The video applications on mobile communication devices have usually been designed for content creation, access,
and playback. For instance, many recent mobile devices replicate the functionalities of portable video cameras
and video recorders, and digital TV receivers. These are all demanding uses, but nothing new from the consumer
point of view. However, many of the current devices have two cameras built in, one for capturing high resolution
images, and the other for lower, typically VGA (640x480 pixels) resolution video telephony. We employ video to
enable new applications and describe four actual solutions implemented on mobile communication devices. The
first one is a real-time motion based user interface that can be used for browsing large images or documents such
as maps on small screens. The motion information is extracted from the image sequence captured by the camera.
The second solution is a real-time panorama builder, while the third one assembles document panoramas, both
from individual video frames. The fourth solution is a real-time face and eye detector. It provides another type
of foundation for motion based user interfaces as knowledge of presence and motion of a human faces in the view
of the camera can be a powerful application enabler.