Watermarking 1

8/14/2019 Watermarking 1

1/20

Watermarking

IT6902;SemesterB,2004/2005;Leung


2/20

Information Hiding:Information Hiding:SteganographySteganography and Watermarkingand Watermarking

Dr. Mohammed AlDr. Mohammed Al--MuallaMualla and Prof.and Prof. HussainHussainAlAl--AhmadAhmad

Multimedia Communication and Signal Processing (MCSP)Multimedia Communication and Signal Processing (MCSP)

Research GroupResearch Group

EtisalatEtisalat College of EngineeringCollege of EngineeringP.O.Box: 980,P.O.Box: 980, SharjahSharjah, UAE, UAE

Tel: +971 6 5611333, Fax: +971 6 5611789,Tel: +971 6 5611333, Fax: +971 6 5611789,

ee--mail: {mail: {almuallaalmualla,, alahmadalahmad}@}@eceece.ac..ac.aeae


3/20

OutlineOutline

Introduction to Information HidingIntroduction to Information Hiding

SteganographySteganography

Definition and HistoryDefinition and History

ApplicationsApplications

Basic PrinciplesBasic Principles

Examples of TechniquesExamples of Techniques DemosDemos

WatermarkingWatermarking

Definition and HistoryDefinition and History

ApplicationsApplications


RequirementsRequirements

AttacksAttacks Evaluation and BenchmarkingEvaluation and Benchmarking

ExamplesExamples


4/20

Information HidingInformation Hiding

Information HidingInformation Hiding is a general term encompassingis a general term encompassingmanymany subdisciplinessubdisciplines

Two importantTwo important subdisciplinessubdisciplines are:are: steganographysteganography andandwatermarkingwatermarking

SteganographySteganography:: Hiding: keeping theHiding: keeping the existenceexistence of the information secretof the information secret

Watermarking:Watermarking:

Hiding: making the informationHiding: making the information imperceptibleimperceptible

Information hidingInformation hiding is different thanis different than cryptographycryptography(cryptography is about(cryptography is aboutprotectingprotecting the content ofthe content of

messages)messages)


5/20


DefinitionDefinition Watermarking:Watermarking: is the practice of imperceptibly altering a cover tois the practice of imperceptibly altering a cover to

embed a message about that coverembed a message about that cover

Watermarking is closely related toWatermarking is closely related to steganographysteganography, but there are, but there aredifferences between the two:differences between the two: In watermarking the message isIn watermarking the message is relatedrelated to the coverto the cover

SteganographySteganography typically relates totypically relates to covert pointcovert point--toto--point communicationpoint communication

between two partiesbetween two parties Therefore,Therefore, steganographysteganography requires onlyrequires only limited robustnesslimited robustness

Watermarking is often used whenever theWatermarking is often used whenever the cover is availablecover is available to partiesto partieswhowho know the existenceknow the existence of the hidden data and may have anof the hidden data and may have an interest ininterest inremoving itremoving it

Therefore, watermarking has the additional notion ofTherefore, watermarking has the additional notion ofresilienceresilience againstagainstattempts to remove the hidden dataattempts to remove the hidden data

Watermarks areWatermarks are inseparableinseparable from the cover in which they arefrom the cover in which they areembedded. Unlike cryptography, watermarks can protect contentembedded. Unlike cryptography, watermarks can protect contenteveneven afterafter they are decodedthey are decoded


6/20


HistoryHistory More than 700 years ago, watermarks were used in Italy to indicaMore than 700 years ago, watermarks were used in Italy to indicatete

the paper brand and the mill that produced itthe paper brand and the mill that produced it

By the 18By the 18thth century watermarks began to be used ascentury watermarks began to be used asanticounterfeitinganticounterfeiting measures on money and other documentsmeasures on money and other documents

The term watermark was introduced near the end of the 18The term watermark was introduced near the end of the 18thth century.century.

It was probably given because the marks resemble the effects ofIt was probably given because the marks resemble the effects ofwater on paperwater on paper

The first example of a technology similar to digital watermarkinThe first example of a technology similar to digital watermarking isg isa patent filed in 1954 by Emila patent filed in 1954 by Emil HembrookeHembrooke for identifying musicfor identifying music

worksworks In 1988, Komatsu andIn 1988, Komatsu andTominagaTominaga appear to be the first to use theappear to be the first to use the

term digital watermarkingterm digital watermarking

About 1995, interest in digital watermarking began to mushroomAbout 1995, interest in digital watermarking began to mushroom


7/20


ApplicationsApplications1.1. Copyright protectionCopyright protection

Most prominent applicationMost prominent application

Embed information about the owner to prevent others from claiminEmbed information about the owner to prevent others from claiminggcopyrightcopyright

Require very high level of robustnessRequire very high level of robustness

2.2. Copy protectionCopy protection Embed watermark to disallow unauthorized copying of the coverEmbed watermark to disallow unauthorized copying of the cover

For example, a compliant DVD player will not playback or copy daFor example, a compliant DVD player will not playback or copy datatathat carry a copy never watermarkthat carry a copy never watermark

3.3. Content AuthenticationContent Authentication

Embed a watermark to detect modifications to the coverEmbed a watermark to detect modifications to the cover

The watermark in this case has low robustness, fragileThe watermark in this case has low robustness, fragile


8/20


ApplicationsApplications4.4. Transaction TrackingTransaction Tracking

Embed a watermark to convey information about the legalEmbed a watermark to convey information about the legalrecipient of the coverrecipient of the cover

This is useful to monitor or trace back illegally producedThis is useful to monitor or trace back illegally producedcopies of the covercopies of the cover

This is usually referred to as fingerprintingThis is usually referred to as fingerprinting

5.5. Broadcast MonitoringBroadcast Monitoring

Embed a watermark in the cover and use automaticEmbed a watermark in the cover and use automaticmonitoring to verify whether cover was broadcasted asmonitoring to verify whether cover was broadcasted asagreedagreed


9/20



Encoder(Embedding)

cover c

Decoder(Extraction)

InsecureChannel(Attacks)

watermark w key k

watermarked datas

watermarked dataS

TRANSMITTER RECEIVER

key k watermark w

orconfidence measure

watermark w orcover c


10/20


RequirementsRequirements ImperceptibilityImperceptibility

The modifications caused by watermark embedding shouldThe modifications caused by watermark embedding shouldbebe below the perceptible thresholdbelow the perceptible threshold

RobustnessRobustness

The ability of the watermark toThe ability of the watermark to resistresist distortion introduceddistortion introducedbyby standardstandard oror maliciousmalicious data processingdata processing

SecuritySecurity

A watermark is secure ifA watermark is secure ifknowing the algorithmsknowing the algorithms forforembedding and extractingembedding and extracting does not help unauthorised partydoes not help unauthorised partyto detect or remove the watermarkto detect or remove the watermark


11/20


RequirementsRequirements PayloadPayload

The amount of information that can be stored in aThe amount of information that can be stored in awatermarkwatermark

Informed (Informed (nonobliviousnonoblivious, or private) Watermarking:, or private) Watermarking:

The originalThe original unwatermarkedunwatermarked cover iscover is requiredrequired to performto performthe extraction processthe extraction process

Blind (oblivious, or public) Watermarking:Blind (oblivious, or public) Watermarking:

The originalThe original unwatermarkedunwatermarked cover iscover is NOT requiredNOT required totoperform the extraction processperform the extraction process


12/20


AttacksAttacks Signal enhancement (sharpening, contrast enhancement, etc.)Signal enhancement (sharpening, contrast enhancement, etc.)

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

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

LossyLossy compression (JPEG, MPEGcompression (JPEG, MPEG--x, H.26x, etc.)x, H.26x, etc.)

Geometric transforms (translation, rotation, etc.)Geometric transforms (translation, rotation, etc.)

Data reduction (cropping, clipping, etc.)Data reduction (cropping, clipping, etc.)

TranscodingTranscoding (MPEG2(MPEG2 H.263, etc.)H.263, etc.)

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

Multiple watermarkingMultiple watermarking

Collusion attackCollusion attack

Mosaic attackMosaic attack


13/20


Evaluation and BenchmarkingEvaluation and Benchmarking

Subjective Evaluation:Subjective Evaluation:

Subject is asked to rate the perceptibility of theSubject is asked to rate the perceptibility of the artefactsartefacts(5=imperceptible, 4=perceptible but not annoying,(5=imperceptible, 4=perceptible but not annoying,3=slightly annoying, 2=annoying, 1=very annoying)3=slightly annoying, 2=annoying, 1=very annoying)

Objective Evaluation:Objective Evaluation:

MSE, SNR, PSNR, NCC, etc.MSE, SNR, PSNR, NCC, etc.

Benchmarking Software:Benchmarking Software:

UnzignUnzign StirMarkStirMark

CheckMarkCheckMark

OptiMarkOptiMark


14/20


EExamplesxamples Informed Watermarking Method of CoxInformed Watermarking Method of Cox et alet al..

Originalimage

DDCT

Extractlargest N

coefficients

key kRandomNumber

Generator

[ ]N

vvv ,,, 21 K=V

Embed

)1(iii

xvv +=

[ ]N

xxx ,,, 21 L=X

Insert backNmodifiedcoefficients

IDCTWatermarked

ImageD

V

ENCODER


15/20


EExamplesxamples Informed Watermarking Method of CoxInformed Watermarking Method of Cox et alet al..

Originalimage

DDCT

Extractlargest N

coefficients

key kRandomNumber

Generator

[ ]N

vvv ,,, 21 K=V

Extract

/)1*

(* =i

i

i

v

vx

[ ]N

xxx ,,, 21 L=X

X*

DECODER

Attackedimage

D*DCT

ExtractNcoeff. fromsame locations

[ ]Nvvv *,,*,** 21K

=V

Calculatesimilaritymeasure

Decision


16/20


EExamplesxamples

original = 0.1 = 0.4 = 0.6

original N= 2000 N= 4000 N= 6000


17/20


EExamplesxamples

original JPEG q=100NC=0.999

JPEG q=80NC=0.993

JPEG q=10NC=0.557

original WatermarkedNC=0.999

CroppedNC=0.672


18/20


EExamplesxamples

Original Image

512 X 512

Watermark

128 X 64

Watermarked

ImageDCT

IDCT

Original Image

512 X 512

Watermarked

ImageDCT

IDCT

Walsh

Coding

128 x 64

DCT-domain

Embeddingwithout

Walsh Coding

DCT-domainEmbedding

withWalsh Coding


19/20


EExamplesxamples


20/20

WatermarkingIT6902;SemesterB,2004/2005;Leung

References

Originalsourceoftheslides:

http://www.emirates.org/ieee/events.html#Digital_Watermarking

Additionalreferences: S. P. Mohanty, "Digital Watermarking: A Tutorial Review", Report, Dept. of

Electrical Engineering, Indian Institute of Science, Bangalore, India, 1999.

http://www.cs.unt.edu/~smohanty/research/Reports/MohantyWatermarkingSurve

y1999.pdf Podilchuk, C.I. and Delp, E.J. "Digital watermarking: algorithms and

applications",IEEE Signal Processing Magazine, Vol. 18, Issue 4, pp.33-46,

July 2001

Perez-Gonzalez, F. and Hernandez, J.R. "A tutorial on digital watermarking",Proc. IEEE 33rd Annual 1999 Int. Carnahan Conf. on Security Technology,

pp.286-292, Oct. 1999

Nikolaidis, N. and Pitas, I. "Digital image watermarking: an overview",IEEE

Int. Conf. on Multimedia Computing and Systems, Vol. 1, pp.1-6, June 1999

Watermarking 1

Documents