Technical advances in recent years have made video videoconferencing a cost effective and increasingly widespread alternative to physical face-to-face meetings. In a typical long-distance video conference, the participants at each station transmit and receive audio and video signals that allow the participants to see and hear each other. In a general sense, a videoconference may also be at a single site, such as a lecture hall, where the audience views a display.
Some videoconferencing stations include a document stand for providing a video signal of a document to be displayed on a monitor as part of the videoconference. A single image of a document is captured for transmission from video provided by the document stand's camera. More technically speaking, a video frame is converted to a frame of data and transmitted as a "slide".
A video conference may include supporting materials other than documents. For example, it may be desirable to present a computer screen display by transmitting the image data from which the display is generated to a larger on-site monitor for audience viewing or to an off-site monitor. Or, it may be desired to present material written on a whiteboard. This could be accomplished with video from a camera viewing the whiteboard, with the video being converted to a frame of data that is transmitted as a slide.
As indicated by the above examples, although the source material may vary, most video videoconferencing systems have at least one means for presenting supporting materials. A general term for such presentations is "still frame images". The slide of the document or other supporting material is a motionless image, and is typically displayed with higher resolution than the video images.
Most videoconferencing systems have a "preview" mode as well as a "slide" mode. In the preview mode, the presenter and perhaps his audience can view a video image of the item being presented as it is being positioned, annotated, or otherwise prepared for discussion.
In the past, both the slide presentation mode and the preview mode have required action on the part of the presenter. The presenter must remember to send the slide at the appropriate time, such as when he or she has finished positioning or annotating the document. If there is a preview mode, the presenter must remember to switch to preview and back to himself when the preview is over and the formal presentation is to begin.