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ABSTRACT
Today’s world is digital world. Nowadays, in every field there is enormous use of digital contents. Information handled on INTERNET and MULTIMEDIA NETWORK SYSTEM is in digital form. The copying of digital content without quality loss is not so difficult. Due to this, there are more chances of copying of such digital information. So, there is great need of prohibiting such illegal copyright of digital media. Digital watermarking (DWM) is the powerful solution to this problem. Digital watermarking is nothing but the technology in which there is embedding of various information in digital content which we have to protect from illegal copying. This embedded information to protect the data is embedded as watermark. Beyond the copyright protection, Digital watermarking is having some other applications as fingerprinting, owner identification etc. Digital water-marks are of different types as robust, fragile, visible and invisible .Application is depending upon these watermarks classifications. There are some requirements of digital watermarks as integrity, robustness and complexity.
INTRODUCTION:
Digital documents i.e. documents created in digital media are having certain
Advantages like-
• Efficient data storage, duplication, manipulation and transmission.
• Copying without loss.
Such digital documents consist of images, audio clips and videos etc. But due
to some delimits of digital documents, they become inefficient to use. These
delimits are as follows
• Illegal copying
• Falsification(duplication)
• No copyright protection
• No ownership identification
The large use of networked multimedia system has created the need of “Copyright Protection”for different digital medium as images, audio clips, videos etc. The term “Copyright Protection” involves the authentification of ownership and identification of illegal copies of digital media. Though digital media provides various efficient facilities like distribution, reproduction and manipulation of images, audio clips and videos, they increase illegal copying of digital media.
The solution for this problem is to add the visible or invisible structure to digital media which is to be protected from copyright. These structures are known as “Digital Watermarks” and the process of adding digital watermarks to digital media is known as “Digital Watermarking”.
Digital watermarking is created by inserting a digital signal or pattern into digital content. Digital watermarking is nothing but process of conveying information by imperceptibly embedding it into digital media. The purpose of embedding the information depends upon application and need of user of digital media. Digital watermarking provides the solution for difficult problem of providing guarantee to organizer and consumer of digital content about their legal rights. Copyright protection for multimedia information is nothing but a golden key for multimedia industry. Digital watermarking is a technology that opens a new door for authors, producers, publishers and service providers for protection of their rights and interest in multimedia documents.
There are various techniques for prevention of illegal copying. They are described as follows
1. Encryption methods which includes use of public and private keys to
encode the data, so that image can decoded only with required key.
2. Site security methods which includes use of firewalls to access the data.
3. Using Thumbnail images. and the most popular and important
4. Digital watermarking which includes robust labeling of an image with
Information which is to be prevent from illegal copying and also use of image checksum or other techniques to detect manipulation of image data.
In general sense, Digital Watermarking means “Author Signature”.
Digital watermarking is the process of encoding hidden copyright information in an image by making small modifications in it’s pixel content. In this case watermarking doesn’t restrict the accessing image information. The important function of watermarking is to remain present in data for proof of ownership. The use of digital watermarking is not restricted up to copyright
Protection. Digital watermarking can also be used for owner identification to identify content of owner, fingerprinting to identify buyer of content, broadcast monitoring and authentification to determine whether the data is changed from it’s original form or not Finally, the actual meaning of Digital watermarking technique is come to know from following three point of views
1. Work: A specific song, video, picture or specific copy of such.
2. Content: Set of all possible works.
3. Watermarking: The practice of imperceptibly altering a work to embed a message about that work. The watermarking solution promise to protect your images by inserting text information and then tracking the images. Digital watermarking distinguishes digital copies and mark documents with owner’s ID.There are many reasons to embed information in digital content using digital watermarking. The internet boom is one of the reasons. It has become very easy to connect to internet from home computers to obtain or provide various information using World Wide Web(WWW). All information handled on internet is in digital form. Such digital content can be copy such that new file is indistinguishable from original one. Then content can be reproduce in large quantities. .Digital watermarking protecting such illegal copying. A watermark discourages piracy and determines criminals of making illegal copies of digital media.
CHAPTER NO.2
WHAT IS AND WHY TO USE DWM?
2.1 What is it?
Digital watermarking is an adaptation of the commonly used and well known paper watermarks to the digital world .Digital watermarking describes methods and technologies that allow to hide information. The hiding process has to be such that the modifications of the media are imperceptible. Digital watermarking is a technology for embedding various types of information in digital content. In general, information for protecting copyrights and providing the validity of data is embedded as watermark. Digital watermarking is relatively a new way of protecting intellectual property However, theories and technologies behind it are computer based steganography, cryptography; spread spectrum communications and noise theory.
2.2Why to use it?
First important application come into mind is copyright protection of digital media. It is easy to duplicate digital data exactly without quality loss. Similar to process in which artist signed their painting with a brush to claim their copyrights, artist of today can watermark their work and hide some information say their name in the image. Hence, embedded watermark will allow to identify the owner of work. This concept is applicable to digital video and audio also.
Especially, distribution of digital audio over internet in MP3 format is currently a big problem. Digital watermarking may be useful to setup controlled audio distribution and provide efficient means for copyright protection, usually in collaboration with international registration bodies such as IDDN (Inter Deposit Digital Number).
In addition with copyright protection, Digital watermarking is playing a important role in many fields of applications such as broadcast monitoring, owner identification, transaction tracking, proof of ownership, fingerprinting, content authentification, copy control, device control. Digital watermarks can also serve as invisible labels and content link. For example, photo development labs may insert a watermark into the picture to link the print to it’s negative. so, it is becomes easy to find out negative of a print. All one has to do is to scan the print and extract the information from negative. In a completely different scenario, the digital watermarks may be used as a geometrical reference which may be useful for programs such as Optical Character Recognition(OCR) software. The embedded calibration watermark may improve the detection reliability of the OCR software since it allows the determination of translation, rotation and scaling.
Digital watermarking also serves as a means of advertising within the digital media. For instance, the user may download and view a digital image, use a watermark reader to extract the digital signature, then access a web based directory to find the company’s name and up-to-date address, phone number and web and e-mail address. Digital watermarks also serves the purposes of identifying quality and assuring authenticity. A graphic or audio file bearing digital watermark can inform the viewer or listener who owns to the item.
PROPERTIES AND CLASSIFICATION OF DWM:
3.1 Properties:
For better activeness, watermark should be –perceptually invisible within host media, statistically invisible to unauthorized removal, readily extracted by owner of image, robust to accidental and intended signal distortion like filtering, compression, resembling, retouching, crapping etc. For a digital watermark to be effective for ownership, it must be robust, recoverable from a document, should provide the original information embedded reliably and also removed by authorized users.
All these important properties of digital watermarks are described as-
1. Robustness: The watermark should be robust such that it must be difficult to remove. The watermark should be robust to different attacks.
The robustness describes whether watermark can be reliably detected after performing some media operations.
2. Perceptual transparency: This property describes that whether watermark is visible or invisible to human sensor organ. Perceptible watermarks are visible to human while imperceptible are not. Imperceptible watermarks are such that content remains same after applying digital watermarking technique.
3. Security: Security property describes that how easy to remove a watermark. This is generally referred to as “attack” on watermarking. Attack refers to detection or modification of watermark.
4. Complexity: This is important property which is to be considering in real time applications like video. Complexity property is concerned with amount of effort needed to extract or retrieve the watermark from content.
5. Capacity: Capacity property of digital watermarks refers to amount of information that can be embedded within the content. The important point is that more data is used in watermark, watermark will become less robust.
In addition to these properties, watermarks are having some extra properties asunambiguity, tamper resistance, inseparable from the works and able to undergo some transformation as works.
3.2Classification:
Digital watermarks are classified according to their applications. The watermarks are classified as perceptible watermarks and imperceptible watermarks, robust and fragile, public and private. This classification of watermarks is broadly described in following sections.
1. Perceptible watermarks and imperceptible watermarks:
Perceptible watermarks are visible to human eye while imperceptible watermarks are invisible. The perceptible watermarks are useful for primary application i.e. for statement ownership or authorship.So for this reason it should be visible. .On the other hand imperceptible watermarks are useful for complex applications such as document identification in which content being watermarked must appear in unchanged from Examples of visible (perceptible) watermarks are logos on TV,IBM’s watermark and that of invisible(imperceptible) watermarks are ATT,NEC/MIT,UU etc.
Perceptible watermarks i.e. visible one are extension of the concept of logos .They are applicable to images only. These watermarks are embedded into image. They are applicable in maps, graphics and software user interface. Imperceptible watermarks i.e invisible one remains hidden in the content. They can be detected only by authorized agency .These watermarks are useful for content or author authentication and for detecting unauthorized copier.