Book Overview

Unlimited number of replicas of the original content can be made from unprotected digital content. Once content is decrypted and copied, there is no protection offered. This situation calls for technological solutions to be used in addition to the cryptography technology. Digital Watermarking technologies have evolved as a major solution for the resolution. This group of technologies provides methods to “imprint” additional data or messages into multi–media contents such as still image, video and audio data. Generally, the imprinted data is invisible (or inaudible) to the ordinary users, and is difficult to be separated from the host media. The imprinted data can be extracted, but not removed, from the imprinted host media by the legitimate owner, as and when required. Watermarking has the notion of robustness against attacks. Even if the existence of the hidden information is known it should be difficult, for an attacker to destroy the embedded watermark completely, even if the algorithmic principle of the watermarking method is public. The watermarking techniques modify the host data for incorporation of the watermark. This modification results in distortion of the host multimedia data. Original and modified images are perceptually equivalent. On the other hand, in medical, military and legal imaging applications, where the need for authentication is often supreme for such applications, lossless data embedding is required. What is Digital Watermark? Digital Watermarking is a technique whereby a pattern of bits are inserted into a digital image, audio, video or text file that identifies the file′s copyright information (author, rights, etc.).The name comes from the faintly visible watermarks imprinted on stationary that identify the manufacturer of the stationery. The purpose of digital watermarks is to provide copyright protection for intellectual property that′s in digital format for inserting visible marks in images & video and for adding information about audio in audio clip etc.