JPH0638657B2 - Narrowband video communication system and device - Google Patents

Description

The present invention relates to a narrow band moving image communication system and apparatus, and more particularly to a communication system and apparatus for transmitting a moving image using a narrow band transmission path. Is.

(2) Description of Related Art A television communication device has been used as a conventional moving image communication device. As shown in FIG. 1, a television communication device uses a television camera 1 as a moving image input device, and an encoder 2 for spatial redundancy compression and temporal redundancy compression for a moving image obtained by this. The data is encoded by the above, transmitted to a distant place through the transmission line 3, the original moving image is restored by the decoder 4, and output / displayed to the television receiver 5. In this television communication device, the precondition for the image quality of the moving image to be transmitted is determined so as to have the screen configuration shown in FIG. That is, as an effective screen that can be visually recognized by humans, about 200 scanning lines are displayed in an interlaced display at a vertical resolution of 60 Hz, and a horizontal scanning signal bandwidth (about 3 MHz) and a color receiver are displayed as a horizontal resolution. The resolution is about 200 to 300 dots because it is limited by the pitch (0.7 to 0.4 mm) of the shadow mask and the beam spot size. Regarding the vertical resolution, about 400 scanning lines are displayed in terms of frame. In the following description, the vertical resolution will be represented by a frame representation. Such vertical and horizontal directions are about 400 x 200 to about 40
0x300 pixels with a physical size of 10 to 20 inches C
The moving image communication device is configured so that the display on the RT is a prerequisite. The size of the display screen corresponds to the length of the diagonal line of the effective screen in FIG. 2, and since the aspect ratio of the effective screen is 3: 4, a screen size of 10 to 20 inches has a screen area of about 310 cm. Equivalent to ² to about 1239 cm ² . Since there is such a precondition for the image quality, the amount of information I transmitted from the moving image input side to the output side I
Is given by the following equation, where H is the horizontal resolution.

In Formula (1), Table 1 shows an example of calculation when H = 200 to 300. Each image without compression of information When the information amount of 8 bits is given to the prime (N · C = 8), the transmission capacity is about 19.2 Mb / s to about 28.8 Mb / s.
Although s is required, information compression of N · C = 2 to 0.5 can be performed by using a compression method such as block coding or interframe differential coding that has already been devised.
A moving image can be transmitted with a transmission capacity of about 7.2 Mb / s to 1.2 Mb / s. However, it is extremely difficult to perform more information compression because satisfaction with the image quality is reduced, and thus it is difficult to transmit a moving image through a narrow band transmission path of about 100 Kb / s. there were.

(3) Object of the invention In order to solve these drawbacks, the present invention provides a display device which can maintain satisfaction with image quality.
It is an object of the present invention to provide a communication device capable of transmitting a moving image on a narrow band transmission line of about 0 Kb / s, and the drawings will be described in detail below.

(4) Description of Configuration and Action of the Invention First, the display device will be described. In a television communication device, the resolution of one screen is about 400 × 200 to about 4
Since it conveys a large amount of information of 00x300,
A large capacity transmission line of 1.2 Mb / s or more was required for moving image transmission. However, about 400 x 200 to about 400 x 300
The resolution is essential for the purpose of displaying complicated natural images such as TV movie displays and landscapes, but as auxiliary information of the conversation by communication when using a telephone etc., the face, facial expression, For the purpose of transmitting motions and the like as a moving image, it is sufficient to be able to distinguish an individual's face, facial expressions, and motions, which can be visually recognized with a resolution of less than one digit. On the other hand, in the conventional television communication device, it is premised that an image is displayed on a large CRT having a physical size of 10 to 20 inches, and when the image is displayed with a smaller resolution, the roughness of the pixels on the screen is conspicuous. For this reason, there is a problem in that the psychological satisfaction of the clarity of the image is extremely lowered, and the resolution cannot be reduced.

In the present invention, regarding the psychological measure for the clarity of the image,
When the number of pixels (resolution) in the screen is the same, paying attention to the psychological characteristic that the clarity of the screen is better when the physical size of the screen is smaller, and the resolution ( By reducing the number of pixels) to 1/10 and the screen size to 1/10 ² , it was possible to maintain psychological satisfaction with the clarity of the image. FIG. 3 shows a comparison between the conventional television communication device and the present invention regarding psychological clarity. FIG. 3 shows the result of an image quality evaluation experiment using a face image on the shoulder. The evaluation uses a five-level evaluation value generally called a MOS average opinion. In the figure, "very clear" is M
The OS score is an area corresponding to 5, where "clearness is normal" has a MOS score of 3, and "very bad clarity" is a MOS.
This is an area corresponding to a score of 1. Screen size: 10 ³ cm ² , number of pixels in screen: 1
0 ⁵ with a dot of television communication equipment. The graph of FIG. 3 uses a logarithmic scale on the vertical axis and the horizontal axis.

When compared with the target image of conventional television, the resolution is 1 /
When it is lowered to 10, do not reduce the screen size, or 1 /
If it is reduced to 10 (that is, reduction with the pixel density kept constant), satisfaction with the clarity cannot be maintained. It can be seen that in order to maintain satisfaction, it is necessary to reduce the pixel size to 1/10 ² and increase the physical pixel density. For example, the number of pixels is 1
0 ⁴ dots, the screen size 10 cm ^2, can be maintained satisfaction with image quality by increasing the pixel density to 10 times that of the conventional television.

By reducing the image resolution (number of pixels) to 1/10, the transmission speed required for moving image transmission can be reduced to 1/10 as compared with the conventional television communication device. Therefore, Table 1
At N · C = 0.5, 120 Kb / s-18
The transmission capacity is 0 Kb / s, and moving image transmission in a narrow band of 200 Kb / s or less can be realized.

FIG. 4 is a block diagram of an embodiment showing the basic concept of the present invention. In the figure, 6 is a moving image input unit, 7 is an input side frame memory, 8 is an information compressor, 9 is a transmission line, 10 is a decoder, 11 is an output side frame memory, and 12 is a display unit.

To operate this, the moving image captured from the moving image input unit 6 is temporarily stored in the frame memory 7. At this time, since the information for the number of pixels of about 10 ⁴ may be input / stored in the frame memory, CCD, MOS,
It can be realized by using a small solid sensor such as. Then, information of each frame is compressed by a compressor 8 such as block encoding or inter-frame differential encoding, transmitted through a transmission line 9, decoded by a decoder 10, and then temporarily stored in a frame memory 11 on the output side. The information is accumulated and the information is output to the display unit 12. At this time, since it is sufficient to display the number of pixels of about 10 ⁴ as the display unit, a small display such as a liquid crystal panel or a beam index type small CRT can be used.

FIG. 5 shows an embodiment of the present invention, in which 13 is a solid-state moving image input unit, 14 is a solid-state moving image display unit, and 1 is a solid-state moving image display unit.
Reference numeral 5 is a voice output unit, 16 is a voice input unit, and 17 is a transmission path. In the case shown in the figure, the above-mentioned moving image and sound input / output unit is solidified and integrated into a handy type housing, and a moving image of about 10 ⁴ size is handled and the screen size is approximately By making it 10 cm ² , it is possible to realize a small size and light weight. By using a narrow-band full-duplex transmission line of 200 Kb / s or less as the transmission line, voice and moving images can be bidirectionally communicated, and moving images of the face, facial expressions, and movements of the other party while talking by voice. Can be seen.

FIG. 6 is a block diagram of the embodiment shown in FIG. 5, and reference numerals 6 to 17 in the figure correspond to FIG.
Reference numeral 18 is an A / D converter for audio signals, 19 is an audio information compressor, 20 is a D / A converter for audio signals, 21 is an audio information decoder, and 22 is audio input / output information and moving image input / output information. It is a synthesizer / distributor. Both voice and video information are integrated to realize bidirectional communication using a single narrow band transmission line.

(5) Description of Effects As described above, according to the present invention, the number of pixels of a moving image is 1/10 that of a conventional standard television communication device.
To reduce the physical size of the screen
By adopting a configuration in which the physical pixel density of the screen is increased by reducing it to 1/10 ² , it is possible to realize a moving image communication device capable of both information compression of a moving image and psychological satisfaction with image quality. . By using this device, a moving image communication service using a narrow band transmission line with a transmission rate of 200 Kb / s or less becomes possible. Further, according to the present invention, since it is naturally easy to adapt to miniaturization of each part, it is easy to miniaturize and reduce the weight of the entire apparatus.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a conventional television communication device, FIG. 2 is a screen configuration diagram of a conventional television receiver, and FIG. 3 is a psychological clarity and a screen condition of a moving image in an embodiment of the present invention. 4 is a block diagram of an embodiment showing the basic concept of the present invention, FIG. 5 is an embodiment of the present invention, FIG. 6 is a block diagram of the embodiment shown in FIG. Is. 1-TV camera, 2-compression encoder, 3-transmission path, 4-
Decoder, 5-TV receiver, 6-moving image input section, 7-input side frame memory, 8-information compressor, 9-transmission line, 1
0-decoder, 11-output side frame memory, 12-display section, 13-solidification input section, 14-solidification display section, 15-
Audio output unit, 16-audio input unit, 17-transmission line, 18-
A / D converter, 19-speech information compressor, 20-D / A converter, 21-speech information decoder, 22-information synthesizer / distributor.

Continuation of the front page (56) Reference JP-A-54-34710 (JP, A) Actually developed Shou-50-76714 (JP, U) JP-B-43-11404 (JP, B1) JP-B-51-11455 (JP , B1) “Basics and Applications of Liquid Crystal Electronics” edited by Akio Sasaki Ohmsha (Published April 25, 1979) P. 150, Figures 6.8 Hideo Sato et al., "Image Transmission and Its Equipment," Corona Publishing Co., Ltd. (Published April 20, 1977) P. 270

Claims (2)

[Claims] 1. In a narrow band moving image communication system for transmitting and receiving a moving image using a narrow band transmission line having a transmission speed of 200 Kb / s or less, a transmitting end receives an input from an image pickup device including a solid-state sensor such as a CCD. A moving image input means for decomposing the moving image into pixels and accumulating the pixels, and at the receiving end, at least moving image display means having a display for displaying the pixels of the moving image obtained by the moving image input means, The number of pixels of the moving image displayed on the display and the screen area of the display are 1.2M.
The maximum number of pixels that can be communicated through a broadband transmission line of b / s or more is displayed, and the number of pixels of a moving image is 1 as compared with a normal television communication device of 10 to 20 inches having a predetermined clarity. / 10, 1/1 for screen area
0 ² are selected to a value lowered, narrowband moving picture communication method is characterized in that in order to maintain the same clarity as the normal television communication device. 2. In a narrow band moving image communication apparatus for transmitting and receiving a moving image using a narrow band transmission line having a transmission rate of 200 Kb / s or less, a moving image input from an image pickup device including a solid-state sensor such as CCD is used as a pixel. The moving image input means for decomposing and storing the moving image, the input means for the audio information, the compressing means for the image information and the audio information of the moving image, the image information and the audio information for the moving image, and Means for transmitting to the narrow band transmission path, and further receives from the narrow band transmission path the image information and the audio information of the moving image transmitted by the same means as the respective means at the other end of the narrow band transmission path. Means for distributing the image information and audio information of the moving image, decoding means for the image information and audio information of the distributed moving image, output means for the audio information decoded by the decoding means, and decoding by the decoding means Done A moving image display means having a display device for displaying pixels of the moving image, and the number of pixels of the moving image displayed on the display device of the moving image display means and the screen area of the display device are 1.2 Mb. The maximum number of pixels that can be communicated by a broadband transmission line of / s or more is 1 and the number of pixels of a moving image is 1/100 as compared with a normal television communication device of 10 to 20 inches having a predetermined clarity. 10, the screen area is selected to be a value reduced to 1/10 ² , and is configured to maintain the same intelligibility as that of the normal television communication device, and each of the means is housed in the same housing. A narrow-band video communication device characterized by being integrated.