digital watermarking

Presented by : Zahra Shokrollahi

Winter of 1393 1

TABLE OF CONTENTS

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Introduction

Watermarking History

Steps in Watermarking

Types of Digital Watermarking

Digital Watermarking Techniques(1)

Digital Watermarking Techniques(2)

Purpose of Watermarking

Conclusion

References

INTRODUCTION

• Information Hiding Techniques

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Information Hiding

Steganography Cryptography Watermarking

INTRODUCTION :WHAT IS DIGITAL WATERMARKING?

• Digital watermarking is an extension of watermarking concept in the digital world.

• A digital watermark is a pattern of bits inserted into a digital image, audio or video file that

identifies the file's copyright information (author, rights, etc.).

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INTRODUCTION :HOW WATERMARKING IS DIFFERENT FROM STEGANOGRAPHY AND

CRYPTOGRAPHY

Steganography vs. Watermarking

• The main goal of steganography is to hide a message m in some audio or video (cover) data d,

to obtain new data d', practically indistinguishable from d, by people, in such a way that an

eavesdropper cannot detect the presence of m in d'.

• The main goal of watermarking is to hide a message m in some audio or video (cover) data d,

to obtain new data d', practically indistinguishable from d, by people, in such a way that an

eavesdropper cannot remove or replace m in d'.

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INTRODUCTION :HOW WATERMARKING IS DIFFERENT FROM STEGANOGRAPHY AND

CRYPTOGRAPHY (CONT.)

Cryptography vs. Watermarking

• Cryptography is the most common method of protecting digital content and is one of the best

developed science.

• However, encryption cannot help the seller monitor how a legitimate customer handles the

content after decryption.

• Digital watermarking can protect content even after it is decrypted.

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WATERMARKING HISTORY

• The idea of hiding data in another media is very old, as described in the case of steganography.

The term "digital watermark" was first coined in 1992 by Andrew Tirkel and Charles Osborne

presented two techniques to hide data in images. These methods were based on modifications

to the least significant bit (LSB) of the pixel values.

• Watermarks are identification marks produced during the paper making process. The first

watermarks appeared in Italy during the 13th century, but their use rapidly spread across

Europe. They were used as a means to identify the papermaker or the trade guild that

manufactured the paper. Watermarks continue to be used today as manufacturer's marks and

to prevent forgery.

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STEPS IN WATERMARKING

Embedding Attack Extraction/Detection

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STEPS IN WATERMARKING (CONT.)

Embedding

• In embedding, an algorithm accepts the host and the data to be embedded, and produces a

watermarked signal.

• Inputs to the scheme are the watermark, the cover data and an optional public or secret key.

The output are watermarked data. The key is used to enforce security.

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STEPS IN WATERMARKING (CONT.) :EMBEDDING

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STEPS IN WATERMARKING (CONT.)

Attacks

• The watermarked digital signal is transmitted or stored, usually transmitted to another person. If

this person makes a modification, this is called an attack.

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STEPS IN WATERMARKING (CONT.)

Few Possible Attacks

• Robustness attacks :Which are intended to remove the watermark such as JPEG compression,

cropping, etc.

• Presentation Attacks :Under watermark detection failure they come into play. Geometric

transformation, rotation, scaling, translation, change aspect ratio, affine transformation etc.

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STEPS IN WATERMARKING (CONT.)

Extraction/Detection

• Detection (often called extraction) is an algorithm which is applied to the attacked signal to

attempt to extract the watermark from it. If the signal was unmodified during transmission,

then the watermark still is present and it may be extracted.

• Inputs to the scheme are the watermarked data, the secret or public key and, depending on the

method, the original data and/or the original watermark.The output is the recovered

watermarked W or some kind of confidence measure indicating how likely it is for the given

watermark at the input to be present in the data under inspection.

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STEPS IN WATERMARKING (CONT.) :EXTRACTION

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TYPES OF DIGITAL WATERMARKING

Robust & Fragile Watermarking

Visible & Invisible Watermarking

Public & Private Watermarking

Asymmetric & Symmetric Watermarking

Steganograhic & Non-Steganographic watermarking

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TYPES OF DIGITAL WATERMARKING (CONT.)

Robust & Fragile Watermarking

• Robust Watermarking:-Modification of watermarked content will not affect watermark.

• Fragile Watermarking:-Watermark get destroyed when watermarked content is modified or

tampered with.

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TYPES OF DIGITAL WATERMARKING (CONT.)

Visible & Invisible Watermarking

• On Visible watermarking, contents are visible

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TYPES OF DIGITAL WATERMARKING (CONT.)

• Invisible watermarking are not viewed on just looking

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TYPES OF DIGITAL WATERMARKING (CONT.)

Public & Private Watermarking

• Public Watermarking

• Users of content are authorized to detect watermark

• Private Watermarking

• Users not authorized to detect watermark

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TYPES OF DIGITAL WATERMARKING (CONT.)

Asymmetric & Symmetric watermarking

• In Asymmetric watermarking different keys used for embedding and detecting watermark

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TYPES OF DIGITAL WATERMARKING (CONT.)

• In symmetric watermarking same keys are used for embedding and detecting watermarks

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TYPES OF DIGITAL WATERMARKING (CONT.)

Steganographic & Non-Steganographic Watermarking

• Steganographic Watermarking

• User unaware of the presence of a watermark

eg:-Used in finger printing applications

• Non-Steganographic WM:-

• User aware of the presence of a watermark.

e.g.:-Used to detect piracy

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DIGITAL WATERMARKING TECHNIQUES(1)

LSB Watermarking

Color Separation Technique

Bit Stream Watermarking

Word Space Coding, Line Space Coding & Character Coding

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DIGITAL WATERMARKING TECHNIQUES(1) (CONT.)

LSB Watermarking

• Lower order bits of selected pixels in the image are used to store watermarks.

• Replacing lower order bits of each pixel with higher order bit of different image.

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DIGITAL WATERMARKING TECHNIQUES(1) (CONT.)

Color Separation Technique

• Watermark appears only in one of the color bands

• Used to watermark in images

• Can be extended to moving images

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DIGITAL WATERMARKING TECHNIQUES(1) (CONT.)

Bit Stream Watermarking

• Used in audio watermarking

• Data is directly inserted into compressed audio files

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DIGITAL WATERMARKING TECHNIQUES(1) (CONT.)

Word Space Coding, Line Space Coding & Character Coding

• Used for watermarking in text documents

• In word space coding, the spaces between words are altered to embed watermark code. In line

space coding the space between the lines are altered and in character coding some of the

characters are imperceptibly modified (i.e., made larger, serifs enhanced, etc).

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DIGITAL WATERMARKING TECHNIQUES(2)

• The previous techniques were in spatial domain . Also in frequency domain , we have some

techniques such as FFT , DCT , FHT , DWT , SWT , beyond wavelet transforms and etc.

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PURPOSE OF WATERMARKING

Copyright Protection

•Copyright owner wants to check for illegal copies of her works

Finger printing

•Hidden serial numbers. It enable the intellectual property owner to identify which customer broke his license agreement.

Copy Control

•Copyright owner wants to control the terms of use of her work

•Example : DVD protection(Copy once, Copy many, No copy)

Broadcast Monitoring

•Monitor when and whether content is transmitted over broadcast channels, such as TV or radio(Verify advertising broadcasts, Verify royalty payments, Catching instances of piracy)

Data Authentication

•Watermark is used to detect modification applied to cover work

•Example : Checking for fraud passport photographs

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CONCLUSIONS

• DRM (Digital Rights management) systems and content management are important for

protection of rights of digital multimedia creations that are distributed on the Internet. Digital

watermarking is an effective technique for embedding rights information in digital multimedia

data.

• Digital watermark technology can be used in consumer electronic devices like digital still

camera, digital video camera, DVD players, MP3 players, etc., for various applications like

providing controlled access, preventing illegal replication and watermark embedding.

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REFRENCES

• www.google.com

• www.wikipedia.org

• www.watermarkingworld.org

• www.ukessays.com

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