Digital Image Watermarking dwt,dct,fft

7/21/2019 Digital Image Watermarking dwt,dct,fft

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2011-2012

Maleka Hanhan

AN-Najah National University

Faculty of Engineering

Electrical Engineering Department

Graduation Project

Digital Image Watermarking



Table of Contents Table o !igures............................................................................ ............... ..... "

A#$%&W'(D)(M(%T.......................................................................................*

'ist o A+ronyms............................................................................................... ,

'ist o Symbols................................................................................................. ,

#hapter-: Introdu+tion............................................................................... ......

History o /atermarking.............................................................................. --

0e1uirements or /atermarking algorithms:...............................................-2

Importan+e o Digital Watermarking....................................................... .... -3

Aims............................................................................................................... -"

#lassi4+ation o digital /atermark........................................................... ...... -"

5isible /atermarks...................................................................................... -"In6isible /atermark..................................................................................... -"

Appli+ations o digital /atermarking.............................................................. -*

Digital /atermarking te+hnology or rights management...........................-*

Digital watermarking technology for authentication and tamper proofing .................-*

5isible re6ersible /atermarking or ele+troni+ distribution.............. .......... .-,

Watermarking as #ommuni+ation System......................................................-,

DIST&0I&%S A%D ATTA#$S................................................................ ............ -7

0emo6al atta+ks..........................................................................................-7)eometri+al atta+ks.................................................................................... -

#ryptographi+ atta+ks................................................................................. -8

Proto+ol atta+ks.................................................................... .............. ........ -8

Quality Measurements.....................................................................................29

#hapter2: DWT Image /atermarking.......................................................... ...2-

DWT Domain Watermarking........................................................................... 22

Simulation results...........................................................................................23

!irst 'e6el De+omposition.................................................................... ....... 2"

#hapter3: D#T Image /atermarking.............................................................. 28

Introdu+tion.................................................................................................... 39

I%S(0TI&% &! WAT(0MA0$............................................................................39

Simulation result..................................................................................... ....... 3-

Digital Image Watermarking Page 2



#hapter": !!T Image /atermarking............................................................. ..3"

I%S(0TI&% &! WAT(0MA0$............................................................................3*

( tra+ted o /atermark..................................................................................3*

Simulation result..................................................................................... ....... 3,

#omparison bet/een D#T and !!T................................................................38

#on+lusions;;;;;;;;;;;;;;;..;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;."2

Appinde ;;;;;;;;;;;;;;;;.;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;."3

0e eran+es;;;;;;;;;;;;;;;.;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;."*




Table of FiguresFigure ! "mage sho#ing an "N$ %% note having #atermar& at its left side #hich is considera'lyvisi'le #hen note hold under light ..............................................................................8Figure (! #atermar&ing system ................................................................................-9Figure )! *atermar& system in D*+ ........................................................................2-Figure ,! D*+ decomposition #ith t#o levels ............................................................2-!igure *: a< #o6er Image b< WatermarkImage............................................................................................................. 23!igure ,: Watermarking image in ''= 'H= H' and HH bands......... .............. ....2"!igure 7: /atermark e tra+ted rom the ''= 'H= H' and HH bands.................2*!igure : Atta+ks on the /atermarked image on '' band............... ........... ....2,!igure 8: Watermarks re+o6ered rom the '' band a ter atta+ks....................27

!igure -9: Watermark insertion Pro+ess......................................................... 39!igure --: a< Host Image b< Watermark Image....................39!igure -2: Watermarked image /ithout atta+ks and /ith di>erent type oatta+ks................................................................................................ ........... 3-!igure -3: ( tra+ted /atermark a ter ea+h atta+k...................................... ...32!igure -": Watermark embedding using !!T.................................................. 3*!igure -*: a< #o6er Image b< Watermark Image.............3*!igure -,: Watermarking Images a ter di>erent types o atta+ks....... ..... ..... .3,!igure -7: ( tra+ted /atermark a ter di>erent types o atta+ks....... .............37!igure - : insertion and retrie6al o /atermark.................................... .........38

Digital Image Watermarking Page "



ACKNOWLEDGEMENT

ur heart pulsates #ith the thrill for tendering gratitude to those persons #ho helped us in

completion of the project.

+he most pleasant point of presenting a thesis is the opportunity to than& those #ho havecontri'uted to it. Unfortunately/ the list of e0pressions of than& no matter ho# e0tensive is al#aysincomplete and inade1uate. "ndeed this page of ac&no#ledgment shall never 'e a'le to touch thehori2on of generosity of those #ho tendered their help to us.

First and foremost/ #e #ould li&e to e0press our gratitude and inde'tedness to Dr.Allam 3ousa/for his &indness in allo#ing us for introducing the present topic and for his inspiring guidance/constructive criticism and valua'le suggestion throughout this project #or&. *e are sincerelythan&ful to him for his a'le guidance and pain ta&ing effort in improving our understanding of this project. *e are also grateful to everyone taught us in the Department of Electrical

Engineering.An assem'lage of this nature could never have 'een attempted #ithout reference to andinspiration from the #or&s of others #hose details are mentioned in reference section. #eac&no#ledge our inde'tedness to all of them.

4ast 'ut not least/ our sincere than&s to all our friends and our family #ho have patientlye0tended all sorts of help for accomplishing this underta&ing.

Digital Image Watermarking Page *



List of A ron!"s

Acronym Description

D5+ Discrete 5osine +ransformationD*+ Discrete *avelet +ransformationFF+ Fast Fourier +ransformation6PEG 6oint Photographic E0pert Group7N$ 7ignal-to-noise $atio"D5+ "nverse Discrete 5osine +ransform"FF+ "nverse Fast Fourier +ransformation"D*+ "nverse Discrete *avelet +ransformation7$ 7imilarity $atioQF Quality Factor

List of #!"bols

7ym'ol Description

α Em'edding factor or scaling factor

I 5over image 8host image9

W *atermar& image

I w *atermar&ed image

Digital Image Watermarking Page ,



Abstra+t+oday:s #orld is digital #orld. No#adays/ in every field there is enormous use of digital contents."nformation handled on internet and multimedia net#or& system is in digital form. +he copyingof digital content #ithout 1uality loss is not so difficult. Due to this/ there are more chances of

copying of such digital information. 7o/ there is great need of prohi'iting such illegal copyrightof digital media. Digital #atermar&ing 8D*39 is the po#erful solution to this pro'lem. Digital#atermar&ing is nothing 'ut the technology in #hich there is em'edding of various informationin digital content #hich #e have to protect from illegal copying. +his em'edded information to

protect the data is em'edded as #atermar&. ;eyond the copyright protection/ Digital#atermar&ing is having some other applications as fingerprinting/ o#ner identification etc.Digital #ater-mar&s are of different types as ro'ust/ fragile/ visi'le and invisi'le .Application isdepending upon these #atermar&s classifications. +here are some re1uirements of digital#atermar&s as integrity/ ro'ustness and comple0ity.

"n digital #atermar&ing/ a #atermar& is em'edded into a cover image in such a #ay that theresulting #atermar&ed signal is ro'ust to certain distortion caused 'y either standard data

processing in a friendly environment or malicious attac&s in an unfriendly environment. +his project presents a digital image #atermar&ing 'ased on t#o dimensional discrete #avelettransform 8D*+(9/ t#o dimensional discrete cosines transform 8D5+(9 and t#o dimensional fastFourier transform 8FF+(9. 7ignal to noise ratio 87N$9 and similarity ratio 87$9 are computed tomeasure image 1uality for each transform.




#hapter -

Introdu+tion

Digital Image Watermarking Page



Introdu+tion*e are living in the era of information #here 'illions of 'its of data is created in every fraction of a second and #ith the advent of internet/ creation and delivery of digital data 8images/ video andaudio files/ digital repositories and li'raries/ #e' pu'lishing9 has gro#n many fold. 7ince

copying a digital data is very easy and fast too so/ issues li&e/ protection of rights of the contentand proving o#nership/ arises. Digital #atermar&ing came as a techni1ue and a tool to overcomeshortcomings of current copyright la#s for digital data. +he specialty of #atermar& is that itremains intact to the cover #or& even if it is copied. 7o to prove o#nership or copyrights of data#atermar& is e0tracted and tested. "t is very difficult for counterfeiters to remove or alter #atermar&. As such the real o#ner can al#ays have his data safe and secure. ur aim #as tostudy different #atermar&ing techni1ues and implement the one #hich is most resistant to alltypes of attac&/ scalar or geometric. 5ounterfeiters try to degrade the 1uality of #atermar&edimage 'y attac&ing an image 8generally attac&s are median and Gaussian filter/ scaling/compression and rotation of #atermar&ed image9.;y attac&ing #atermar&ed image it 'ecomevery difficult to recover #atermar& 'ac& from the #atermar&ed image and even if it e0tractedone may no longer use it to prove the o#nership and copyrights. 7o our main idea #as to findsuch regions/ also &no#n as patches/ in an image #hich are very sta'le and resistant to attac&s.+he report is divided mainly in , chapters *avelet "mage *atermar&ing 8chapter(9/ D5+ "mage#atermar&ing 8chapter)9/ FF+ "mage #atermar&ing 8chapter,9/ and conclusions.

+his chapter gives full insight of digital #atermar&ing/ its history/ re1uirements/ application and possi'le attac&s. +he first su'heading tells ho#/ #ith information revolution/ the need to havesome techni1ue to prevent piracy and illegal copying of data arises. +his need give rise to a ne#techni1ue/ &no#n as Digital *atermar&ing. *hile proposing any algorithm some parameters areneeded to &eep in mind on #hich the proposed algorithm must 'e consistent. +hese parameters

are discussed in follo#ing section. Follo#ing sections are dedicated to #atermar&ing applicationand attac&s. A lot of #or& is going on for ma&ing #atermar&ing techni1ues immune to#ardsattac& to retain the originality of #atermar& and assuring successful e0traction of #atermar& #ithlo# error pro'a'ilities so to sort out disputes/ if any/ over copyrights or o#nership.




&6er6ie/<old an $s %% note up or your offer letter up to light. *hat you #ill see is a picture of 3ahatmaGandhi or company:s logo respectively. +his is #hat is &no#n as a #atermar& mainly used to

prove the o#nership 8in case of offer letter/ #atermar& prove that the document is of facial

document of company meant for official #or&9 or authenticity 8in case of $s %%/ #atermar& ruleout the forgery and authenticate the piece of paper of its #orth9.+he #atermar& on the $s %%8Figure 9/ just li&e most paper #atermar&s today/ has t#o properties. First/ the #atermar& ishidden from vie# during normal use/ only 'ecoming visi'le as a result of a special vie#ing

process 8in this case/ holding the 'ill up to the light9. 7econd/ the #atermar& carries informationa'out the o'ject in #hich it is hidden 8in this case/ the #atermar& indicates the authenticity of the

'ill9 = >.

Figure 1: Image showing an INR 100 note having watermark at its left side which isconsiderably visible when note hold under light

+hus/ #atermar&ing is defined as/ “ the process of possibly irreversibly embedding informationinto a digital signal. The signal may be audio, pictures or video”.

Digital Image Watermarking Page -9



Figure 2: watermarking system

+he components of a #atermar& em'edding?detection?e0traction system are sho#n in Figure(.+he em'edded data can 'e detected in/ or e0tracted from/ a multimedia element in anapplication.

$istor! of %ater"ar&ingAlthough the art of paperma&ing #as invented in 5hina over one thousand years earlier/ paper #atermar&s did not appear until a'out (@(/ in "taly. +he mar&s #ere made 'y adding thin #ire

patterns to the paper molds. +he paper #ould 'e slightly thinner #here the #ire #as and hencemore transparent. +he meaning and purpose of the earliest #atermar&s are uncertain. +hey mayhave 'een used for practical functions such as identifying the molds on #hich sheets of papers#ere made/ or as trademar&s to identify the paper ma&er. n the other hand/ they may haverepresented mystical signs/ or might simply have servedasdecoration. ;y the eighteenth century/ #atermar&s on paper made in Europe andAmerica had

'ecome more clearly utilitarian. +hey #ere used as trademar&s/ +o record the date the paper #as manufactured/ and to indicate the si2es of original sheets. "t#as alsoa'out this time that #atermar&s 'egan to 'e used as anticounterfeiting measures on moneyand other documents. +he term #atermar& seems to have 'een coined near the end of the eighteenth century and may have 'een derived from the German term #as sermar&e 8though itcould also 'e that the German #ord is derived from the English9. +he term is actually amisnomer/ in that #ater is not especially important in the creation of the mar&. "t #as pro'a'lygiven 'ecause the mar&s resem'le the effects of #ater on paper. A'out the time the term#atermar& #as coined/ counterfeiters 'egan developing methods of forging #atermar&s used to

protect paper money. 5ounterfeiting prompted advances in #atermar&ing technology. *illiam5ongreve/ an Englishman/ invented a techni1ue for ma&ing color #atermar&s 'y inserting dyedmaterial into the middle of the paper during paperma&ing. +he resulting mar&s musthave 'een e0tremely difficult to forge/ 'ecause the ;an& of England itself declined to use them onthe grounds that they #ere too difficult to ma&e. A more practical technology #as invented 'yanotherEnglishman/*illiam<enry7mith.+hisreplacedthe fine #ire patterns used to ma&e earlier mar&s #ith a sort of shallo# relief sculpture/ pressed into the paper mold. +he resulting variationon the surface of the mold produced 'eautiful #atermar&s #ith varying shades of gray. +his is the

'asic techni1ue used today for the face of President 6ac&son on the (% 'ill. Four hundred yearslater/ in BC,/ Emil <em'roo&e of the 3u2a& 5orporation filed a patent for #atermar&ingmusical *or&s. An identification code #as inserted in music 'y intermittently applying a narro#notch filter centered at &<2. +he a'sence of energy at this fre1uency indicated that the notch

Digital Image Watermarking Page --



filter had 'een applied and the duration of the a'sence used to code either a dot or a dash. +heidentification signal used 3orse code. "t is difficult to determine #hen digital #atermar&ing #asfirst discussed. "n B B/ 72epans&i descri'ed a machine-detecta'le pattern that could 'e placed ondocuments for anti-counterfeiting purposes. Nine years later/ <olt descri'ed a methodfor em'edding an identification code in an audio signal. <o#ever/ it #as omatsu and to minaga/in B@@/ #hich appear to have first used the term digital #atermar&. 7till/ it #as pro'a'ly notuntil the early BB%s that the term digital #atermar&ing really came into vogue. A'out BBC/

interest in digital #atermar&ing 'egan to mushroom. "n addition/ a'out this time/ severalorgani2ations 'egan considering #atermar&ing technology for inclusion in various standards. +he5opy Protection +echnical *or&ing Group 85P+*G9 tested #atermar&ing systems for protectionof video on DHD dis&s. +he 7ecure Digital 3usic "nitiative 87D3"9 made #atermar&ing a centralcomponent of their system for protecting music. +#o projects sponsored 'y the European Union/H"HA and +alisman/ tested #atermar&ing for 'roadcast monitoring. +he "nternational

rgani2ation for 7tandardi2ation 8"7 9 too& an interest in the technology in the conte0tof designing advanced 3PEG standards. "n the late BB%s several companies #ere esta'lished tomar&et #atermar&ing products. 3ore recently/ a num'er of companies have used #atermar&ingtechnologies for a variety of applications = >.

'e(uire"ents for %ater"ar&ing algorit)"s*A #atermar&ing algorithm should 'e consistent over follo#ing properties and parameters!

• +ransparency! +he most fundamental re1uirement for any *atermar&ing method shall 'esuch that it is transparent to the end user. +he #atermar&ed content should 'e consuma'leat the intended user device #ithout giving annoyance to the user. *atermar& only sho#sup at the #atermar&-detector device.

• Se+urity: Watermark in ormation shall only be a++essible to theauthori?ed parties. &nly authori?ed parties shall be able to alter theWatermark +ontent. (n+ryption +an be used to pre6ent unauthori?eda++ess o the /atermarked data

• (ase o embedding and retrie6al: Ideally= Watermarking on digitalmedia should be possible to be per ormed @on the yB. The+omputation need or the sele+ted algorithm should be minimum.

• 0obustness: Watermarking must be robust enough to /ithstand allkinds or signal pro+essing operations= @atta+ksB or unauthori?eda++ess. Any attempt= /hether intentional or not= that has a potential toalter the data +ontent is +onsidered as an atta+k. 0obustness againstatta+k is a key re1uirement or Watermarking and the su++ess o thiste+hnology or +opyright prote+tion depends on this.

• (>e+t on band/idth: Watermarking should be done in su+h a /ay thatit doesnCt in+rease the band/idth re1uired or transmission. I Watermarking be+omes a burden or the a6ailable band/idth= themethod /ill be reje+ted.

• Interoperability: Digitally /atermarked +ontent shall still beinteroperable so that it +an be seamlessly a++essed through




heterogeneous net/orks and +an be played on 6arious plays outde6i+es that may be /atermark a/are or una/are.

+",ortan e of Digital Water"ar&ing+he sudden increase in #atermar&ing interest is most li&ely due to the increase in concern over copyright protection of content. +he "nternet had 'ecome user friendly #ith the introduction of 3arc Andreessen:s 3osaic #e' 'ro#ser in Novem'er BB)/ and it 1uic&ly 'ecame clear that

people #anted to do#nload pictures/ music/ and videos. +he "nternet is an e0cellent distri'utionsystem for digital media 'ecause it is ine0pensive/ eliminates #arehousing and stoc&/ anddelivery is almost instantaneous. <o#ever/ content o#ners 8especially large <olly#ood studiosand music la'els9 also see a high ris& of piracy. +his ris& of piracy is e0acer'ated 'y the

proliferation of high-capacity digital recording devices. *hen the only #ay the averagecustomer could record a song or a movie #as on analog tape/ pirated copies #ere usually of a lo#er 1ualitythan the originals/ and the 1uality of second-generation pirated copies 8i.e./ copies of a copy9 #asgenerally very poor. <o#ever/ #ith digital recording devices/ songs and movies can 'e recorded#ith little/ if any/ degradation in 1uality. Using these recording devices and using the "nternet for

distri'ution/ #ould-'e pirates can easily record and distri'ute copyright protected material #ithout appropriate compensation 'eing paid to the actual copyright o#ners.+hus/ content o#ners are eagerly see&ing technologies that promise to protect their rights. +hefirst technology content o#ners turn to is cryptography. 5ryptography is pro'a'ly the mostcommon method of protecting digital content. "t is certainly one of the 'est developed as ascience. +he content is encrypted prior to delivery/ and a decryption &ey is provided only to those#ho have purchased legitimate copies of the content. +he encrypted file can then 'e madeavaila'le via the "nternet/ 'ut #ould 'e useless to a pirate #ithout an appropriate &ey.Unfortunately/ encryption cannot help the seller monitor ho# a legitimate customer handles thecontent after decryption. A pirate can actually purchasetheproduct/ use the decryption &ey to o'tain an unprotected copy of the content/ and thenproceedto distri'ute illegal copies. "n other #ords/ cryptography can protect content intransit/ 'ut once decrypted/ the content has no further protection. +hus/ there is a strong needfor an alternative or complement to cryptography! a technology that can protect content even after it is decrypted.*atermar&ing has the potential to fulfill this need 'ecause it places information #ithin thecontent #here it is never removed during normal usage. Decryption/ re encryption/ compression/digital-to-analog conversion/ and file format changes a #atermar& can 'e designed to survive allof these processes. *atermar&ing has 'een considered for many copy prevention and copyright

protection applications. "n copy prevention/ the #atermar& may'e used to inform soft#areor hard#are devices that copying should 'e restricted. "n copyright protection applications/the #atermar& may 'e used to identify the copyright holder and ensure proper payment of

royalties. Although copy prevention and copyright protection have 'een major driving forces 'ehind research in the #atermar&ing field/ there is a num'er of other applications for #hich#atermar&ing has 'een used or suggested. +hese include 'roadcast monitoring/ transactiontrac&ing/ authentication 8#ith direct analogy to our $s %% e0ample9/ copy control/ and devicecontrol = >.




Ai"sAn effective authentication scheme should have the follo#ing desira'le features!

. +o 'e a'le to determine #hether an image has 'een altered or not.(. +o 'e a'le to locate any alteration made on the image.). +o 'e a'le to integrate authentication data #ith host image rather than as a separate data

file.,. +he em'edded authentication data 'e invisi'le under normal vie#ing conditions.C. +o allo# the #atermar&ed image 'e stored in lossy- compression format =)>.

Classi ation of .igital %ater"ar& 7ome of the important types of #atermar&ing 'ased on different #atermar&s are given 'elo#!

/isible %ater"ar&sHisi'le #atermar&s are an e0tension of the concept of logos. 7uch #atermar&s are applica'le toimages only. +hese logos are inlaid into the image 'ut they are transparent. 7uch #atermar&scannot 'e removed 'y cropping the center part of the image. Further/ such #atermar&s are

protected against such as statistical analysis.+he dra#'ac&s of visi'le #atermar&s are degrading the 1uality of image and detection 'y visualmeans only. +hus/ it is not possi'le to detect them 'y dedicated programs or devices. 7uch#atermar&s have applications in maps/ graphics and soft#are user interface.

+n isible %ater"ar& invisi'le #atermar& is hidden in the content. "t can 'e detected 'y an authori2ed agency only.7uch #atermar&s are used for content and ?or author authentication and for detectingunauthori2ed copier.

Robust Watermark

Em'edded invisi'le #atermar&s.

$esist to image processing or attac&s.

Used for copyright protection or to verify the o#nership.

Fragile Watermark

Fragile #atermar&s are those #atermar&s #hich can 'e easily destroyed 'y any attempt totamper #ith them. Fragile #atermar&s are destroyed 'y data manipulation. "n the follo#ing

Digital Image Watermarking Page -"



figure an e0ample of fragile #atermar&ing the first one represent the original image/ thesecond is the modified image and the third the detected modification.

emi Fragile Watermark

7ensitive to signal modification.

Feature of 'oth ro'ust I Fragile #atermar&.

Provides data authentication.

;esides #atermar& ro'ustness/ #atermar& can also categori2ed into visi'le and invisi'le types/visi'le #atermar&s are percepti'le to a vie#er. n the other hand/ invisi'le #atermar&s areimpercepti'le and don:t change the visual of the images. "n our project/ #e are interested ininvisi'le #atermar&s 'ecause they have a #ider range of applications compared to visi'le#atermar&s=,>.

A,,li ations of .igital %ater"ar&ing

Digital %ater"ar&ing te )nolog! for rig)ts "anage"entne of the traditional applications of the #atermar& is copyright protection. +he primary reason

for using #atermar&s is to identify the o#ner of the content 'y an invisi'le hidden mar& that isimprinted into the image. "n many cases/ the #atermar& is used in addition to the contentencryption/ #here the encryption provides the secure distri'ution method from digital#atermar&ing. the content o#ners to the receivers/ and the #atermar& offers the content o#ners

the opportunity to trace the contents and detect the unauthori2ed use or duplications. *ithout#atermar&ing/ there is no #ay to e0tend the control of the content o#ner once the content leavesthe protected digital domain and is released to the user. Digital #atermar& is used to e0tend the

protection and provide the opportunities for the content o#ners to protect the rights and properties of the electronic distri'uted contents. +he signature of the o#ner/ content "D and usagelimitation can 'e imprinted into the contents/ and stay #ith the contents as far as it travels. +hismechanism e0tends the opportunity of protecting the contents after the release of the contents tothe open environment. +he major technical re1uirements for this application are as follo#s!

• +he #atermar& does not incur visi'le 8or audi'le9 artifacts to the ordinary users.• +he #atermar& is independent of the data format.• +he information carried 'y the #atermar& is ro'ust to content manipulations/

compression/ and so on.• +he #atermar& can 'e detected #ithout the un #atermar&ed original content.• +he #atermar& can 'e identified 'y some &ind of &eys that are used to identify large

num'er of individual contents uni1uely.

Digital watermarking technology for authentication and tamper proofingAnother application of digital #atermar& is contents authentication and tamper proofing. +heo'jective is not to protect the contents from 'eing copied or stolen/ 'ut is to provide a method to

Digital Image Watermarking Page -*



authenticate the image and assure the integrity of the image. 7ince lo#-end digital camera arrivedto the consumer mar&et/ it rapidly e0panded to a num'er of industrial applications as #ell/

'ecause the use of a digital image is far more cost effective and can also save time and cost for the Developing? Printing?E0posing 8DPE9 compared to the traditional chemical photos. <o#ever/there are some critical issues for some particular applications/ #here the photos are used asevidence or the material for some &ind of 'usiness judgment. For instance/ automo'ile insurancecompanies sometimes use photos of the damaged car sent 'y the repair shop to estimate the repair

cost. A shift to digital photos #ill save a great amount of time and money for these &inds of processes. <o#ever/ the digital photos might 'e altered to e0aggerate damage/ or even made upfrom nothing/ since the modification of the digital image is getting much easier #ith someadvanced photo-retouching tools 'e availa'le. +his could result in large amounts of e0tra

payment for the insurance company/ or more seriously/ undermine the credi'ility of the insurancecompany itself. A type of digital #atermar&/ called tamper-detect #atermar&/ might resolve this

pro'lem/ and provide a secure environment for the evidence photos. +he #ay to reali2e thisfeature is to em'ed a layer of the authentication signature into the su'ject digital image using adigital #atermar&. +his additional layer of #atermar& is used as a sensor to detect thealteration. ur recent implementation can even detect the location of the alteration from thealtered image itself. +hrough a joint study #ith a major 6apanese insurance company/ #econfirmed the technical feasi'ility of the technology for the a'ove-mentioned industrial

applications. +he technical re1uirements for this application are as follo#s!• "nvisi'le to the ordinary users.• Applica'le to compressed image format 8most digital cameras use 6PEG compati'le

format9.• 7ensitive to content manipulations/ compression/ and so on.

/isible re ersible %ater"ar&ing for ele troni .istributionUnli&e other digital #atermar&ing technologies descri'ed a'ove/ the visi'le reversi'le #atermar& is visi'le. "t is availa'le as a commercial product . +his uni1ue form of #atermar&ing technology

'y ";3 allo#s the content o#ners to em'ed a visi'le shape or logo mar& such as company:s logoon top of the image. +he mar& is removed 8the #atermar& is reversed9 only #ith the applicationof an appropriate decryption &ey and #atermar& remover soft#are. +his mar& is applied 'ymodifying the Discrete 5osine +ransformation 8D5+9 coefficients of the 6PEG compressed imagefollo#ing certain pre-defined rule and visual effect analysis result to ma&e it half transparent/ 'utnot totally destructive. +he &ey/ #ith the mar& removal program/ #ill 'e used to remove the mar& from the image. +he removal of the visi'le mar& may 'e tied up #ith the em'edding of another invisi'le mar& for the trac&ing purpose. *ith this visi'le #atermar& on the image/ the content

'ecomes self-protective/ and content o#ners can distri'ute the entire image as a sample to variousopen media or to the "nternet. *hen a user #ants to use a clean copy of the image/ all he?sheneeds to 'e is to re1uest a decryption &ey and pay some fee for it. +his #ill reduce the securityris& and the amount of the data transmission per each 'uy?sell transaction=C>.

Water"ar&ing as Co""uni ation #!ste"

*atermar&ing system can 'e vie#ed as some form of communication. +he payloadmessage P / encoded as a #atermar& W / is modulated and transmitted across acommunication channel to the #atermar& detector. "n this model/ the cover #or& represents a communication channel and therefore it can 'e vie#ed as one source of noise. +he other source of noise is a distortion caused 'y normal signal processing and

Digital Image Watermarking Page -,



attac&s. 3odeling #atermar&ing as communication is important 'ecause it ma&es it possi'le to apply various communication system techni1ues/ such as modulation/ error correction/ coding/ spread spectrum communication/ matched filtering/ andcommunication #ith side information/ to #atermar&ing. +hose techni1ues could 'e usedto help design &ey 'uilding 'loc&s of a #atermar&ing system #hich deal #ith thefollo#ing!

• <o# to em'ed and detect one 'it.• *hat processing?em'edding domain to use.• <o# to use side information to ensure impercepti'ility.• <o# to use modulation and multiple0ing techni1ues to em'ed multiple 'its.• <o# to enhance ro'ustness and security/ #here ro'ustness can 'e defined as a#atermar& resistance to normal signal processing/ and security can 'e defined as a#atermar& resistance to intentional attac&s =J>.

D+#TO'+ON# AND ATTACK#First of all/ #e have to distinguish t#o reasons or purposes for an attac& against a #atermar& image!K <ostile or malicious attac&s/ #hich are an attempt to #ea&en/ remove or alter the #atermar&/andK 5oincidental attac&s/ #hich can occur during common image processing and are not aimed attampering #ith the #atermar&. 4ossy image compression is considered the most common form of attac& a #atermar&ing scheme has to #ithstand. +he harsh term attac& can 'e easily justified!an efficient image compression has to suppress or discard perceptually irrelevant information theinvisi'le #atermar&. A #ide range of attac&s has 'een descri'ed in the literature . +he follo#ingfour large categories of attac&s can 'e invo&ed to penetrate a #atermar&ing system!

K $emoval attac&sK Geometrical attac&sK 5ryptographic attac&sK Protocol attac&s

'e"o al atta &sRemoval !sim"le# attacks attempt to separate and remove the #atermar&. "f some'ody tries toremove the #atermar& from the data/ this is called a removal attac&. +he means employed mostfre1uently are filter models ta&en from statistical signal theory. Denoising the mar&ed imagethrough median or high-pass filtering as #ell as nonlinear truncation or spatial #atermar&

prediction are methods considered very li&ely to succeed. +he goal is to add distortion to the hostimage in order to render the #atermar& undetecta'le or unreada'le =,>. +he attac& is successful if the #atermar& cannot 'e detected anymore/ 'ut the image is still intelligi'le and can 'e used for a

particular determined purpose. 3any such attac& operations have 'een proposed!

K 4ossy image compression 86PEG/ 6PEG (%%%9K Addition of Gaussian noiseK DenoisingK FilteringK 3edian filtering and 'lurringK 7ignal enhancement 8sharpening/ contrast enhancement9




$om"ression ! this is generally an unintentional attac&/ #hich appears very often in multimediaapplications. Practically all images currently 'eing distri'uted via "nternet have 'een compressed.the #atermar& is re1uired to resist different levels of compression/ it is usually advisa'le to

perform the #atermar& em'edding in the same domain #here the compression ta&es place. For instance/ the Discrete 5osine +ransform 8D5+9 domain image #atermar&ing is more ro'ust to6oint Photograph E0pert Group 86PEG9 compression than the spatial-domain #atermar&ing. Also/

the Discrete *avelet Domain 8D*+9 domain #atermar&ing is ro'ust to 6PEG (%%% compression.

%dditive noise ! a random signal #ith a given distri'ution 8e.g. Gaussian/ uniform/ Poisson/;ernoulli9 is added to the image unintentionally. "n certain applications the additive noise mayoriginate from Digital-to-Analog 8D?A9 and A?D converters/ or as a conse1uence of transmissionerrors. <o#ever/ an attac&er may introduce perceptually shaped noise 8image-dependent mas&9#ith the ma0imum unnoticea'le po#er. +his #ill typically force to increase the threshold at#hich the correlation detector operates.

&enoising e'"lores the idea that a #atermar& is an additive noise 8#hich can 'e modeledstatistically9 relative to the original image. +hese attac&s include! local median/ midpoint/trimmed mean filtering/ *iener filtering/ as #ell as hard and soft thresholding.

Filtering attacks are linear filtering! high-pass/ lo# pass/ Gaussian and sharpening filtering/ etc.4o#-pass filtering/ for instance doesn:t introduce considera'le degradation in #atermar&edimages/ 'ut can dramatically affect the performance since spread-spectrum-li&e #atermar&s havenon negligi'le high-fre1uency spectral contents. +o design a #atermar& ro'ust to a &no#n groupof filters that might 'e applied to the #atermar&ed image/ the #atermar& message should 'edesigned in such a #ay to have most of its energy in the fre1uencies #hich filters change theleast.

tatistical averaging ! the aim of these attac&s is retrieving the host image and?or #atermar& 'ystatistical analysis of multiple mar&ed data sets. An attac&er may try to estimate the #atermar& and then to un#atermar& the o'ject 'y su'tracting the estimation. +his is dangerous if the

#atermar& doesn:t depend su'stantially on data. +his is a good reason for using perceptual mas&sto create a #atermar&. "n this group of attac&s 'elong the averaging and collusion attac&s.Averaging attac& consists of averaging many instances of a given data set each time mar&ed #itha different #atermar&. "n this #ay an estimate of the host data is computed and each of the#atermar&s is #ea&ened. 5ollusion attac& consists of averaging different host data containing thesame #atermar&. +he resulting signal may serve as a good estimate of the #atermar&/ #hich can

'e used to remove it from the #atermar&ed data.

Geo"etri al atta &s+hese attac&s are not aimed at removing the #atermar&/ 'ut try to either destroy it or disa'le itsdetection. +hey attempt to 'rea& the correlation detection 'et#een the e0tracted and the original#atermar& se1uence/ #here the image is su'jected to translation/ rotation/ scaling and?or

cropping. +his can 'e accomplished 'y shuffing the pi0els. +he values of corresponding pi0elsin the attac&ed and the original image are the same. <o#ever/ their location has changed. +heseattac&s can 'e su'divided into attac&s applying general affine transformations and attac&s 'asedon projective transformation. 5ropping is a very common attac& since in many cases the attac&er is interested in a small portion of the #atermar&ed o'ject/ such as parts of a certain picture or frames of video se1uence. *ith this in mind/ in order to survive/ the #atermar& needs to 'espread over the dimensions #here this attac& ta&es place.

Digital Image Watermarking Page -



(osaic attack) +his point is emphasi2ed 'y a presentation attac&/ #hich is of 1uite generalapplica'ility and #hich possesses the initially remar&a'le property that a mar&ed image can 'eunmar&ed and yet still rendered pi0el for pi0el in e0actly the same #ay as the mar&ed image 'y astandard 'ro#ser. +he attac& #as motivated 'y a fielded automatic system for copyright piracydetection/ consisting of a #atermar&ing scheme plus a #e' cra#ler that do#nloads pictures fromthe net and chec&s #hether they contain a #atermar&. "t consists of chopping an image up into anum'er of smaller su' images/ #hich are em'edded in a suita'le se1uence in a #e' page.

5ommon #e' 'ro#sers render ju0taposed su' images stuc& together/ so they appear identical tothe original image/ #hich is sho#n in Fig. ). +his attac& appears to 'e 1uite generalL all mar&ingschemes re1uire the mar&ed image to have some minimal si2e 8one cannot hide a meaningfulmar& in just one pi0el9. +hus 'y splitting an image into sufficiently small pieces/ the mar& detector #ill 'e confused. +he 'est that one can hope for is that the minimal si2e could 'e 1uitesmall and the method might therefore not 'e very practical.

Cr!,togra,)i atta &s5ryptographic attac&s aim at crac&ing the security methods in #atermar&ing schemes and thusfinding a #ay to remove the em'edded #atermar& information or to em'ed misleading

#atermar&s. ne such techni1ue is 'rute-force search for the em'edded secret information.Practically/ application of these attac&s is restricted due to their high computational comple0ity.+hey cover/ for e0ample/ direct attac&s to find the secret &ey or attac&s called collusion attac&s.5ryptographic attac&s are very similar to the attac&s used in cryptography. +here are the 'ruteforce attac&s/ #hich aim at finding secret information through an e0haustive search. 7ince many#atermar&ing schemes use a secret &ey/ it is very important to use &eys #ith a secure length.Another attac& in this category is so-called racle attac& #hich can 'e used to create a non-#atermar&ed image #hen a #atermar& detector device is availa'le.

roto ol atta &sProtocol attac&s neither aim at destroying the em'edded information nor at disa'ling thedetection of the em'edded information 8deactivation of the #atermar&9. $ather/ they ta&e

advantage of semantic deficits of the #atermar&:s implementation. +he protocol attac&s aim atattracting the concept of the #atermar&ing application. +he first protocol attac& #as proposed 'y5raveret al. +hey introduced the frame#or& of inverti'le #atermar& and sho#ed that for copyright protection applications #atermar&s need to 'e non-inverti'le. +he idea of inversionconsists of the fact that an attac&er #ho has a copy of the stego-data can claim that the datacontains also the attac&er:s #atermar& 'y su'tracting his o#n #atermar&. +his can create asituation of am'iguity #ith respect to the real o#nership of the data. +he re1uirement of non-inverta'ility on the #atermar&ing technology implies that it should not 'e possi'le to e0tract a#atermar& from non-#atermar&ed image. As a solution to this pro'lem/ the authors proposed toma&e #atermar&s signal-dependent 'y using a one-#ay function. 5onse1uently/ a #atermar& must not 'e inverti'le or to 'e copied. A copy attac&/ for e0ample/ #ould aim at copying a#atermar& from one image into another #ithout &no#ledge of the secret &ey. "t also 'elongs to

the group of the protocol attac&s. "n this case/ the goal is not to destroy the #atermar& or impair its detection/ 'ut to estimate a #atermar& from #atermar&ed data and copy it to some other data/called target data = >.

"n our #or& #e use removal attac&s to compare 'et#een the different techni1ues/ #e compressthe #atermar&ing image using 6PEG compressionL also #e add Gaussian noise and salt and

peppers noise to the #atermar&ing image and then #e filtering it using median filter.







*uality Measure"ents

"n order to evaluate the 1uality of #atermar&ed image/ the follo#ing signal-to-noise ratio 87N$9e1uation is used!

SNR=∑i= 1

M

∑ j= 1

N

I 2(i , j )

∑i= 1

M

∑ j= 1

N

[ I (i , j )− I w (i , j)]2

$/

SNRd B= 10∗log 10∑i= 1

M

∑ j= 1

N

I 2

(i , j )

∑i= 1

M

∑ j=1

N

[ I (i , j )− I w(i , j )]2

+he num'er of mismatched data 'et#een the em'edded #atermar& and the e0tracted #atermar& is used to represent the similarity of #atermar&s. +he similarity factor of e0tracted #atermar& andoriginal #atermar& is computed 'y the follo#ing!

SF =∑i= 1

M

∑ j= 1

N

(W (i , j )2∗W ' (i , j)2 )

√∑i= 1

M

∑ j= 1

N

W (i , j )2∗∑

i= 1

N

∑ j= 1

N

W ' (i , j )2

*hereW

andW '

represent the original #atermar& image and the e0tracted #atermar& image/ respectively/ 3 and N represent the image si2e. +he magnitude range of 7F is =%/ >. 7F isnear or e1uals to / the e0tracted #atermar& is more effective e0traction. "n general/ it isconsidered accepta'le that 7F is %. C or a'ove.

Digital Image Watermarking Page 2-



#hapter 2

DWT Image /atermarking




DWT Do"ain Water"ar&ing*avelet transform is a time domain locali2ed analysis method #ith the #indo#:s si2e fi0ed andforms converti'le. +here is 1uite good time differentiated rate in high fre1uency part of signalsD*+ transformed. Also there is 1uite good fre1uency differentiated rate in its lo# fre1uency part."t can distill the information from signal effectively. +he 'asic idea of discrete #avelet transform8D*+9 in image process is to multi-differentiated decompose the image into su'-image of different spatial domain and independent fre1uency district .+hen transform the coefficient of su'-image. After the original image has 'een D*+ transformed/ it is decomposed into ,fre1uency districts #hich is one lo# fre1uency district8449 and three high-fre1uencydistricts84</<4/<<9. "f the information of lo#-fre1uency district is D*+ transformed/ the su'-level fre1uency district information #ill 'e o'tained. +he follo#ing figure represents the#atermar&ing system in D*+ =@>!

Figure +: Watermark system in &W,

"n t#o-dimensional separa'le dyadic D*+/ each level of decomposition produces four 'ands of data/ one corresponding to the lo# pass 'and 8449/ and three other corresponding to hori2ontal8<49/ vertical 84<9/ and diagonal 8<<9 high pass 'ands. +he decomposed image sho#s a coarseappro0imation image in the lo#est resolution lo# pass 'and/ and three detail images in higher

'ands. +he lo# pass 'and can further 'e decomposed to o'tain another level of decomposition.+his process is continued until the desired num'er of levels determined 'y the application isreached =(>.

Figure -: &W, decom"osition with two levels

+he proposed #atermar&ing system is given in the follo#ing process!




.mbedding watermarking

In"ut: 5over image/ #atermar& image.

/rocess:

. using t#o-dimensional separa'le dyadic D*+/ o'tain the first level decomposition of the cover image I .

(. 3odify the D*+ coefficients in the 44 'and!

¿wi , j= ¿i , j +α k wij , i , j= 1 , … , n

). Apply inverse D*+ to o'tain the #atermar&ed cover "mage/ Iw.

ut"ut: *atermar&ed image.

.'tracting watermarking

In"ut: *atermar&ed cover image.

/rocess:

. using t#o-dimensional separa'le dyadic D*+/ o'tain the first level decomposition of the

#atermar&ed 8and possi'ly attac&ed9 cover image I w¿

.

(. E0tract the 'inary visual #atermar& from the 44 'and!

w ij=( ¿w, ij − ¿ij)/α

ut"ut: #atermar& image.

#i"ulation results7ince the magnitudes of D*+ coefficients are larger in the lo#est 'and at each level of decomposition/ it is possi'le to use a larger scaling factor for #atermar& em'edding. For theother ) 'ands/ the D*+ coefficients are smaller/ allo#ing a smaller scaling factor to 'e used.+he resulting #atermar&ed image does not have any degradation leading to a loss in itscommercial value. "n the 'elo# e0periments/ #e measured the visual 1uality of #atermar&ed and

attac&ed images using the 7ignal +o-Noise $atio 87N$9/ 7N$ measures are estimates of the1uality of the reconstructed image compared #ith an original image. +he fundamental idea is tocompute the value #hich reflects the 1uality of the reconstructed image. $econstructed image#ith higher metric are judged as having 'etter 1uality.

+he visual 1uality of e0tracted visual #atermar&s is measured 'y the 7imilarity Factor 87F9. +heD*+ #as performed using 3atla' #ith the #avelet filter. +he chosen attac&s #ere 6PEGcompression 8#ith ) 1uality factors9/ also #e measured a compression ratio 85$9 it defined 'ycompression $atioMimage 'ytes?compressed 'ytes.

Digital Image Watermarking Page 2"



For first levels of decomposition/ the proposed #atermar&ing scheme #as tested using si0 typesof attac&s. +he D*+ #as performed using 3atla'. +he chosen attac&s #ere 6PEG compression8#ith ) 1uality factors9/ 'lurring/ adding Gaussian noise/ filtering/ histogram e1uali2ation/intensity adjustment and rotation. +he scaling factor #e use it #ith three different values %.%B/ %.Cand %.@.

+he follo#ing data calculated from run matla' code for D*+ #atermar&ing for different value of 1uality factor and alpha 8gain9.

First Le el De o",ositionFigure C sho#s the (CJ0(CJ gray scale cover image 5ameraman and (@0 (@ visual #atermar& copyright.

Figure * a3 Co er +"age b3

Water"ar& +"age

+he #atermar&ed image in 44/ 4</ <4 and << 'ands are presented respectively in Figure J for different value of scaling factors and different 1uality factors/ and the num'er 'elo# each imagedenotes the 7N$ value.

Figure contains the #atermar&s e0tracted from the four 'ands for each value of alpha and QF.+he num'ers 'elo# the images are the 7F values. According to Figure #e can note that#atermar& em'edding in the 44 'and is most resistant to 6PEG compression than other 'ands.

+he attac&ed images are presented in Figure @ together #ith the tools and parameters used for theattac&s. +he num'er ne0t to the la'el 'elo# each image denotes the 7N$ value. Figure B contains

the #atermar&s e0tracted from the 44 'and for each of the attac&s. +he num'ers ne0t to theimages are the 7F values. According to Figure @ and Figure B/ it is possi'le to note the resistanceof #atermar&ed image for each attac& using either su'jective human evaluation or o'jective 7F.

Digital Image Watermarking Page 2*



S%0 2-.2-93

S%0 2-.7"-"

S%0 -8.89--

S%02-.28,9

S%0 2-.7 ",

S%0 29.8-*

S%02-.*987

S%0 29.2 9"

S%0 22.3**7

S%0 2-.7889

S%02-.78 9

S%0 2-.78 *

EP() ,9 = alpha 9.98 EP() 9 = alpha 9.98 EP() -99 = alpha 9.98

S%0 8.* 98

S%0 7.728

S%0 7. -**

S%0 7. 88*

S%0 8.*8""

S%0 7.7,9*

S%0 7. -9"

S%07.737"

S%0 8.,-2,

S%0 7.77*7

S%0 7.77"7

S%07.7772

EP() ,9 = alpha 9.* EP() 9 = alpha 9.* EP() -99 = alpha 9.*

S%0 7.2 ,9

S%0 ".7 8"

S%0 ".787 S%0

S%0 7.2837

S%0 ". -99

S%0 ". 92 S%0

S%0 7.28"-

S%0 ". 9"-

S%0 ". 9, S%0

Digital Image Watermarking Page 2,



".7 9* 8 ". 9-7 2 ". 9 *

EP() ,9 = alpha 9. EP() 9 = alpha 9. EP() -99 = alpha 9.Figure 4* Water"ar&ing i"age in LL5 L$5 $L an. $$ ban.s

S!9. *2-

S! 9."8-7

S! 9. 7 S! 9.3 --

S! 9. 72 S! 9. ,

S! 9.78"9 S! 9 .89*2

S! 9.888 S! -

S! - S! -

EP() ,9 = alpha 9.98 EP() 9 = alpha 9.98 EP() -99 = alpha 9.98

S! 9.8837 S! 9.7,8

S! 9.7779 S! 9.7 9

S! 9.88"- S! 9.77 *

S! 9.778 S! 9 .7787

S! 9.88"- S! 9.7 "-

S! 9.7 98 S! 9 .7 3,

EP() ,9 = alpha 9.* EP() 9 = alpha 9.* EP() -99 = alpha 9.*




S! 9. 9-, S! 9.7*92

S! 9.7*"" S! 9 .7"""

S! 9. 939 S! 9.7*,8

S! 9.7* , S! 9 .7*79

S! 9.788, S! 9.7* 9

S! 9.7,92 S! 9 .7,-

EP() ,9 = alpha 9. EP() 9 = alpha 9. EP() -99 = alpha 9.Figure 6* %ater"ar& e7tra te. fro" t)e LL5 L$5 $L an. $$ ban.s

%it) #F

EP() ,9: 2-.2-93 Intensity Adj.: -".72*- Fluring: -2."* 2

SaltG peppers noise 9.92<:-,.- 39

SaltG peppers noise 9.*<:".2--*

median 4lter: -8.3-8,




)aussian noise : --.38"* 0otating 3* : 9."77* Histogram (1uali?ation:-".287"

Figure 8* Atta &s on t)e %ater"ar&e. i"age on LL ban.

EP() ,9 : 9. *2- Intensity Adj. :9.7,,8 Fluring: 9.7*37

SaltG peppers noise 9.92<: SaltG peppers noise 9.*<: median 4lter: 9.8-23




9.8,23 9.*2-*

)aussian noise : 9.,"-8 0otating 3* : 9.2 92 Histogram (1uali?ation:9.*--

Figure 9* Water"ar&s re o ere. fro" t)e LL ban. after atta &ss)o%ing #F

#hapter 3

D#T Image /atermarking




+ntro.u tion+he discrete cosine transform 8D5+9 represents an image as a sum of sinusoids of varyingmagnitudes and fre1uencies. +he D5+ has special property that most of the visually significantinformation of the image is concentrated in just a fe# coefficients of the D5+. "t:s referred as

Energy compaction Property:.

As D5+ is having good energy compaction property/ many D5+ 'ased Digital image#atermar&ing algorithms are developed. 5ommon pro'lem #ith D5+ #atermar&ing is 'loc&

'ased scaling of #atermar& image changes scaling factors 'loc& 'y 'loc& and results in visualdiscontinuity =B>. "n this chapter/ #e propose a visi'le #atermar&ing techni1ue that modifies theD5+ coefficients of the host image using e1n. 8 9. *e call an em'edding factor #e try differentvalues for it to achieve visi'le #atermar&ing #e find O M % a good value and #e also use O M%.%Bfor invisi'le #atermar&ing. *e have also proposed a modification to ma&e the #atermar& morero'ust.

+N#E'T+ON OF WATE'MA'K Figure C gives the schematic representation of the insertion process. +he steps for #atermar& insertion are discussed 'elo#!

• +he original image " 8to 'e #atermar&ed9 and the #atermar& image * are reading. 8;oththe images may 'e not of e1ual si2e9.

• +he #atermar& image resi2e if necessary to ma&e it si2e the same of host image.• +he D5+ coefficients for host image and #atermar& image are found out.• +he value of em'edding factor defined to 'e suita'le for visi'le #atermar&ing.

Digital Image Watermarking Page 3-



• +he D5+ coefficient of the host image and #atermar& image is modified using thefollo#ing e1uation. +he "D5+ of modified coefficients give the #atermar&ed image.

I wi, j= I i , j +α w ij , i , j= 1 ,…,n

+o e0tract the #atermar& applying the follo#ing e1uation!

w ij=( I w,ij − I ij)/α

Figure 10* Water"ar& insertion ro ess

#i"ulation resultFigure sho#s the C (0C ( gray scale cover image 4ena and C (0C ( #atermar& copyright.




Figure 11* a3 $ost +"age b3 Water"ar&+"age

After running code and achieve desired result five types of attac&s applied to the #atermar&edimage. +he attac&ed images are presented in Figure ( together #ith the tools and parametersused for the attac&s. +he num'er ne0t to the la'el 'elo# each image denotes the 7N$ value.Figure ) contains the #atermar&s e0tracted from the #atermar&ed for each of the attac&s. +henum'ers ne0t to the images are the 7F values. According to Figure ( and Figure )/ it is possi'leto note the resistance of #atermar&ed image for each attac& using either su'jective humanevaluation or o'jective 7F.

EP() 7*: .- "- SaltG peppers noise 9.92<:3-.7992

SaltG peppers noise 9.92<:"".",93

With alpha 9.98




Fluring: -,.-2-9 0otating 3* : 9. 22 )aussian noise 9.92*<:--.-9"*

Figure 12* Water"ar&e. i"age %it) .i:erent t!,es of atta &

EP() 7*: 9.888

SaltG peppers noise 9.92<:9.**--

With alpha -9

SaltG peppers noise 9.92<:9.--89

With alpha 9.98

Digital Image Watermarking Page 3"



Fluring: 9.,-8* 0otating 3* : 9.982* )aussian noise 9.92*<:9.2 *8

Figure 1;* E7tra te. %ater"ar& after ea ) atta &

#hapter "

!!T Image /atermarkingDigital Image Watermarking Page 3*



Digital Image Watermarking Page 3,



Fourier Transfor"

+he Fourier +ransform is an important image processing tool #hich is used to decompose animage into its sine and cosine components. +he output of the transformation represents the imagein the Fourier or fre1uency domain / #hile the input image is the spatial domain e1uivalent. "n theFourier domain image/ each point represents a particular fre1uency contained in the spatial

domain image = %>.

+he Fourier +ransform is used in a #ide range of applications/ such as image analysis/ imagefiltering/ image reconstruction/ image compression and image #atermar&ing.

+N#E'T+ON OF WATE'MA'K Figure , gives the schematic representation of the insertion process. +he steps for #atermar& insertion are discussed 'elo#!

• +he original image " 8to 'e #atermar&ed9 and the #atermar& image * are reading. 8;oth

the images may 'e not of e1ual si2e9.• +he #atermar& image resi2e if necessary to ma&e it si2e the same of host image.• +he FF+ coefficients for host image and #atermar& image are found out.• +he value of em'edding factor defined to 'e suita'le for visi'le #atermar&ing.• +he FF+ coefficient of the host image and #atermar& image is modified using the

follo#ing e1uation. +he "FF+ of modified coefficients give the #atermar&ed image.

I wi, j= I i , j +α w ij , i , j= 1 ,…,n

E7tra te. of %ater"ar& +o e0tract the #atermar& applying the follo#ing e1uation!

w ij=( I w,ij − I ij)/α


http://homepages.inf.ed.ac.uk/rbf/HIPR2/freqdom.htm



http://homepages.inf.ed.ac.uk/rbf/HIPR2/spatdom.htm







Figure 1<* Water"ar& e"be..ing using FFT

#i"ulation resultFigure C sho#s the C (0C ( gray scale cover image 4ena and C (0C ( #atermar& copyright.

Figure 1 * a3 Co er +"age b3 Water"ar&+"age




After running code and achieve desired result five types of attac&s applied to the #atermar&edimage. +he attac&ed images are presented in Figure J together #ith the tools and parametersused for the attac&s. +he num'er ne0t to the la'el 'elo# each image denotes the 7N$ value.Figure contains the #atermar&s e0tracted from the #atermar&ed for each of the attac&s. +henum'ers ne0t to the images are the 7F values. According to Figure J and Figure / it is possi'leto note the resistance of #atermar&ed image for each attac& using either su'jective humanevaluation or o'jective 7F.

EP() 7*: .**3- SaltG peppers noise 9.92<:3-."793

Without atta+ks: "2.-"88

Fluring: 39." "* 0otating 3* : 9. 9- )aussian noise 9.92*<:--.-,2

Figure 14* Water"ar&ing +"ages after .i:erent t!,es of atta &s




EP() 7*: 9.888, SaltG peppers noise 9.92<:9.**",

Without atta+ks: -

Fluring: 9.,-8* 0otating 3* : 9.982* )aussian noise 9.92*<:9.2 -

Figure 16* E7tra te. %ater"ar& after .i:erent t!,es of atta &s

"n the Figure a'ove #e have e0tracted #atermar&s after different type of attac&s applying on the#atermar&ing image/ #e can note that this method ro'ust against 6PEG compression.

Digital Image Watermarking Page "9



Co",arison bet%een DCT an. FFTAs discussed in t#o previous chapters #e can note that the D5+ and FF+ algorithm are the same.+he process doesn:t changeL Figure @ sho# the summary of insertion and retrieval of #atermar&

process #e can easily change the type of the transformer. +he different 'et#een the t#o types #illappear in the results/ +a'le C sho# the results.

+ype of attac& D5+ scheme FF+ scheme

6PEG C .- "- .**3-

7alt I peppers noise 3-.7992 3-."793

Gaussian noise --.-9"* --.-,2

$otating 3* 9. 22 9. 9-

;lurring -,.-2-9 39." "*

Table 1* Co",arison bet%een DCT =FFT for .i:erent t!,es of atta &

From the ta'le a'ove #e can note that the t#o methods have appro0imately/ the same result. +hevalue of 7N$ in the ta'le indicates that FF+ ro'ust to 'lurring attac& more than D5+ 'ut for

other attac&s are the same. For retrieval #atermar& image #e can also compare 'et#een the t#otechni1ues. "n +a'le ( #e compare 'et#een them for different types of attac&s using 7F as visual1uality.

+ype of attac& D5+ scheme FF+ scheme

6PEG C 9.888 9.888,

7alt I peppers noise 9.**-- 9.**",

Gaussian noise 9.2 *8 9.2 -

$otating 3* 9.982* 9.982*

Digital Image Watermarking Page "-



D#T J !!T

D#T J !!T

ID#T J I!!T

K

Watermark image

Host image

0etrie6al

Salt G peppers noise

Watermarking Image

Watermarking image /ith noise

( tra+ted Watermark

;lurring 9.,-8* 9.,-8*

Table 2* o",arison bet%een e7tra te. %ater"ar&s using #F>




#on+lusions"n chapter one #e have general definition of digital image #atermar&ing/ our o#n #or& in#atermar&ing start on chapter t#o using D*+ first #e decompose the host image into four 'ands44/ 4</ <4 and << and #e em'edding the #atermar& in each 'and and #ith different values of

QF and em'edding factor #e note that at QFM %% and alphaM%.%B #e can retrieval the #atermar& image #ith 7FM / Figure J sho# #atermar&ing image in different 'ands and #e use 7N$ tocompare 'et#een them/ Figure sho# e0tracted #atermar& from each 'and also #e use 7F tocompare 'et#een them. Applying different type of attac&s on #atermar&ing image em'edding onthe 44 'and #e record the result in Figure @ and note the effect of each type/ 44 'and morero'ust to 6PEG compression and intensity adjustment.

"n chapter three and four #e discuss #atermar&ing process in t#o fre1uency domain D5+ andFF+ #e notice that the process is the same 'ut #e apply different transformation/ also #e cannote that the t#o method have the same ro'ust for all types of attac& e0cept 'lurring #e can notethat FF+ more ro'ust than D5+.


Figure 18* insertion an. retrie al of %ater"ar&



Appendi"n this section #e #ill sho# our codes for digital image #atermar&ing using different techni1ues

DWT code

Digital Image Watermarking Page ""

% loading cover imageX=imread( 'cameraman.tif' );X=im2double(X);[F1,F2]= wfilters( 'db1' , 'd' );[LL,L , L, ] = dwt2(X, 'db1' , 'd' );!"atermar# ima$eb=imread( 'messa$e%co& ri$ t.bm&' );le el=$ra t res (b);w=im2bw(b,le el);w=double(w);al& a=*.*+;#=w al& a;LL%1=LL-#;

= idwt2(LL%1,L , L, , 'db1' , 'd' );! /torin$ t e ima$e to loss file formats.0&e$=in&ut( ' ualit Factor = ' );

imwrite( , '3 4.0&$' , '0&$' , ' ualit ' , );=imread( '3 4.0&$' );

ims ow(( )); ! /te$o ima$etitle ( 'watermar#ed 5ma$e' );w1= ( L16 L).7al& a ; ! e3tracted t e watermar#le el1=$ra t res (w1);w2=im2bw(w1,le el1);w2=im2double(w2);ims ow((w2));title ( '83trected "atermar#' );!/9: measurement41=double( );snr%num=*;snr%den=*;for i=1 2< for 0=1 2< snr%num=snr%num-(41(i,0) 41(i,0)); snr%den=snr%den-((X(i,0)641(i,0)) (X(i,0)641(i,0))); endendsnr=1* lo$1*(snr%num7snr%den)!/imilarit Factor (/F) >easurementsf%num=*; sf%den=*;a=*; b=*;for i=1 <12

for 0=1 <12 sf%num=sf%num-(w1(i,0) o(i,0)); a=a-(o(i,0) o(i,0)); b=b-(w1(i,0) w1(i,0)); sf%den=s rt(sf%den-a b);

endend sf=(sf%num7sf%den)



DCT Code

Digital Image Watermarking Page "*



FFT Code

Digital Image Watermarking Page ",

I = im2double(imread( 'bb.bm&' ));al& a=1*;X = dct2(5);o=im2double(imread( 'ba.bm&' ));ims ow (o),r=dct2(o);

?2=r al& a;X=X-?2;a = idct2(X);w1=(a65).7al& a;! /torin$ t e ima$e to loss file formats.0&e$

=in&ut(' ualit Factor = ');imwrite(a,'3 4.0&$','0&$',' ualit ', );a=imread('3 4.0&$');

ims ow((a));title ( '"atermar#in$ 5ma$e' );ims ow((w1));title( 'detected 8mbedded "atermar#' );

! !/9: measurement41=double(a);snr%num=*;snr%den=*;for i=1 <12 for 0=1 <12 snr%num=snr%num-(41(i,0) 41(i,0)); snr%den=snr%den-((5(i,0)641(i,0)) (5(i,0)641(i,0))); endendsnr=1* (lo$1*(snr%num7snr%den))!/imilarit Factor (/F) >easurement

sf%num=*;sf%den=*;a=*;b=*;for i=1 <12 for 0=1 <12 sf%num=sf%num-(w1(i,0) o(i,0)); a=a-(o(i,0) o(i,0)); b=b-(w1(i,0) w1(i,0)); sf%den=s rt(sf%den-a b);

end end sf=(sf%num7sf%den)

close all ; clc;5 = im2double(imread( 'bb.bm&' ));ims ow(5);X=fft(5);al& a=1*;o=im2double(imread( 'ba.bm&' ));r=fft(o);?=r. al& a;X=X-?;@=ifft(X);w1= (a65).7al& a;

!/torin$ t e ima$e to loss file formats.0&e$=in&ut( ' ualit Factor = ' );

imwrite(a, '3 4.0&$' , '0&$' , ' ualit ' , );a=imread( '3 4.0&$' ); a=im2double(a); ims ow((a));title ( '"atermar#in$ 5ma$e' );ims ow((w1));title( 'detected 8mbedded "atermar#' ); !/9: measurement41=double(a);snr%num=*;snr%den=*;for i=1 <12 for 0=1 <12 snr%num=snr%num-(41(i,0) 41(i,0)); snr%den=snr%den-((5(i,0)641(i,0)) (5(i,0)641(i,0))); end

endsnr=1* lo$1*(snr%num7snr%den)!/imilarit Factor (/F) >easurement

sf%num=*;sf%den=*;a=*;b=*;for i=1 <12 for 0=1 <12 sf%num=sf%num-(w1(i,0) o(i,0)); a=a-(o(i,0) o(i,0)); b=b-(w1(i,0) w1(i,0));

sf%den=s rt(sf%den-a b); end

end sf=(sf%num7sf%den)



0e eren+esL- . http!??###.scri'd.com?doc?) %( %(J?Project-$eport-on-Digital-*atermar&ing .

=(>. 3in *u ;ede 4iu/ *A+E$3A$ "NG F $ "3AGE AU+<EN+"5A+" N /

Department of Electrical Engineering/ Princeton University/ Princeton.

L3 . http:JJhomepages.6ub.a+.beJNandoomsJresear+h.html

L" . http!??###.alpvision.com?#atermar&ing.html

L* . Edin 3uharemagic and ;or&o Furht/ 7urvey f *atermar&ing +echni1ues AndApplications / Department of 5omputer 7cience and Engineering/ Florida AtlanticUniversity.

L, . Andreja 7am covi c/ 6 an +ur an/ A++A5 7 N D"G"+A4*AHE4E+"3AGE*A+E$3A$ 7 / 6ournal of E4E5+$"5A4 ENG"NEE$"NG.

L7 . Peining +aoa and Ahmet 3. Es&icioglu'/ A ro'ust multiple #atermar&ing scheme in theDiscrete *avelet +ransform domain / +he Graduate 5enter/ +he 5ity University of Ne# Ror&.

=@>. ;aisa 4. Gunjal/ AN HE$H"E* F +$AN7F $3 D 3A"N $ ;U7+ D"G"+A4"3AGE *A+E$3A$ "NG A4G $"+<37 / Department of 5omputer Engineering/Amrutvahini 5ollege of Engineering.

=B>. $. Gon2ales/ $. *oods Digital "mage Processing / Addison-*esley Pu'lishing 5ompany.#ontents

http://www.scribd.com/doc/37021026/Project-Report-on-Digital-Watermarking


http://homepages.vub.ac.be/~andooms/research.html




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Digital Image Watermarking dwt,dct,fft