Design and Implementation of a DCT-Based Robust Digital Image Watermarking Scheme

摘要

The advent of digital media has brought a giant breakthrough in the 21st Century.The milestone of digital media is marked by the way in which it has become an integral part of our everyday lives.Digital media allows for the easy and efficient storage of high-quality information that can be as well transmitted efficiently using relatively cheap channels without any significant loss in quality or fragments of the information.The nature of digital media also allows for fast and easy manipulation.Its predecessor,analog media suffered from certain significant disadvantage that have been remedied in digital media.Quality is one distinctive difference between the two forms of media.Digital media allows for higher quality audio,image and video information to be stored and transmitted while analog media fails to offer such possibilities.Manipulation of digital is also much easier and efficient as it allows for targeting specific discrete locations within the media that require modification.Lossless copying with the ability to retain fidelity is also one key advantage that is offered in digital media.This is to say that one copy of an original digital media will be identical to the original copy.While encryption algorithms may offer a way of restricting access to digital media copies,encryption in itself possess intrinsic flaws which makes them vulnerable.Once an encryption algorithm has been successfully broken through decryption,the digital content that was to be protected is left open to unauthorized copying and unlawful redistribution.
　　Image processing offers a solution to the above stated problem.Image processing allows hiding ownership data in the targeted media content which is not lost in the process of copying and therefore can allow for the ascertaining of ownership in subsequent copies of an original file.The concept of watermarking which has already been implemented in currencies allows for verification of the authenticity of a bank note.In the same way,this watermarking can be applied to digital multimedia,allowing for the authentication of copies of an original digital content.All multimedia can be regarded as digital signals and hence can be treated and processed using signal processing methods and algorithms.This nuance allows for defining watermarking as the technology that allows for embedding ownership information into a digital signal which can subsequently be used in verification of the authenticities of copies,they-by establishing proof of ownership of the digital material.In the scope of digital media,piracy is the act of unlawful acquisition,copying,editing or redistribution of digital content without proper regard and reference to the original owner or creator of the content.A pirate is then defined as one that deals in digital piracy.A digital piracy will therefore attempt to remove a digital watermark in order to violate copyrights or attempt to forge the proof of authenticity of the material.
　　This has inspired extensive research work that is aimed towards the development of robust watermarking schemes that make it harder for the removal of embedded rights information within digital content and hence,prevent serious infringements on copy-written material.
　　This thesis discusses the design and implementation of an invisible and robust waternarking scheme for digital images.The implementation of the discussed scheme is achieved using Matlab as an implementation platform.The implemented system is designed with a graphical user interface (GUI) for proper user interaction.In order to achieve robustness,the implementation relies on a spectral watermarking approach using the Discrete Cosine Transform as a premise.The selection of the DCT for implementation is based on an in-depth literature review of background work which is also presented here in the thesis.In order to verify the robustness of the system,we conduct some experiments using common watermarking attacks such as noise addition,scaling,cropping and compression.

目录

封面

英文摘要

致谢

目录

Chapter 1 Introduction

1.1 Basic Watermarking Concepts

1.2 Variants of Watermarking Introduction

1.3 Applications of Watermarking

1.4 Background

1.5 CONCLUSION

CHAPTER 2 Literature Review

2.1 Conclusion

CHAPTER 3 Proposed Invisible and Robust DCT-Based Watermarking Scheme

3.1 INTRODUCTION

3.2 DISCRETE COSINE TRANSFORMATION

3.3 DESIGN AND IMPLEMENTATION OF DCT-BASED WATERMARKING SYSTEM IN MATLAB

3.4 EXPERIMENTAL TESTING

3.5 PERFORMANCE EVALUATION

3.6 ROBUSTNESS

3.7 CONCLUSION

Chapter 4 DISCUSSION

Chapter 5 CONCLUSION

参考文献