Digital Watermarking Digital Watermarking: Principles and Practices Dr. Latha Parameswaran AMRITA University India.

Digital Watermarking

Digital Watermarking: Principles and

Practices

Dr. Latha ParameswaranAMRITA University

India

April 21, 2023

Digital Watermarking: Latha Parameswaran

Significance

Vast multimedia content in Internet

Availability of economical and simple tools - easy to pirate

and alter contents

Secure Intellectual Property Rights (IPR)

Digital Rights Management (DRM

Achieved using INFORMATION HIDINGAchieved using INFORMATION HIDING

April 21, 2023


Motivation

Motivation

The distribution of digital media is becoming faster,

easier and requiring less effort to make exact copies

How to protect the intellectual propertyHow to protect the intellectual property?

Conventional approaches

In analog world: signature, steel seal,

embossed portrait, copyright label...

In digital world: Cryptology, Watermarking

April 21, 2023


Significance: Sample Scenario

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Information Hiding

Information Hiding is a general term

encompassing many sub disciplines

Two important sub disciplines are:

Steganography and watermarking

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Solutions Available

Steganography - the art of

concealed communication

Watermarking - the practice of

hiding a message in a media

Cryptography - the practice of

keeping messages secret

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What is a Watermark ?

A distinguishing mark or device impressed in the substance of a sheet of paper during manufacture, usually barely noticeable except when the sheet is held against strong light

to make forgery more difficult to record the manufacturer’s trademark

April 21, 2023


Watermarking - Framework

Digital WatermarkDigital Watermark:

- piece of information hidden in a multimedia content - imperceptible to a human observer, but, easily detected by a computer

Watermarking:Watermarking:

- process of hiding the watermark imperceptibly in the content.

Encryption:Encryption:

- protects content during the transmission of the data from the sender to receiver - after decryption, the data is not protected

WATERMARKING COMPLEMENTS ENCRYPTIONWATERMARKING COMPLEMENTS ENCRYPTION

April 21, 2023


Digital Watermark ?

A digital watermark

a digital signal or pattern imposed on a digital

document ( text, graphics, multimedia presentations ) visible watermark

the more obvious means of discouraging unauthorized use by reducing the commercial value of a document

invisible watermark the watermark is imperceptible to the human eye when the ownership of data is in question, the

watermark will then be extracted to characterize the ownership

April 21, 2023


Watermarking History

More than 700 years ago - Italy - indicate the paper brand and the mill that produced it

18th century - used as anti counterfeiting measures on money and other documents

Term “Watermark” - introduced - end of the 18th century.

First example – similar technology - patent filed in 1954 by Emil Hembrooke - identifying music works

In 1988, Komatsu and Tominaga appear to be the first to use the term “Digital Watermarking”

Since 1995, WATERMARKING ERAWATERMARKING ERA ….

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Watermarking Definition

A practice of imperceptibly altering a cover to embed a message about that cover

Often used whenever the cover is available to parties who know the existence of the hidden data and may have an interest in removing it – additional notion of resilience against attempts to remove the hidden data

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Basic Design of a Watermarking System

Originalwork

Message(regarding

work)

Watermarkembedder

Watermarkedwork

(looks likeoriginal)

Watermarkdetector

Detectedmessage

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Watermarking Applications

1. 1. Copyright protectionCopyright protection Most prominent application Embed information about the owner to prevent

others from claiming copyright Require very high level of robustness

2. 2. Copy protectionCopy protection Embed watermark to disallow unauthorized

copying of the cover For example, a compliant DVD player will not

playback or copy data that carry a “copy never” watermark

3. 3. Content Authentication Embed a watermark to detect modifications to

the cover The watermark in this case has low robustness,

“fragile”

April 21, 2023


Watermarking Applications …

4. 4. Transaction TrackingTransaction Tracking

Embed a watermark to convey information

about the legal recipient of the cover

This is useful to monitor or trace back illegally

produced copies of the cover

This is usually referred to as “fingerprinting”

5. 5. Broadcast MonitoringBroadcast Monitoring

Embed a watermark in the cover and use

automatic monitoring to verify whether cover

was broadcasted as agreed

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Watermarking Characteristics

ImperceptibilityImperceptibilityThe modifications caused by watermark

embedding should be below the perceptible threshold

RobustnessRobustnessThe ability of the watermark to resist

distortion introduced by standard or malicious data processing

SecuritySecurityA watermark is secure if knowing the

algorithms for embedding and extracting does not help unauthorized party to detect or remove the watermark

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Watermarking Characteristics

PayloadPayload The amount of information that can be

stored in a watermark

Informed (non oblivious, or private)Informed (non oblivious, or private) The original un watermarked cover is

required to perform the extraction process

Blind (oblivious, or public)Blind (oblivious, or public) The original un watermarked cover is

NOT required to perform the extraction process

April 21, 2023


Challenges in Watermarking

Making the watermark robust is not trivial

with complete knowledge

any watermark can theoretically be removed

with partial knowledge

the removal may interfere with the viewing of

the data

the effort of removal is greater than the value of

the data

Challenges from data compression

Whatever hole one may find to fill with

watermark is likely to be eliminated by data compression

Capacity

Robustness

Imperceptibility

April 21, 2023


Attacks

Signal enhancement (sharpening, contrast enhancement, etc.)

Additive and multiplicative noise (gaussian, uniform, etc.)

Filtering (High pass, low pass, linear, nonlinear, etc.)

Lossy compression (JPEG, MPEG-x, etc.)

Geometric transforms (RST)

Data reduction (cropping, clipping, etc.)

D/A and A/D conversion (print-scan, etc.)

Multiple watermarking, Collusion attack, Mosaic attack

April 21, 2023


Watermarked Image

Transmission

Corrupted Watermarked Image

Transmission

Lossy Compression

Geometric Distortions

Signal Processing

D/A - A/D Conversion

Typical Distortions or Intentional Tampering

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Types of Watermarks

Perceptibility: Visible / Invisible

Robustness: Fragile/ Semi Fragile/ Robust

Extraction Method: Blind / Informed

Inserted Media: Text / Audio/ Video

Watermark: Noise / Image

Processing Domain: Spatial / Frequency

April 21, 2023


Visible watermark Invisible watermark

Random sequence watermark

Visually recognizable watermark

Digital watermark

Watermark :

Verification :

ID number (random ID number (random number)number)

Quantitative measurement Quantitative measurement of the detectionof the detection

Visually recognizable Visually recognizable patternpattern

Extracted pattern & Extracted pattern & Quantitative measurementQuantitative measurement

April 21, 2023


Watermarking Types

Private or non-blindPrivate or non-blind

requires host image or watermark during

watermark extraction

Semi-private or semi-blindSemi-private or semi-blind

does not require the host image but requires

watermark for extraction

Public or blindPublic or blind

does not require host or watermark for extraction

April 21, 2023


Another classification

Robust watermarkingRobust watermarking

resist legitimate, content-preserving, unintentional

modifications

Applications: copyright protection and content tracking

Fragile watermarkingFragile watermarking

are sensitive, to the slightest modification of the watermarked

image

Applications: Content Authentication in sensitive documents like

medical images

Semi-fragile watermarkingSemi-fragile watermarking

tolerates some degree of legitimate modifications

identify regions of suspected alterations

Applications: Content Authentication

April 21, 2023


Performance Evaluation Metrics(after embedding)

Difference distortion metricsDifference distortion metrics

Mean Square Error (MSE)Mean Square Error (MSE)

Peak Signal to Noise Ratio (PSNR)Peak Signal to Noise Ratio (PSNR)

Image Fidelity (IF)Image Fidelity (IF)

Correlation-based metricsCorrelation-based metrics

Normalized Cross Correlation (NCC)Normalized Cross Correlation (NCC)

Pearson Correlation Coefficient (PCC)Pearson Correlation Coefficient (PCC)

2*2

1

IIn

MSE

I 210

maxlog10

22

*

1

I

II

2

*

I

II

)()( *22

**

II

IIII

April 21, 2023


Performance Evaluation Metrics(after extraction)

Linear Correlation

Normalized Correlation

CorrelationCoefficient

i

iwiwN

wwLC )()(1

),( '*'*

i

iwiwNC )(~)(~ '*

*

**~

w

ww

)~,~( '* wwNCCC

)(~ *** www

'

''~w

ww

'''~ www

April 21, 2023


Watermarking Phases

1. Watermark Embedding

Embed watermark in watermark carriers (DCT,

DWT, …) of the host data May be corrupted by noise, compressed, etc.

during transmission

2. Watermark Extraction

Extract the embedded watermark from the

carriers Extracted watermark may vary from embedded

Compute the watermark from the received data

Measure closeness by metrics like correlation

April 21, 2023


Watermarking - overview

I*

Watermarked image

Modified watermarked

image

Extracted watermark

W*

Host image

IWatermarkembedding

Unintentional and intentional

modifications

Watermark extraction

I’

April 21, 2023


Watermark Generation and Embedding

I*I*

Modified Modified watermarked watermarked

imageimage

I’I’

Watermarked Watermarked imageimage

WW Watermark Watermark

Host imageHost image

ComputeComputefeaturesfeatures

EmbedEmbedthe watermarkthe watermark

(watermark (watermark carriers – DCT, carriers – DCT,

DWT…)DWT…)

Select features and Select features and generate watermarkgenerate watermark(spatial domain or (spatial domain or transform domain)transform domain)

II

Unintentional and Unintentional and intentional intentional

modificationsmodifications

April 21, 2023


Watermark Extraction and Authentication

W*W*

NoNo

YesYes

W’W’

Modified Modified watermarked watermarked imageimage

ComputeComputefeaturesfeatures

ExtractExtractthe embeddedthe embedded

watermarkwatermark

Select features and Select features and generate watermarkgenerate watermark

I’I’

W’ W’ ≈W*?≈W*?

Image is Image is authenticauthentic

Image is Image is unauthenticunauthentic

April 21, 2023


Watermark Generation

Compute salient features of the image

in spatial domain like edges, texture,

fractal dimensions

in transform domain such as singular

values, eigenvalues

random binary sequence

digital signature

other features

April 21, 2023


Watermark Carriers

Embed watermark in watermark carriers:

Discrete Fourier Transform (DFT)

Discrete Walsh-Hadamard Transform

(DWHT),

Discrete Cosine Transform (DCT) and

Discrete Wavelet Transform (DWT)

April 21, 2023


Watermark Embedding

1. Quantization approach

quantize the original data using a

quantization function

determine embedding strength using

minimal distance method

Related work

[2], [10], [55], and [62]–[64]

April 21, 2023


Watermark Embedding

2. Modulation approach

I denotes the host image I* denotes the watermarked image W denotes the watermark α denotes embedding strength

April 21, 2023


Watermark Extraction and Verification

Three step process:

1. Extract the embedded watermark from the received image

2. Compute watermark from the received image using the same watermark generation procedure

3. Compare extracted watermark with the computed watermark using the correlation metric - Verification

Non- blind, Semi-blind, Blind

April 21, 2023


April 21, 2023


Sample Scenarios

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Sample Scenarios

April 21, 2023


Sample Scenario

April 21, 2023


Sample Scenario

April 21, 2023


Sample Scenario

April 21, 2023


Sample Scenario

April 21, 2023


What next ?

Is the interest warranted?

What are the existing and potential commercial

applications of this technology?

What scientific progress has been made in the past

10 years?

What are the most exciting areas for research?

Where might the next 10 years take us?

April 21, 2023


Current Standards

The CPTWG (Copy Protection Technical Working Group)

tested watermarking systems for protection of video on

DVD disks.

The SDMI (Secure Digital Music Initiative) made

watermarking a core component in their system for music

protection.

Two projects sponsored by the European Union, VIVA and

Talisman, tested watermarking for broadcast monitoring.

The ISO (International Organization for Standardization)

took an interest in the context of designing advanced

MPEG standards. (MPEG-21)

April 21, 2023


Problems Faced

Initial expectations of watermarking are too high Security against intentional efforts to remove a

watermark from content

Request for proposal met specifications Slow adoption of watermarking techniques

Mainly due to the diverge business interests of the three industry groups Content owner Manufacturers of consumer electronics Manufactures of computers

Is the current business and academic interest in watermarking warranted?

April 21, 2023


Business Perpective

Can watermarking provide economic solutions

to real problems?

Current business interests

Security Current watermark solutions are of weak

sucurity, but suitable for many business models

Device control No security threat or requirements

Linking traditional media to the Web is receiving

increased attention.

April 21, 2023


What is in research?

Some advances are in their infancy, and much work

remains to be done.

Some results are imminent, making an area exciting.

While in other cases, no breakthroughs are found on the

horizon.

Possible research topics Informed embedding

Geometric/temporal distortions in a blind detector

Optimally embedding with fidelity and robustness constraints

Whether a watermarking system can be designed that permits

public detection while preventing an adversary form removing

the watermark. (The authors are divided in this problem)

April 21, 2023


Conclusion

No standards have been derived An exhaustive list of open

problems A significant area of research Wide applications Industry – Academia relation

builder

April 21, 2023


Digital Watermarking Digital Watermarking: Principles and Practices Dr. Latha Parameswaran AMRITA University India.

Documents

term digital watermarking

digital world

documentsterm watermark

protectionembed watermark

watermarking era

digital document text

ownership of data

hidden data basic design