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Title of Thesis

Watermarking of Medical Images for Content Authentication and Copyright Protection

Author(s)

Nisar Ahmed Memon

Institute/University/Department Details
Faculty of Computer Science and Engineering / GIK Institute of Engineering Sciences and Technology, Topi
Session
2010
Subject
Computer Science
Number of Pages
195
Keywords (Extracted from title, table of contents and abstract of thesis)
Medical, Watermarking, Authentication, Protection, Copyright, Content, Images, Paradigm, Teleconsulting, Manipulated, Compromising, Interest

Abstract
Due to development of latest technologies in the areas of communication and computer networks, present businesses are moving to the digital world for e ectiveness, convenience and security. One of the examples is in the area of medical applications, where traditional diagnosis is being replaced by e-diagnosis. This paradigm gave birth to number of applications in healthcare industry like teleconsulting, telesurgery and telediagnosis. All these applications require the exchange of medical images in digital format from one geographical location to another throughout the globe via a cheap and fast network such as Internet. However, digital form of medical image can easily be manipulated through image processing softwares.Insurance companies, hospitals as well as patients might want to modify the medical images for a number of reasons. The tampered images may be used for illegal purposes.
The objective of this dissertation is to investigate how to protect a medical images, detect tampered images and recover the original image using the technique of Digital Watermarking. Watermarking tech- nology can be categorized into robust, fragile and semi-fragile watermarking, each serving for di erent purposes. In order to facilitate sharing and remote handling of medical images, we propose techniques to solve the problem of copyright protection and content authentication using robust and fragile watermarking respectively.
In the rst part of this dissertation, we design a fragile watermarking system for the exact authentication of medical images. The proposed system authenticates the computed tomography (CT) scan medical images of thorax area against di erent distortions. The system rst enhances the embedding capacity of a CT scan image by isolating the actual lung parenchyma unlike classical watermarking techniques, which use logical square or ellipse for isolating region of interest (ROI). Secondly it embeds watermark only in region of non interest (RONI), thus not compromising the diagnosis value of medical image. The method utilizes the spatial domain watermarking and least signi cant bit (LSB) replacement method for embedding the watermark. Experimental results reveal that the proposed system detects both legitimate and illegitimate distortions.
Robust watermarks are well suited for copyright protection because they stay intact with the image under various manipulations. In the second part of the dissertation, we investigate an approach of robust watermarking for protection of medical images which ensures the security of medical images against geomet- rical distortions. In the proposed method we rstly normalize the medical image using image moments in order to make it invariant against geometric transformations. Secondly, we select the salient regions in the normalized image based on feature points detected by Harris corner detector. Watermarking is performed in Discrete Cosine Transform (DCT) domain of salient regions by adapting block based embedding. The scheme is completely blind, that it does not require the original image to detect the watermark. We thus address the issue of tolerating a ne transformations in medical images that is hardly be found in existing schemes of medical image watermarking.
In third part of the dissertation, we investigate the complete reversible watermarking system. The proposed method uses integer wavelet transform and companding technique which can embed and recover the secret information as well as can restore the image to its pristine state. The method takes advantage of block based watermarking and iterative optimization of threshold for companding, which avoids histogram pre and post-processing. Consequently, it reduces the associated overhead usually required in most of the reversible watermarking techniques. As a result, it keeps the distortion small between the marked and the original images. Experimental results show that the proposed method outperforms the existing reversible data hiding schemes reported in the literature.

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 CONTENTS
 

 

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73 KB
2 1 INTRODUCTION

1.1 Statement of the Problem
1.2 Emerging use of Telemedicine and Need of Protecting Medical Information
1.3 Issues to be Investigated
1.4 Main Contributions
1.5 Organization of Thesis

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87 KB
3 2 LITERATURE REVIEW

2.1 Digital Image Watermarking
2.2 Properties of Digital Watermarking
2.3 Watermarking Domains
2.4 Robust Watermarking Systems
2.5 Fragile Watermarking
2.6 Geometric Attacks Resilient Robust Watermarking
2.7 Medical Image Watermarking

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4 3 WATERMARKING FOR EXACT AUTHENTICATION

3.1 Introduction
3.2 Related Work
3.3 Proposed Scheme
3.4 Experimental Results
3.5 Summary

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577 KB
5 4 AFFINE TRANSFORM RESILIENT WATERMARKING FOR COPYRIGHT PROTECTION

4.1 Introduction
4.2 A ne Transformations
4.3 Image Normalization
4.4 A ne Transform Resilient Watermarking Approaches
4.5 Salient Feature Based Watermarking
4.6 Generation of Invariant Regions
4.7 Block-based embedding
4.8 Proposed Scheme
4.9 Experimental Results and Discussions
4.10 Summary

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800 KB
6 5 REVERSIBLE WATERMARKING FOR EXACT RECOVERY OF ORIGINAL IMAGE

5.1 Introduction
5.2 Literature Review
5.3 Fixed Threshold based Companding
5.4 The Proposed Adaptive Threshold based Reversible Watermarking Scheme
5.5 Experimental Results and Discussions
5.6 Summary

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882 KB
7 6 CONCLUSIONS AND FUTURE DIRECTIONS

6.1 Conclusions
6.2 Future Directions

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62 KB
8 7 BIBLIOGRAPHY AND APPENDIX

 

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