JP2790538B2 - Two-way simple video communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention

Regarding the two-way simple moving image communication control device, by thinning out the pixels of the moving image and by thinning out the screen to make it a small number of screens, it is possible to transmit and display not only still images but also moving images at the still image search / register terminal A bus, a still image memory connected to the bus, image capturing means for capturing an image signal obtained from the camera and writing the still image memory via the bus, and a communication line. After storing the received data in the reception buffer, the data is decompressed and written to the still image memory as image data, and the data from the image capturing unit written to the still image memory is compressed, and the compressed data is stored in the transmission buffer. After that, a communication control means for transmitting to the communication line is provided.

[Industrial applications]

The present invention relates to a two-way simple moving image communication system using a still image search / registration terminal. In recent years, with the spread of low-cost high-speed circuits such as ISDN, advances in LSI technology, and advances in high-efficiency image compression technology, the image information transmitted by communication lines is also required to be information of even higher utility. ing. At present, even more natural images, such as color photographs, can be displayed, transmitted, and processed on small, low-cost devices such as personal computers and workstations. However, the demand for transmission information is unaware of the end, and it is demanding a natural still image such as a photograph to further express the movement.

[Prior art]

There are the following differences between moving picture transmission and still picture transmission.
That is, in order to express a moving image as completely smooth motion, very high-speed image transmission and display of 30 frames / sec is required as in a television. However, since the moving image changes (rewrites) one after another, it is not necessary to express a very fine portion, and it is difficult to perceive even a rough surface. On the other hand, in the case of a still image, since one image tends to be watched for a long time, it is easy to notice the failure of a small portion and to lower the evaluation. However, since there is no temporal image change, the transmission and display time is less restricted than a moving image, and a relatively low speed may be used. As described above, since the characteristics of the image and the function of the transmission device are greatly different between the moving image and the still image, the respective dedicated devices have been conventionally used. Fig. 5 shows the outline. In FIG. 5, reference numeral 10 denotes a still image search / registration terminal,
(Audio Visual) An input acquisition unit 11, a communication control unit 12, a still image CODEC (Coder Decoder) unit 13, an image bus 14, a still image memory 15, and the like. 16 is a still image / moving image synthesizer, 17
Is a display, 18 is a moving image communication device, and 19 is an AV input device such as a television camera or a VTR. The moving image is received and displayed by a system of a communication line, a moving image communication device (including a CODEC) 18, a synthesizing unit 16, and a display 17, and is transmitted by a system of an AV input device 19, a moving image communication device 18, and a communication line. And the still image is a communication line, a communication control unit 12, a still image CODEC unit 13, a memory 1
5, received and displayed by the system of the synthesis unit 16 and the display 17,
AV input device 19, capture unit 11, memory 15, CODEC 13,
The control unit 12 is transmitted by a communication line system. As described above, in a terminal device that handles a moving image and a still image, both systems need to be provided in parallel, so that the size of the device is increased. In addition, since the transmission system for still images and the transmission system for moving images operate as completely different functions, when using moving images and still images in combination,
Processing and hardware for synthesizing both images are required, which results in an increase in the size of the apparatus and in complexity of the processing.

[Problems to be solved by the invention]

The still image search / registration terminal device basically includes one image bus, one still image memory, and one still image CODEC. Therefore, simultaneous processing of complex functions,
There are many restrictions in performing bidirectional communication of moving images that require simultaneous capture and display of complicated screens. The present invention improves such a point and realizes that a still image search / registration terminal can transmit and display not only a still image but also a moving image in a bidirectional manner by thinning out pixels of a moving image and thinning the screen to a small number of screens. It is the purpose.

[Means for Solving the Problems]

As shown in FIG. 1, in the present invention, only a still image transmission system is used, and a moving image is also handled. The moving image is reduced (decimated) to 1 / n, for example, 1/4 in both horizontal and vertical directions. SCLK is a clock for performing this 1 / n sampling. With this thinning, the data amount of one screen becomes 1/16. Then, when the transmission of one screen is completed, the next screen is transmitted, thereby reducing the number of transmission screens per unit time. Although the image bus 14 is one, taking in the external AV input and
At the time of data compression / expansion operation for transmission / reception, switching is performed by the image bus control unit 22 so that the image bus operates as a dedicated bus. The communication buffer 23 is provided with an area in which data for each screen for transmission and reception can be stored, thereby speeding up the processing in the terminal and coping with the use of bus switching.

[Action]

With this configuration, a moving image is treated in the same manner as a still image, and bidirectional reception and display of a still image and a moving image can be performed only with a still image system. That is, in the case of television broadcasting, the screen is 30 images / second,
In this case, even if the image quality is lowered (thin pixels in one screen are thinned out and the number of pixels is reduced), it is difficult to transmit using a high-speed communication line (about 64 Kbps) currently generally available. However, with 1/4 sampling, one screen is 1/4 both horizontally and vertically,
By making it 1/16 overall, the next screen is sent after one screen has been sent. By using the above communication line, about 10 sheets / second can be transmitted. It is possible. Also, the display 17 simultaneously displays the image sent from the communication partner and the image sent by the user, so that the still image memory
15 is also the same (your image and the other party's image are written), but if you perform normal capture at the time of still image registration, the full display area will be captured, so it was sent from the communication partner Crush the image. In addition, when the writing area to the still image memory is limited, a part of the image to be displayed on one screen is cut off. In this regard, in the present invention, 1 /
Since sampling is performed by thinning to 4, the image is 1 in both the vertical and horizontal directions
It is reduced to / 4 and does not crush the partner image.
The area for developing the partner image on the still image memory and the own image development area are separately determined in advance. Also, since it is necessary to limit the display area of the partner image and the self image, if the image is transmitted without being aware of this, it is necessary to edit (reduce) the image on the receiving side,
The number of processing processes increases and the time until display is delayed. In addition, since unnecessary image data that is discarded due to reduction is transmitted, uneconomical use of a communication line and loss of transmission time are caused. As in the present invention, by thinning out and sending only necessary data to the other party, the transmission efficiency is improved, and the other party only needs to write and display the received data at the expected position, reduce the processing amount and display Speedup is achieved. Currently, high-speed lines that can generally be used have a transmission speed of about 64 Kbps, and the amount of data that can be transmitted with this is still image CO
Much less data than DEC can handle. Therefore, if the data compression / decompression processing is sequentially performed in accordance with the transmission speed of the line, other operations cannot be performed because the image bus is occupied during that time, and the overall processing speed is reduced.
In this regard, if the communication buffer 23 is provided, the data is temporarily transmitted, the received data is stored in the buffer, and the compression / expansion processing is collectively performed for one screen at the maximum processing speed of the still image CODEC. It is possible to speed up the entire processing. Also, while receiving the data of the other party's image,
Acquisition from devices and compression operations can be performed in parallel.

【Example】

To further explain FIG. 1, the external AV input capturing unit 11
A still image to be registered is input from an external AV input device 19 and converted into digital data to be developed in the still image memory 15. The image bus control unit 22 manages a still image memory and an image bus, such as writing an input image to a still image memory, reading from a still image memory for registering a still image, and writing a search image to a still screen. Do. The still image memory 15 is also used as a memory for temporarily storing an input image and a search image, a memory serving as a source of a registered image, and a display memory. Further, the still image CODEC 13 expands the search image data and compresses the registered image data. The communication buffer 23 is used for searching /
This is a communication buffer for compressed image data to be communicated in the registration process. Further, the communication control unit 12 controls communication with the host of the compressed image data or the opposite still image search / registration terminal,
And line interface. The display control unit 21
Converts the image data developed in the still image memory 15 into a display display video signal. In addition, the image bus 14 transfers image data between each unit in the terminal. These are exactly the same as or slightly different from those of FIG. In the present invention, it is possible to transmit and display a moving image without significantly changing the configuration of the still image search / registration terminal shown in FIG. FIG. 2 shows the configuration of a still image search / registration terminal to which the present invention is applied. Image bus controller 22 is a still image memory for input video
Supports standard capture mode and quarter sampling capture mode when writing to 15. Further, it outputs a switching control signal BS for switching the image bus for each operation mode. Reference numeral 29 denotes a bus buffer amplifier, which switches between operation and non-operation according to the signal BS. The still image CODEC 13 decompresses the search image data, compresses the registered image data, compresses its own image, decompresses the partner image, and controls data read / write to / from the communication buffer. The communication buffer includes a reception buffer 23b and a transmission buffer 23a. The former is for storing the received compressed image data and has a capacity to store one screen. The latter is for storing compressed image data to be transmitted, and has a capacity to store one screen. The image bus 14 transfers image data between the units in the terminal. The image bus 14 is switched and controlled by a switching signal of the image bus control unit, and operates as a dedicated bus for each operation mode. The flow of the operation in the case where bidirectional simple moving image communication is performed by this device and a simple moving image screen is displayed as shown in FIG. 3 will be described below. In FIG. 3, 17a is a still image display area, and 17b is a simple moving image display area.
The item numbers in the following description correspond to the line numbers indicating the data flow in FIG. Capture of own image: A transmission video is input from the AV input device 19 via the external AV input capture unit 11, reduced by 1/4 sampling capture, and developed in the area of the still screen of the own screen. At this time, the image bus 14 is exclusively used for a function of capturing a video input. Fig. 4 shows the procedure for 1/4 sampling. (1) is a video input signal, (2) sampling by conventional sampling clock SCLK _1, (3)
Indicates the sampling by one-fourth the sampling clock SCLK _2. Data (sample) by sampling with SCLK ₁
... are obtained, one sample ... is obtained 5 samples at the sampling by the SCLK _2. This is thinning out in the horizontal (line) direction, but also in the vertical direction.
Thinning is performed by adopting only one line per line. Compression and transmission of own image: Only the area necessary for the communication partner to display is read out from area A of the own screen in the still image memory 15 and the still image CODEC 13 compresses the whole image. At this time, the image bus 14
, And is exclusively used for data transfer to the still image CODEC 13. The compressed data is accumulated in the transmission buffer 23a until the processing for one screen is completed. Therefore, the still image CODEC 13
Without being affected by the operation of other parts or the transmission speed of the line,
High-speed compression processing at the highest processing speed becomes possible. Also, during this period, since the line is not used, reception of the partner image can proceed in parallel. The transmission is started when the compressed data for one screen has entered the transmission buffer, and when the transmission is completed, the external AV input acquisition unit 11 starts the thinning of the next screen. With this method, the transmission screen becomes about 10 images / second (the communication line is 64 Kbps), and pseudo moving image transmission and display are possible. Waiting for reception of the data of the partner image; capturing the data of the partner image into the reception buffer 23b via the communication line and the communication control unit 12. This continues until one screen has been received. Decompression of the partner image and expansion to the still image memory; when the data of the partner image has been received for one screen, the reception buffer 23
The image of the other party is read from b, input to the still image CODEC 13, and the image is expanded for one screen at a time. Since the other party's image is transmitted only the part necessary for display, the decompressed data is
The data is written as it is in the area B designated in the still image memory as the partner image data. At this time, the image bus 14
It is exclusively used for data transfer from the DEC unit 13 to the still image memory 15. Therefore, the still picture CODEC can perform high-speed decompression processing at the maximum processing speed without being affected by the operation of other parts or the transmission speed of the line. Also, during this period, the line is not used for reception, so that the transmission of the own image can be performed in parallel. By continuously performing the above operations (1) to (5), both the self image and the partner image can be displayed as moving images.

【The invention's effect】

As described above, according to the present invention, without changing the basic configuration of the still image search / registration terminal device constituted by one image bus, one still image memory, and one still image CODEC, Image can be realized in two-way communication between terminals. The present invention greatly contributes as a basic technology for miniaturizing a still / moving image communication device such as a videophone device having a still image search function.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is an explanatory diagram of a screen display example, FIG. 4 is an explanatory diagram of sampling, and FIG. FIG. In FIG. 1, reference numeral 11 denotes an external AV input capturing unit, 12 denotes a communication control unit, and 13
Is a still image CODEC, 14 is an image bus, 15 is a still image memory, 1
7 is a display, 21 is a display control unit, 22 is an image bus control unit, and 23 is a communication buffer.

Continuation of front page (56) References JP-A-2-257778 (JP, A) JP-A-2-63288 (JP, A) JP-A-2-246486 (JP, A) JP-A-61-159883 (JP) , A) JP-A-63-234789 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 7/14

Claims (1)

(57) [Claims] 1. A still image memory for storing still image data including at least a transmission image area and a reception image area allocated in advance, and the transmission of the still image data stored in the still image memory. The transmitting side image stored in the image area is compressed and transmitted via the transmission line via the transmission buffer,
A communication control means for decompressing the received data once stored in the receiving buffer after receiving via the communication line and writing the data as a receiving-side image in the received image area of the still image memory. Further, while reducing the number of screens per unit time of the moving image signal obtained by the camera, thinning out pixels in the horizontal scanning direction and the vertical scanning direction to generate the transmission side image,
An image capturing unit for writing to the transmission image area of the still image memory asynchronously with the still image transmission system is provided, and the communication control unit transmits the transmission side image stored in the transmission image area. At this time, the transmission side image for one screen is collectively compressed, stored in the transmission buffer for each screen and transmitted, and the received reception side image is stored for one screen in the reception buffer. Characterized in that it has a function of performing control so as to collectively decompress and write in the received image area.