@device(postscript)
@libraryfile(Mathematics10)
@libraryfile(Accents)
@style(fontfamily=timesroman,fontscale=11)
@pagefooting(immediate, left "@c<Technical Report 1996>",
center "@c<Computer Science>",
right "@c<Carnegie Mellon>")
@heading(Focus of Attention in Video Conferencing)
@heading(CMU-CS-96-150)
@center(@b(Jie Yang, Leejay Wu, Alex Waibel))
@center(June 1996)
@center(FTP: CMU-CS-96-150.ps.gz)
@blankspace(1)
@begin(text)

In this report we present an approach to low bitrate video teleconferencing by 
focusing attention on important information. We show that by selectively 
degrading the quality of less important regions, more important regions can be 
sent without loss of quality but with greatly reduced bandwidth requirements. 
Low bitrate transmission for real-time video delivery over a dynamic network 
is achieved by region blurring and cropping. A prototype system has been 
developed
to demonstrate the concept. We assume that a human facial area is the most 
interesting area in the system. The system can automatically focus its 
attention 
on a given face and its adjustable surrounding area. The selected area is then 
fed 
to the coding system and sent to the receiver. The selection function of the 
system
is fulfilled by a real-time face tracker. The face being tracked can be 
selected 
by a mouse or finger pointing if a touch screen is used. It can track a 
person's 
face while the person moves freely (e.g., walking, jumping, sitting and 
rising) in 
a room. Based on the information provided by the face tracker and the network 
traffic, a window surrounding the face can be determined. The window size can 
reflect the network traffic. The image outside of the window will be either 
cropped or blurred. The preprocessed image is then fed to a tele-conferencing 
software package - vic, a real-time multimedia application for video 
conferencing 
over the Internet. The experimental results show significant savings of 
required 
bandwidth for video subjected to the changes.

@blankspace(2line)
@begin(transparent,size=10)
@b(Keywords:@ )@c<Video tele-conferencing, Low bitrate, focus of attention,
face tracking, real-time tracking>
@end(transparent)
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@end(text)
@flushright(@b[(30 pages)])