DIGITAL WATERMARKING

LECTURE #4

Presented ByMrs.Vasanthi Muniasamy

Overview

Introduction What is Watermarking? What is Digital Watermarking? Behind the Technology. Importance Types of Watermarking. Digital Watermarking Techniques. Applications

Conventional Encryption System

Watermark

“Watermarking can be considered as a special

technique of Steganography where one message is

embedded in another and the two messages are

related to each other in some way. “Example :-

The presence of specific patterns in currency notes

which are visible only when the note is held to light is

a well known example for watermark.

What is Watermarking?

Example of a conventional watermark

Courtesy of Blue Spike, Inc.

Digital Watermarking is originated from Steganography

What is Digital Watermarking?

“Digital watermarking is similar to watermarking

physical objects, except that the watermarking technique

is used for digital content instead of physical objects. “

Digital Watermark

Digital Watermark

In digital watermarking a low-energy signal is imperceptibly embedded in another signal. The low-energy signal is called watermark.

The main signal in which the watermark is embedded is referred to as cover signal since it covers the watermark.

An entity called watermark key used for embedding and detecting watermark signal

Watermark key is private

Behind The Technology

Sending Side …

Watermark Embedding process Water mark Original Image Key Water marked image

Behind The Technology

Watermark retrieval process Water marked image Key Confidential message

Receiving Side …

The Overall System

The Technology Roars…

Importance Of Digital Watermarking

© Copyright Information© On-line music industry© News gathering using digital cameras

Types of Digital Watermarking

Robust & Fragile Watermarking Visible & Invisible Watermarking Public & Private Watermarking Asymmetric & Symmetric Watermarking Steganograhic & Non-Steganographic

watermarking

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

Visible & Invisible Watermarking

On Visible watermarking, contents are visible

Visible & Invisible Watermarking (Contn..)

Invisible watermarking are not viewed on just looking

Public & Private Watermarking

• Public Watermarking

Users of content are authorized to detect watermark

• Private Watermarking

Users not authorized to detect watermark

Asymmetric & Symmetric watermarking

In Asymmetric watermarking different keys used for embedding and detecting watermark

Asymmetric & Symmetric watermarking (Contn..)

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

Steganographic & Non-Steganographic Watermarking

Steganographic Watermarking

User unaware of the presence of a watermark

eg:-Used in finger printing applicationsNon-Steganographic WM:-

User aware of the presence of a watermark.

e.g.:-User to detect piracy

Digital Watermarking Techniques

LSB Watermarking Color Separation Technique Bit Stream Watermarking Word Space Coding, Line Space Coding

&Character Coding

Applications of Digital Watermarking.

Copy ProtectionContent AuthenticationCopyright ProtectionMetadata Tagging

References

www.watermarkingworld.org www.digital-watermark.com