Digital Image Watermarking

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1. Introduction

Information is becoming widely available via global networks. These connected networks allow cross-references between databases. The advent of multimedia is allowing different applications to mix sound, images, and video and to interact with large amounts of information (e.g., in e-business, distance education, and human-machine interface). The industry is investing to deliver audio, image and video data in electronic form to customers, and broadcast television companies, major corporations and photo arc hivers are converting their content from analogue to digital form. This movement from traditional content, such as paper documents, analogue recordings, to digital media is due to several advantages of digital media over the traditional media. Digital Watermarking Technique is becoming popular, especially for adding undetectable identifying marks, such as author or copyright information. Because of this use, watermarking techniques are often evaluated based on their invisibility, recoverability, and robustness. Our goal was to implement watermarking method and evaluate their susceptibility to attack by various image processing techniques.

1.1 Problem Statement

An important factor that slows down the growth of multimedia networked services is that authors, publishers and providers of multimedia data are reluctant to allow the distribution of their documents in a networked environment. This is because the ease of reproducing digital data in their exact original form is likely to encourage copyright violation, data misappropriation and abuse. These are the problems of theft and distribution of intellectual property. Therefore, creators and distributors of digital data are actively seeking reliable solutions to the problems associated with copyright protection of multimedia data.

1.2 Objectives

Digital watermarking is the process of embedding information into a digital signal in a way that is difficult to remove. The signal may be audio, pictures or video, for example. If the signal is copied, then the information is also carried in the copy. A signal may carry several different watermarks at the same time.

In visible watermarking, the information is visible in the picture or video. Typically, the information is text or a logo which identifies the owner of the media. The image on the right has a visible watermark. When a television broadcaster adds its logo to the corner of transmitted video, this is also a visible watermark.

In invisible watermarking, information is added as digital data to audio, picture or video, but it cannot be perceived as such (although it may be possible to detect that some amount of information is hidden). The watermark may be intended for widespread use and is thus made easy to

Figure I: How Watermarking is done

1.3 Scope

The future development of networked multimedia systems, in particular on open networks like the Internet, is conditioned by the development of efficient methods to protect data owners against unauthorized copying and redistribution of the material put on the network. This will guarantee that their rights are protected and their assets properly managed. Copyright protection of multimedia data has been accomplished by means of cryptography algorithms to provide control over data access and to make data unreadable to non-authorized users. However, encryption systems do not completely solve the problem, because once encryption is removed there is no more control on the dissemination of data.

Our project includes two kinds of watermarking – Visible and Invisible.

In invisible watermarking, the image to be used as watermarked should be black and white and its size should be less than the original image to be watermarked.

When the watermarking is done using invisible watermark approach he size of the watermarked image increases...
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