A Comparative Study of Chaotic and White Noise Signals in Digital Watermarking

Digital Watermarking is an ever increasing and important discipline, especially in the modern electronically-driven world. Watermarking aims to embed a piece of information into digital documents which their owner can use to prove that the document is theirs, at a later stage. In this paper, performance analysis of watermarking schemes is performed on white noise sequences and chaotic sequences for the purpose of watermark generation. Pseudorandom sequences are compared with chaotic sequences generated from chaotic skew tent map. In particular, analysis is performed on highpass signals generated from both these watermark generation schemes, along with analysis on lowpass watermarks and white noise watermarks. This analysis focuses on the watermarked images after they have been subjected to common image distortion attacks. It is shown that signals generated from highpass chaotic signals have superior performance than highpass noise signals, in the presence of such attacks. It is also shown that watermarks generated from lowpass chaotic signals have superior performance over the other signal types analysed

Image Watermarking With Better Resilience

We present schemes for hardening image watermarks against adversarial jamming. Our techniques improve upon standard correlation- and spread spectrum-based methods, and withstand various image distortions and attacks intended to render watermarks unreadable. The watermarking schemes we propose explicitly locate and amplify watermark data remaining after attacks. Key ideas include embedding of watermarks in specially chosen domains, application of image enhancement, computation of responses over watermark subsets, and use of redundancy and search. For watermark detection, our schemes do not require the original image or any information about it