Comparative Study of Various Transformations in Robust Watermarking Algorithms

In the digital world, that is currently evolving at such a rapid pace, intellectual copyright protection is becoming increasingly important. This is due to digital data being particularly simple to copy and resell without any loss of quality. Digital representation and distribution of data has increased the potential for misuse and theft and thus gives rise to problems associated with copyright protection and the enforcement of these rights. The main technical approaches to address the challenge of intellectual copyright protection are digital watermarking techniques. The spread spectrum technology has become an important technique that is not only widely used for still image and video watermarking, but also used for audio watermarking.A robust watermarking algorithm to watermark JPEG2000 compressed and encrypted images. The encryption algorithm is proposed to use a stream cipher. While the proposed technique embeds watermark(the transmission of question paper in online for a secure manner) in the compressed-encrypted domain, the extraction of watermark can be done in the decrypted domain. Based upon this application a study made for this transformation such as multiwavelet, contourlet and lifting scheme decomposition and also compare the characteristics of these transformations using LSB technique for various file formats and the spread-spectrum watermarking (SSW) technology. Experimental results show the various characteristics of different transforms, the embedding capacity,robustness, perceptual quality and security of the proposed algorithm, and their efficiency with various image formats in watermarking using LSB algorithm and spread spectrum.