JP2592983B2 - Video conference system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention connects conference rooms at distant locations via a communication line, and mutually transmits images and voices, so that a plurality of people hold a conference. Video conference system for

[Prior art] With the development and spread of digital transmission lines represented by ISDN,
With the advance of image processing technology and the development of high-speed digital signal processing technology, in recent years, demands for realizing various image communication services have been extremely increased. Among these, one of the most promising services is the video conference service.

Videoconferencing connects conference rooms between remote locations via a communication line, and transmits information such as images, voices, and documents in two directions, thereby sharing these information, and is the same as in the same conference venue. The meeting is held in a simple environment, and time and geographical constraints can be easily overcome.

Among information handled in a video conference, particularly, image information has a large amount of information, has a strong real-time property, and has a large effect on a sense of reality in a video conference.

Generally, in a video conference, image information is first converted to a digital signal, then subjected to redundancy suppression coding by appropriate processing, compressed to an information amount suitable for a transmission path, and transmitted to a communication line.

FIG. 3 shows a schematic block diagram of a configuration of an image information processing section of a conventional video conference system.

An image signal from an image input device such as a television camera is input to an image input unit 31, where preprocessing such as A / D conversion and filter processing is performed. The digitized image signal is subjected to redundancy suppression encoding in an image encoding unit 33, encoded into a code string having an appropriate amount of information, and transmitted to a line through a transmission path control unit 34.

The code sequence received from the line is decoded by the image decoding unit 35 via the transmission line control unit 34, and the digital image signal is restored. This image signal is subjected to post-processing such as D / A conversion and filter processing in an image output unit 37, and is output to a display or the like, where an image is displayed.

Also, in a video conference system, it is generally said that displaying 3 to 4 people on one screen is the limit to be able to determine the facial expressions of the participants. In such a case, a method of inputting an image using a separate television camera or the like, synthesizing a screen, and transmitting the image is performed.

Hereinafter, an example of the operation when performing image composition will be described.

Image signals from the two television cameras are sent from the image input unit 31 to the image synthesis unit 32, respectively. FIG. 4 (a)
As shown in the figure, the input screen from the two systems of television cameras is a full view screen showing the whole view partially including a necessary display target. In the image synthesizing unit 32, as shown in FIG. 4 (a), upper and lower quarters of each input screen are removed, and
Is extracted. These two screens are vertically combined as one screen (hereinafter, referred to as a space division mode) and sent to the image encoding unit 33. On the receiving side, the image signal decoded by the image decoding unit 35 is sent to the image separation unit 36. In the image separation unit 36, the screen synthesized vertically on the transmission side is separated again into two screens, and each of the screens is separated into two screens.
From different displays.

As another combining method, a method of switching the input system for each image frame as shown in FIG. 4B (hereinafter, referred to as a time division mode) can be considered. At this time, the image combining unit 32
Switches the image input system for each frame and sends it to the image encoding unit 33.

On the contrary, the image separation unit 36 on the receiving side switches the output system for each frame and performs display. The time division mode is equivalent to an operation of multiplexing and transmitting two independent systems of images on a transmission path.

[Problems to be Solved by the Invention] However, in the video conference system, if the space division mode is used, the entire screen cannot be transmitted. Therefore, it is necessary to transmit the entire screen as in a zoom-up operation of a caller. In some cases, only one system of input image can be transmitted.

In the case of the time-division mode, since the transmission path is divided and used in each image system, only half of the transmission path capacity used for one input image is allocated, and the transmitted image is transmitted. However, there is a problem that the transmission path of a higher band is required to obtain a high quality image.

The present invention has been made in view of the above points, and when combining screens from a plurality of input systems and transmitting the combined screens as one screen, an appropriate screen combining method is selected to efficiently reduce the capacity of the transmission path. It is an object of the present invention to provide a video conference system for realizing a video conference with a simple configuration, which can be realized at a low transmission cost and has a realistic sense.

[Means for Solving the Problems] In order to solve the above-mentioned problems, according to the present invention, there are provided an image input unit for inputting two systems of image signals, and an image synthesizing unit for synthesizing two systems of input image signals into one system. Image encoding means for encoding the composite image signal; transmission path control means for transmitting or receiving encoded image data to or from the transmission path; and image decoding means for decoding the received image data. Image separation means for separating the decoded image signal into two systems, image display means for displaying the separated image signals on a display device, respectively, and the two systems of input images according to the content of the image to be transmitted and received. The signal is divided into regions for each image frame, and necessary portions are extracted from the divided regions and combined into one image frame, or two types of image frames are formed from the one image frame. A mode switching unit that selects a space division mode for separating and a time division mode for combining or separating by switching an input system for each image frame, and switches a mode of the image combining unit and the image separating unit. A video-conference system wherein a space-division mode is set when an area is divided into one image frame for each image frame of the two-system image signal, and a time-division mode is used otherwise. It is.

[Operation] In the mode switching section 18, when both inputs are full-screen images, it is necessary to switch to the space division mode to transmit an image and transmit the full screen such as a zoom-up screen. In some cases, the mode is switched to the time division mode to transmit an image.

Thus, even during communication, an appropriate method of synthesizing a screen can be selected in accordance with an image, so that advantages of each screen synthesizing method can be utilized.

[Example] Next, an example of a video conference system according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic block diagram of the configuration of the image information processing unit of the video conference system of the present invention.

The operations of the image input unit 11, the image encoding unit 13, the transmission path control unit 14, the image decoding unit 15, and the image output unit 17 are the same as those of the conventional video conference system.

The video conference system of the present invention includes a mode switching unit 18. In the mode switching unit 18, when both inputs are both full-screen images, the image is transmitted by switching to the space division mode, and when it is necessary to transmit the entire image such as a zoom-up image, etc. The image is transmitted by switching to the time division mode.

Hereinafter, an example of the operation when performing screen composition will be described. FIG. 2 shows an example of screen composition.

Each of the two television cameras captures a panoramic image of three or four persons.
Are combined and transmitted as upper and lower regions of the screen in the space division mode.

When the screen from one TV camera changes to the speaker's zoom-up screen, etc., and it becomes necessary to transmit the entire screen,
The mode switching unit 18 instructs the image combining unit 12 to switch the screen combining method from the space division mode to the time division mode. That is, the image synthesizing unit 12 changes the operation so that the zoom-up screen from one television camera and the whole view screen from the other television camera are switched and transmitted frame by frame.

At this time, it is sufficient to transmit the entire screen for the zoom-up screen and 1/2 of the screen with the upper and lower quarters removed for the whole view screen, so that more capacity of the transmission path can be allocated to the zoom-up screen. Thus, better image quality can be obtained than in the normal time division mode.

When the images from both television cameras are returned to the full view screen again, the mode switching unit 18 sends an instruction to the image combining unit 12 to change the operation to combine the screens in the space division mode.

On the receiving side, the reverse operation may be performed, and when the screen is synthesized in the space division mode,
In the image separation section 16, the combined screen is separated into upper and lower parts, and each is displayed and output.

When the mode on the transmission side is changed to the time division mode, the mode switching unit 18 instructs the image separation unit 16 to change the operation mode. Then, the image separating section 16 operates to sort the output system for each frame of the transmitted image.

[Effects of the Invention] As described above, according to the video conference system of the present invention, the method of synthesizing the screen can be adaptively changed during communication depending on the content of the image to be transmitted. It can respond to transmission.

In addition, the capacity of the limited transmission path can be used more efficiently.

Therefore, it is possible to provide a highly versatile and realistic TV conference system without increasing the transmission cost.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing an example of switching of the mode of screen composition according to the present invention, and FIG. FIG. 4 is a schematic block diagram showing a configuration example, and FIG. 4 is a diagram showing an example of synthesizing screens. 11 image input unit 12 image synthesis unit 13 image encoding unit 14 transmission line control unit 15 image decoding unit 16 image separation unit 17 image output unit 18 mode switching unit

Claims (1)

(57) [Claims] 1. An image input means for inputting two systems of image signals, an image synthesizing means for synthesizing two systems of input image signals into one system, an image coding means for coding a synthesized image signal, Transmission line control means for transmitting or receiving the decoded image data to or from the transmission line, image decoding means for decoding the received image data, and image separation means for separating the decoded image signal into two systems Image display means for displaying the separated image signals on a display device; and dividing the input image signals of the two systems into image frames for each image frame in accordance with the content of the image to be transmitted and received. A space division mode for taking out the necessary parts and combining them into one image frame, or separating two systems of image frames from the one image frame, and switching the input system for each image frame. And a mode switching unit for switching between the modes of the image synthesizing unit and the image separating unit, and a mode switching unit for switching between the modes of the image synthesizing unit and the image separating unit.
A video conference system in which a space division mode is set when a region is divided and synthesized into one image frame, and a time division mode is set otherwise.