This article introduces some algorithms for motion detection and tracking. To be able to track moving objects, the analysis rate must be fast enough in order to keep the considered movements slow (and the features of the objects not changing too fast).We are presenting a Markov Random Field based motion detection algorithm running in real time on Pentium II and DSP C6x. For the medium level, we have developed a fast labeling algorithm, a benchmark is provided. The high level is fast because the previous processing steps are running at a faster rate than the video rate.