Region-of-interest based adaptation of video to mobile devices

The goal of this work is to develop methods for the adjustment of video in standard definition resolution to the smaller resolution used in mobile devices. The naive solution is to scale each frame to the desired size. But, objects must be at a sufficient size to be recognized easily. Therefore, it was suggested in previous works to display only a Region Of Interest (ROI). In this work we focus on news broadcasting and interview scenes, so the ROI contains the speaker's face. At the beginning of every scene, the ROI is marked by an editor. We present a novel algorithm for tracking the ROI. The algorithm estimates the global motion caused by the camera and the local motion caused by the speaker's movements. We estimate the motion parameters using horizontal and vertical projections. The slice-projection theorem and the Mellin transform are used for reducing complexity.