output terminal 103 and monitored at the transmitting side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a still image transmission device capable of monitoring a binarized image of a television video signal on a transmitting side.

[Prior art]

In recent years, video conferencing has attracted attention and is being put into practical use.

In addition to video conferences that transmit moving images, video conferences that use still images using existing telephone lines are also beginning to be used. The materials transmitted in video conferences are more often held using materials such as documents or drawings than single people or three-dimensional objects.

Used for video conferencing using traditional telephone lines. This type of still image transmission device is constructed as shown in the block diagram of FIG. In this diagram, input terminal 1
01 is sampled and then stored in the one-image memory 2.

The video signal stored in the image memory 2 is read out according to the speed of the transmission line, and is applied to a band compressor 3 that compresses the band using means such as DPCM.

The output of the band compressor 3 is applied to a parallel-serial exchanger 4, where it is converted into a serial signal, and output from a line output terminal 102 to a transmission line. Furthermore, the video signal is read out from the one-image memory 2 according to the speed of the transmission line as described above, and also read out at the high speed of the television rate.
The signal is converted into a television video signal by the D/A converter 5. This converted television video signal output is taken out through the terminal 103, and by monitoring this signal, the transmitted image can be monitored.

The still image transmission device configured in this way has one screen (one
field) for approximately 50 seconds (transmission speed 9600 pb
s). However, many of the documents and drawings mentioned above have black images on a white background, and in order to increase the transmission speed of one screen, a method of binarizing them may be considered. This binarization allows one screen to be transmitted in about 15 seconds. moreover.

By band-compressing this signal (run-length encoding, etc.), it is possible to transmit it at a high speed of about 5 seconds per screen.

By the way, the input television signal has uneven shading in the background of the original picture and uneven sensitivity of the camera.

Since there are various factors that cause the video signal to fluctuate due to uneven lighting, etc., it is necessary to monitor how much binarization has been performed on the transmitting side to know the extent of the binarization.

Therefore, if the binarization circuit is inserted between the image memory 2 and the band compressor 3 in Fig. 2, the binarization circuit only needs to operate at the transmission rate, so an LSI such as a signal processor can be used. can do. However, 2
Since the output of the digitizing circuit cannot be directly applied to the converter 5, it is not possible to confirm how much binarization has been performed.

Another method is to store a binarized image in the image memory 2 by inserting a binarization circuit between the v'D converter 1 and the image memory 2.

Binarized images can be monitored. but.

In this case, the binarization circuit must be operated at a high speed of television rate, which has the drawback of increasing the size of the hardware and increasing power consumption.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention was to eliminate the above-mentioned drawbacks of the conventional technology.
By writing the value signal into this buffer memory, reading it out at high speed of TV rate, and outputting the binarized television video signal through the D/A converter, the binarized image can also be monitored on the transmitting side. The object of the present invention is to provide a still image transmission device that can transmit images.

[Structure of the invention]

A still image transmission device according to the present invention includes means for digitizing an input television video signal, a memory for storing the digitized signal, and reading the digitized signal from the memory according to the speed of a transmission line. means and
means for binarizing the read signal, means for band compression of the binarized signal, means for sending the band compressed signal to a transmission line, and the binarized signal. The present invention is characterized by comprising: a buffer memory for accumulating , a means for reading a binary signal from the buffer memory at television speed, and a means for converting the read binary signal into a television video signal. do.

[Embodiments of the invention]

Next, two embodiments of a still image transmission apparatus according to the present invention will be described with reference to one drawing.

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention. In this example, a television video signal input terminal 101. 1. ψ converter that samples the input video signal and converts it into a digital signal; 1. Image memory that stores images for 1 screen (1 field or 1 frame); 2.
A band compressor that performs band compression3. Parallel-to-serial converter for converting parallel signals into series4. D/A converter that converts digital signals to analog signals5. A binarization circuit 6 that converts a digitized image signal into a binary signal, a binary image memory 7 that stores the binarized image signal, a line output terminal 102 to a transmission line. Television video signal output terminal 1
03 and binarization mode switches SL and S2 for controlling whether or not to use the binarization mode.

To explain the operation of this embodiment, the video signal input through the television video signal input terminal 101 is
After being sampled by the converter 1, it is supplied to the two-image memory 2, and in response to a writing instruction, one screen worth of images is stored therein.

Images and signals stored in the image memory 2 are sequentially read out according to the transmission rate (low speed).

The switches S1 and S2 are controlled so that the binarization mode is not selected. Therefore, among the image signals in the 1-image memory 2, the output read out at the TV rate speed (high speed) passes through the binarization mode switch S2,
After being converted into an analog signal by the /A converter 5, the television video signal output terminal 1 is output as a television video signal.
Output from 03. On the other hand, the low-speed image signal read from the image memory 2 and passed through the binarization yard switch S1 is subjected to band compression such as DPCM by the band compressor 3, and converted into a serial signal by the parallel-to-serial converter 4. After that,
The signal is output from the line output terminal 102 to the transmission line.

In the case of the binarization mode, the binarization mode switches S1 and S2 are turned "ON", and the image signal is binarized by the binarization circuit 6 at the transmission rate, and then passes through the switch S1 to the band compressor. 3 and is also added to the binary image memory 7.

The binary image memory 7 operates to write binary data at a low speed and to read it at a high speed. The read high-speed binary data passes through switch S2 to D/
The signal is added to the A converter 5 and converted into a binary television signal. By taking out this binarized image from the output terminal 103, it can be monitored on the transmitting side. Also,
The low-speed binary data applied to the band compressor 3 is subjected to band compression such as run length, and then passed to the parallel-to-serial converter 4.
After being converted into a serial signal, the line output terminal 10
2 is output to the transmission line.

According to the above embodiment, since the binarization circuit only needs to operate at the speed of the transmission rate, it is possible to use an LSI such as a signal processor, which has been greatly developed in recent years. In addition, since the input data of the binary image memory 7 is 1 pit/pixel, it is necessary to use a small capacity memory, for example, 256k×1
It can be easily configured with 1 bit IC chip.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, there are two
By adding memory to store digitized image data, it is possible to monitor how much binarization has been done on the sending side, and to set the screening level necessary for binarization. This has a great effect on improving maintenance and reliability in that it becomes easier to perform the process, and the same binary image can be viewed for both transmission and reception.

Margin below

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention;
FIG. 2 is a block diagram showing an example of the configuration of a conventional still image transmission device. In the figure, 1 is a ψ converter, and 2 is an image memory. 3 is a band compressor, 4 is a parallel-to-serial converter, 5 is a D/A converter, 6 is a binarization circuit, and 7 is a binary image memory.

Claims (1)

[Claims] 1. means for digitizing an input television video signal; a memory for storing the digitized signal; a means for reading out the digitized signal from the memory according to the speed of a transmission line; means for binarizing the binarized signal; and means for band compressing the binarized signal;
means for sending the band-compressed signal to a transmission line;
A buffer memory for storing the binarized signal, a means for reading the binarized signal from the buffer memory at television speed, and a means for converting the read binary signal into a television video signal. A still image transmission device comprising: