Characterization of capture actions in video sequences

This paper deals with automatic characterization of video capture actions like scale change (zoom) or translation (traveling) in a video sequence. The overall objective is to enhance the scripted quality while capturing a video sequence by professionals or non professionals. Ultimately, the capture actions would use a predefined video template, progressively filled by the cameraman and automatically checked against the template scenario by the acquisition system. We focused on the detection of the zoom action. The characteristics of zoom are detected by analyzing pairs of frames of the target sequence. The principle of the method resides in choosing characteristic points into a pair of images, matching them in order to estimate the plane projective transformation using RANSAC method. Once the transformation model has been found, it allows to extract relevant information regarding the scale and the translation factor, necessary to verify the type and also the quality of the realized zoom sequence. We present several experiments that show very promising results.