Comparative Study of Visible Reversible Watermarking Algorithms - Image Security Paradigm

摘要

In recent years, digital watermarking has been studied intensively to provide copyright protection to multimedia data including image, audio and video. While this is usually considered an improvement in everyday lifestyle, it also makes unauthorized copying and distributing of multimedia images, data much easier, therefore presenting a challenge in the field of copyright protection i.e. digital watermarking. To embed the watermark robustly and imperceptibly, watermark bits are added to the significant coefficients of each sub band selected by considering the human visual system characteristics. This paper, surveys the features and concepts pertaining to the three algorithms for visible watermarking capabilities and analyze them with metrics such as MSE and PSNR i.e. a) wavelet based algorithm b) Tian's difference expansion algorithm c) LSB - prediction error expansion algorithm. The experimental results for many Benchmark/Popular test images show that LSB prediction-error expansion doubles the maximum embedding capacity and involves significantly less computational complexity. It shows higher PSNR value but also imposes various stages of difficulty to an intruder who intends to extract the original image from the encrypted sub-blocks when compared to other algorithms.