A Semi-fragile Digital Watermarking Algorithm for 2D Vector Graphics Tamper Localization

A semi-fragile digital watermarking algorithm resisting affine transformation based on 2D vector graphics was designed for tamper localization. We divide graphics vertices after extraction, and then transform the construction of 8 × 8 matrix by DCT; authentication watermark is generated by the relationship between the DCT coefficients, and then embedded in the middle frequency region of the coefficients; pre-processing is proposed to eliminate geometric distortion before detecting. High invisibility, robust against common geometrical distortions (e.g. translation, rotation and scaling) and good capability of tamper localization have been proved by experimental results.