The paper is focused on the evolution of the watermarking schemes from pixel-based approaches to content based methods. Firstly, the field of watermarking is presented, its implication in the real word is outlined. The second section gives a brief overview of different approaches in the spatial and the frequential domain. We then present different content-based approaches used to improve the invisibility or the synchronisation of the mark. The last section describes our content-based scheme; the synchronisation of the mark after image processing lies in the use of feature point detectors. The image is decomposed into a set of triangles and each triangle is individually marked, (C) 2001 Pattern Recognition Society. Published by Elsevier Scie...