Robust Image Content Authentication with Tamper Location

We propose a novel image authentication system by combining perceptual hashing and robust watermarking. An image is divided into blocks. Each block is represented by a compact hash value. The hash value is embedded in the block. The authenticity of the image can be verified by re-computing hash values and comparing them with the ones extracted from the image. The system can tolerate a wide range of incidental distortion, and locate tampered areas as small as 1/64 of an image. In order to have minimal interference, we design both the hash and the watermark algorithms in the wavelet domain. The hash is formed by the sign bits of wavelet coefficients. The lattice-based QIM watermarking algorithm ensures a high payload while maintaining the image quality. Extensive experiments confirm the good performance of the proposal, and show that our proposal significantly outperforms a state-of-the-art algorithm.