DigitalWatermarking-InterimReport-TheUniversityofTexasat.ppt

Digital Watermarking-Interim Report (EE5359: Multimedia processing) Under the Guidance of Dr. K. R. Rao Submitted by: Ehsan Syed 1000671971 seaquadri@ The University of Texas at Arlington – Spring 2011 Introduction Digital watermarking is based on the science of steganography [1] or data hiding. Steganography comes from the Greek meaning ‘covered writing’. Steganography is defined as the practice of undetectably altering a work to embed a secret message. It is an area of research of communicating in a hidden manner. Introduction.. Steganography and watermarking rely on imperfections of human senses. The human eye has a limited dynamic range so low quality images can be hidden within high quality images [2]. Basic Principle There are three main stages in the watermarking process [3]: generation and embedding attacks retrieval/detection Generation and Embedding Generation of watermarks is an important stage of the process. Watermarks contain information that must be unique otherwise the owner cannot be uniquely identified. In embedding, an algorithm accepts the host and the data to be embedded and produces a watermarked signal. Various algorithms have been developed so far [4-13]. Attacks The watermarked signal is then transmitted or stored, usually transmitted to another person If this person makes a modification, this is called an attack. There are many possible attacks. Retrieval/Detection Detection is an algorithm which is applied to the attacked signal to attempt to extract the watermark from it. If the signal was not modified during transmission, then the watermark is still present and it can be extracted. Block diagram Fig.1: Basic block diagram of digital watermarking Types of watermarking There are mainly three types of watermarking [14]: Visible watermarking Invisible watermarking Dual watermarking Techniques of watermarking There are two major techniques of watermarking [15]: Spatial domain: slightly modifies the pixels of one or two rand