A fragile watermarking algorithm for T-Spline surfaces

T-Spline surface is an important parametric surface, which is widely used in entertainment, engineering, science and medicine. A fragile watermarking algorithm is proposed for integrity authentication of T-Spline surfaces. In this algorithm, some points on T-Spline surfaces are selected by a special algorithm, then the watermark is embedded by modifing the selected points, and then the watermarked surfaces is acquired by modifying the control points with constrained optimization method. The experiment results show that the watermark is fragile to many attacks, and the tampered area can be detected. Additionally, when preprocessing is used before watermark extracting, the algorithm can modified to be semi-fragile that is robust to translating, rotating and uniformly scaling.