Digital Watermarking

Introduction

Types of Digital Watermarking

Working Domain

Human Perspective

Types of Documents

Presentation Outline

Application

Introduction Digital Watermarking Technology

• Allows - Embed Data - Digital Signals

• Secret Message - Embedded - Cover message

• Difficult to Remove

• Knowledge - Secret Key – Allow - Extract • Text, Still Images,Video or Audio Data

• Watermarking - Protect Copyright - Original Owner

• Identification & Authentication

Types of Digital Watermarking

Types Of Documentation

Types Of Documentation

Types of Digital Watermarking

• MP3Stego: WAV -> MPEG-3 + additional Data

• Temporal masking

– 5-20ms before a loud signal

– 50-200ms after a loud signal

Types Of Documentation

Types Of Documentation

Types of Digital Watermarking

Types of Digital Watermarking

Watermarking life-cycle phases

Steps in Watermarking• Embedding Information embedded - digital watermark

Signal where the watermark - embedded - host signal

In embedding, an algorithm accepts host & data - embedded & produces a watermarked signal.

• Attack During transmission, If this person – modification - called attack.

• DetectionAlgorithm applied - attacked or unmodified signal - attempt extract watermark

Working DomainSpatial Domain

• Methods use block x block based watermarking.

• e.g. embed watermarks - randomly selected 8x8 blocks pixels - image.

Frequency domain

• Embed a watermark, frequency transformation - applied - host data

• Modifications - transform coefficients

• Possible frequency image transformations - Discrete Fourier Transform

Human Perspective

Visible watermark:

Information visible - text or logo - identifies - owner - media.

Human Perspective

Invisible watermark:

Invisible watermark - embedded image - cannot be perceived - human’s eyes

Intended -prevent or deter unauthorized copying - digital media.

Invisible Watermarking

Visible Watermarking

A watermark may be:

Fragile: distorted or broken under slight changes

Semi-fragile: designed - break under all changes - exceed

user- specified threshold

Robust: withstand moderate - severe signal processing attacks (compression,rescaling,filtering)

Application1. Copyright protection

• Most prominent application• Embed information - owner - prevent others - claiming copyright• Require very high level of robustness

2. Copy protection

• Embed watermark - disallow unauthorized copying - cover• E.x. compliant DVD player - not playback or copy data - carry “copy

never” watermark

3. Content Authentication

• Embed watermark - detect modifications - cover• Watermark - low robustness, “fragile”

Application4. Transaction Tracking

• Embed watermark - convey information - legal recipient – cover

• Useful - monitor or trace back illegally produced copies – cover

• Referred as “fingerprinting”

5. Broadcast Monitoring

• Embed watermark - cover & use automatic

• Monitoring - verify whether cover - broadcasted as agreed

Conclusion

Digital watermarking focuses on embedding information inside a digital object such that the embedded information is in separable bound to the object.

References

• www.google.com

• www.wikipedia.org

• www.scribd.com

• www.clic2c.com

• www.youtube.com