Abstract
This paper presents a new approach for digital image watermarking which resists both geometric attacks and calibration signal removal attack. Firstly, the synchronization problem of classical watermarking methods and related work are addressed. The class of synchronization using calibration signal including template pattern, feature-based, and periodic embedding is elaborated. Then, we show the synchronization method using calibration signal cannot resist calibration signal removal attack because the calibration signal has no protection. To protect the calibration signal, we propose a key-dependent synchronization method, where the calibration signal and the function of synchronization are protected by a secret key. In this way, any unauthorized attacker without the secret key can no longer find the calibration signal and is unable to destroy the synchronization by the calibration signal removal attack. Moreover, we employ a periodic message embedding technique to synchronize both the global transformation and local deformation simultaneously. The experimental results demonstrate the proposed method is robust to both geometric attacks and calibration signal removal attack. For calibration signal removal attack, since the spectrum of watermark distortion is near a noise, an attacker cannot find the calibration signal and the calibration signal removal attack is ineffective. For geometric attacks, we perform more severe geometric attacks than Stirmark and the detection results show the proposed method is robust to the severe geometric attacks even when visual quality of the attacked image is seriously distorted.