Web based image authentication using invisible Fragile watermark

A Study on Watermarking Schemes for Image Authentication

Abstract: The digital revolution in digital image processing has made it possible to create, manipulate and transmit digital images in a simple and fast manner. The adverse affect of this is that the same image processing techniques can be used by hackers to tamper with any image and use it illegally. This has made digital image safety and integrity the top prioritized issue in today’s information explosion. Watermarking is a popular technique that is used for copyright protection and authentication. This paper presents an overview of the various concepts and research works in the field of image watermark authentication. In particular, the concept of content-based image watermarking is reviewed in details. KeywordsWatermark Lifecycle, Robust Watermarking Schemes, Fragile Watermarking Schemes, HVS, ICA.

Medical Image Authentication through Watermarking Preserving ROI

Abstract: Telemedicine is a well-known application where enormous amount of medical data need to be securely transferred over the public network and manipulate effectively. Medical image watermarking is an appropriate method used for enhancing security and authentication of medical data, which is crucial and used for further diagnosis and reference. This project focuses on the study of medical image watermarking methods for protecting and authenticating medical data. Additionally, it covers algorithm for application of water marking technique on Region of Non Interest (RONI) of the medical image preserving Region of Interest (ROI). The medical images can be transferred securely by embedding watermarks in RONI allowing verification of the legitimate changes at the receiving end without affecting ROI. Segmentation plays an important role in medical image processing for separating the ROI from medical image. The proposed system separate the ROI from medical image by GUI based approach, which works for all types of medical images. The experimental results show the satisfactory performance of the system to authenticate the medical images preserving ROI.

Watermarking of Medical Images for Content Authentication and Copyright Protection

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.

Reversible dynamic secure steganography for medical image using graph coloring

Abstract: Securing data in telemedicine applications is extremely essential and therefore it is mandatory to develop algorithms which preserve the data transmitted. Steganography (information hiding technique) plays a crucial role in telemedicine applications by providing confidentiality, integrity, availability and authenticity. This paper proposes a novel steganography technique that conceals patient information inside a medical image using a dynamic key generated by graph 3 coloring problem. The proposed method ensures reversibility as the original medical image is restored after extracting the embedded data from the stego medical image. Despite the embedding of patient information in the medical image, the visual quality of the image is preserved. Experimental results show that the proposed method is resistant against uniform affine transformations such as cropping, rotation and scaling. The proposed method is designed by considering issues related to transmission errors which could contaminate the medical images transmitted. The performance of the proposed method is compared to other information hiding methods against various parameters such as robustness of stego-image against affine transformations, toughness of the dynamic key generated, detection of transmission error, embedding rate and reversibility.

Techniques for data hiding

Abstract: Data hiding, a form of steganography, embeds data into digital media for the purpose of identification, annotation, and copyright. Several constraints affect this process: the quantity of data to be hidden, the need for invariance of these data under conditions where a "host" signal is subject to distortions, e.g., lossy compression, and the degree to which the data must be immune to interception, modification, or removal by a third party. We explore both traditional and novel techniques for addressing the data-hiding process and evaluate these techniques in light of three applications: copyright protection, tamper-proofing, and augmentation data embedding.

A digital watermark

Abstract: The paper discusses the feasibility of coding an "undetectable" digital water mark on a standard 512/spl times/512 intensity image with an 8 bit gray scale. The watermark is capable of carrying such information as authentication or authorisation codes, or a legend essential for image interpretation. This capability is envisaged to find application in image tagging, copyright enforcement, counterfeit protection, and controlled access. Two methods of implementation are discussed. The first is based on bit plane manipulation of the LSB, which offers easy and rapid decoding. The second method utilises linear addition of the water mark to the image data, and is more difficult to decode, offering inherent security. This linearity property also allows some image processing, such as averaging, to take place on the image, without corrupting the water mark beyond recovery. Either method is potentially compatible with JPEG and MPEG processing. >

Exploring steganography: Seeing the unseen

Abstract: Steganography is the art of hiding information in ways that prevent the detection of hidden messages. It includes a vast array of secret communications methods that conceal the message's very existence. These methods include invisible inks, microdots, character arrangement, digital signatures, covert channels, and spread spectrum communications. Steganography and cryptography are cousins in the spycraft family: cryptography scrambles a message so it cannot be understood while steganography hides the message so it cannot be seen. In this article the authors discuss image files and how to hide information in them, and discuss results obtained from evaluating available steganographic software. They argue that steganography by itself does not ensure secrecy, but neither does simple encryption. If these methods are combined, however, stronger encryption methods result. If an encrypted message is intercepted, the interceptor knows the text is an encrypted message. But with steganography, the interceptor may not know that a hidden message even exists. For a brief look at how steganography evolved, there is included a sidebar titled "Steganography: Some History."

A robust content based digital signature for image authentication

Abstract: A methodology for designing content based digital signatures which can be used to authenticate images is presented. A continuous measure of authenticity is presented which forms the basis of this methodology. Using this methodology signature systems can be designed which allow certain types of image modification (e.g. lossy compression) but which prevent other types of manipulation. Some experience with content based signatures is also presented. The idea of signature based authentication is extended to video, and a system to generate signatures for video sequences is presented. This signature also allows smaller segments of the secured video to be verified as unmanipulated.