Τεχνικές προστασίας εικόνων και εικονοσειρών και εφαρμογές υδατογραφίας

Abstract

In the present thesis, protection techniques and watermarking applications for image and video are studied. In particular, initially a new watermarking method is presented, which is suitable for copyright protection in digital images that have undergone geometric attacks. The proposed method is based on generalized Radon transformations and is especially robust to scaling and rotation attacks. Additionally, a fast video watermarking system that operates in the compressed domain and is suitable for multiplexed MPEG- 1/2 video is described. The proposed system detects the watermark using a generalized correlator detector that performs a non-linear preprocessing of the data before detection and outperforms the classic correlator in terms of detection performance. A complete video security system is also proposed, which combines cryptography and watermarking for the secure delivery of MPEG video in CD and DVD. Finally, information embedding in images that are coded using the JPEG2000 coding standard is studied.