The NEMESIS project targets the applications of professional digital video post-production and new multimedia editing. This project relies on a new powerful content-based image sequence representation scheme to make possible the use of cutting edge image analysis tools in the domain of multimedia contents production. NEMESIS proposes to integrate and to develop automatic image analysis/synthesis techniques providing a set of objects (e.g. regions, layers and 3D objects over time), from sequences of monocular natural images. The NEMESIS project will develop a coherent software platform allowing new functionnalities for image sequence manipulation outperforming existing post-production tools.