In recent years, there has been known a technique which makes it possible to mutually share not only a video of a counterparty, but also a desktop screen of a terminal or a screen of an application in a remote communications system such as a teleconferencing system, a web conferencing system, etc., which use a network.
Moreover, when a part of an image is specified in a server which shares a screen, an image whose position/size is the same as that of the specified part is displayed on a screen of a client terminal (Patent document 1).
On the other hand, with respect to a terminal which uses the remote communications system, diversification is in progress, such as a PC which is reduced in size and weight (for example, a Netbook), a tablet terminal, a smartphone, etc.
In the web conferencing system, which is one of the remote communications systems, it is a common usage form that, while sharing a screen of presentation material, a presenter makes an explanation along the material to conference participants.
In the web conferencing, from a display capability of a screen sharing server which shares a screen with other client terminals, that of a client terminal in which a shared screen is displayed may differ. Therefore, when an image size of original image data which is shared from the server side exceeds the number of pixels displayable on the client terminal side, for example, in a screen of the client terminal, a part of an image is chipped off, so that it cannot be displayed. Moreover, when the screen of the client terminal is small, for example, a letter displayed on the screen becomes too small, so that it is difficult to see contents of shared material.
In Patent document 1, with an operation of a user of a server (a presenter), a screen whose position and size is the same as a screen on which the part of the image specified on the server side is displayed on the client side.
However, it is common for the web conferencing to be conducted remotely, so that it is not realistic for the presenter to check display capabilities of screens of multiple client terminals and perform screen displaying for each terminal in accordance with a display capability of a screen on the counterparty side, causing material to be shared difficult to see depending on the display capability of the screen on the counterparty side.
Patent document 1: JP2006-172193A