Abstract: To improve the robustness and security performances of watermarking, a selfadaptive watermarking synchrorization schemewas proposed. In the scheme, the connected objects are obtained according to image connectivity, and the gravity centers ofbigger objects are selected as the reference points forwatermark embedding. Selfadaptive synchronization ofwatermark detection is ensured by the topological invariability of image connectivity and the stability of its gravity center. The high stablility of the reference points for watermark embedding makes watermarks robust not only under common image processing but also under global and local geometrical attacks.