Digitalwatermarking

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DIGITAL WATERMARKING
BY
OPE SINZU
ESUT/2013/1
A SEMINAR REPORT SUBMITTED TO THE
DEPARTMENT OF COMPUTER SCIENCE
FACULTY OF APPLIED NATURAL SCIENCES
ENUGU STATE UNIVERSITY OF SCIENCE AND TECHNOLOGY,
ENUGU
IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF
BACHELOR OF SCIENCE (BSc)
DEGREE IN COMPUTER SCIENCE
MAY, 2017

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ACKNOWLEDGEMENTS
I wish to thank my seminar supervisor in the person of Mrs Edith Ugwu for her guidance and patience
throughout this seminar report writing, and also the lecturers in computer science department who
are bent on giving us the best in academics. A big thanks goes to my parents they are my fortress and
to the Almighty God the giver of life and wisdom.

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ABSTRACT
Digital watermarking is the technique by which materials are embedded into an object using digital
means basically done for security purposes to avoid copyright and intellectual property theft, this
material explains in depth different techniques of digital watermarking, the tools used for such, real
life applications of digital watermarking, types of digital watermarking and the security challenges
facing digital watermarking in the this age of increasing technological advancement.

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1.0 INTRODUCTION
The advent of the Internet has resulted in many new opportunities for the creation and delivery of
content in digital form. Applications include electronic advertising, realtime video and audio delivery,
digital repositories and libraries, and Web publishing. An important issue that arises in these
applications is the protection of the rights of all participants. It has been recognized for quite some
time that current copyright laws are inadequate for dealing with digital data. This has led to an interest
towards developing new copy deterrence and protection mechanisms. One such effort that has been
attracting increasing interest is based on digital watermarking techniques. Digital watermarking is the
process of embedding information into digital multimedia content such that the information (which
we call the watermark) can later be extracted or detected for a variety of purposes including copy
prevention and control. Digital watermarking has become an active and important area of research,
and development and commercialization of watermarking techniques is being deemed essential to
help address some of the challenges faced by the rapid proliferation of digital content. A digital
watermark can be visible or invisible. A visible watermark typically consists of a conspicuously
visible message or a company logo indicating the ownership of the image. On the other hand, an
invisibly watermarked image appears very similar to the original. The existence of an invisible
watermark can only be determined using an appropriate watermark extraction or detection algorithm.
An invisible watermarking technique, in general, consists of an encoding process and a decoding
process.

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1.1 BACKGROUND
Digital watermarking is the act of hiding a message related to a digital signal (i.e. an image, song,
video) within the signal itself. It is a concept closely related to steganography, in that they both hide
a message inside a digital signal. However, what separates them is their goal. Watermarking tries to
hide a message related to the actual content of the digital signal, while in steganography the digital
signal has no relation to the message, and it is merely used as a cover to hide its existence.
Watermarking has been around for several centuries, in the form of watermarks found initially in
plain paper and subsequently in paper bills. However, the field of digital watermarking was only
developed during the last 15 years and it is now being used for many different applications.
The term “Digital Watermark” was coined by Andrew Tirkel and Charles Osborne in December 1992.
The first successful embedding and extraction of a steganographic spread spectrum watermark was
demonstrated in 1993 by Andrew Tirkel, Charles Osborne and Gerard Rankin.
Watermarks are identification marks produced during the paper making process. The first watermarks
appeared in Italy during the 13th century, but their use rapidly spread across Europe. They were used
as a means to identify the papermaker or the trade guild that manufactured the paper. The marks often
were created by a wire sewn onto the paper mould. Watermarks continue to be used today as
manufacturer’s marks and to prevent forgery.

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1.2 OBJECTIVES OF THE SEMINAR
The important issues this seminar report wishes to address that arise in the study of digital
watermarking techniques are:
i. Capacity: what is the optimum amount of data that can be embedded in a given signal, what
is the optimum way to embed and then later extract this information.
ii. Robustness: How do we embed and retrieve data such that it would survive malicious or
accidental attempts at removal.
iii. Transparency: How do we embed data such that it does not perceptually degrade the
underlying content.
iv. Security: How do we determine that the information embedded has not been tampered,
forged or even removed.

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1.3 SIGNIFICANCE OF THE SEMINAR
The significance of this seminar report is that it discusses different areas of digital
watermarking
i. Information and Communication Theory
ii. Decision and Detection Theory
iii. Signal Processing
iv. Cryptography and Cryptographic Protocols

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1.4 SCOPE OF THE SEMINAR
This material covers limited aspect of digital watermarking for the purpose of this study, digital
watermarking is vast to cover in this material only the fraction necessary to study was culled.

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1.5 CONSTRAINTS AND LIMITATIONS
The constraints of digital watermarking is mostly the issue of security, security in the sense that how
can one determine that the information embedded has not been tampered, forged or even removed
using softwares like word processors and image processing softwares.

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1.6 SEMINAR REPORT ORGANISATION
cover page
acknowledgment
abstract
1.0. INTRODUCTION …………………………………………………………… 1
1.1 background 6
1.2 objectives of the seminar……………………………………………… 7
1.3 significance of the seminar……………………………………………… 8
1.4 scope of the seminar ………………………………………………… 9
1.5 constraints and limitations…………………………………………… 10
1.6 seminar report organisation……………………………………………… 11
2.0 LITERATURE REVIEW…………………………………………………..……… 11
3.0 DISCUSSION………………………………………………………………………12
3.1 Types of Watermarking…………..…………………………………… 12
3.2 Attributes associated with the Watermarking…………………………… 13
3.3 applications…………………………………………………………… 14
3.4 Watermarking properties…………………………………………………… 17
3.5 Watermarking models…………….…………………………………… 18
4.0 CONCLUSION………………………………………………………………… 20
5.0 REFERENCES………………………………………………………………… 21

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2.0 LITERATURE REVIEW
A digital watermark is a kind of marker covertly embedded in a noise-tolerant signal such as an audio,
video or image data. It is typically used to identify ownership of the copyright of such signal.
“Watermarking” is the process of hiding digital information in a carrier signal; the hidden
information should, but does not need to, contain a relation to the carrier signal. Digital watermarks
may be used to verify the authenticity or integrity of the carrier signal or to show the identity of its
owners. It is prominently used for tracing copyright infringements and for banknote
authentication.Like traditional physical watermarks, digital watermarks are often only perceptible
under certain conditions, i.e. after using some algorithm. Traditional watermarks may be applied to
visible media (like images or video), whereas in digital watermarking, the signal may be audio,
pictures, video, texts or 3D models. A signal may carry several different watermarks at the same time.
Unlike metadata that is added to the carrier signal, a digital watermark does not change the size of
the carrier signal.
The needed properties of a digital watermark depend on the use case in which it is applied. For
marking media files with copyright information, a digital watermark has to be rather robust against
modifications that can be applied to the carrier signal. Instead, if integrity has to be ensured, a fragile
watermark would be applied.
Since a digital copy of data is the same as the original, digital watermarking is a passive protection
tool. It just marks data, but does not degrade it or control access to the data.
One application of digital watermarking is source tracking. A watermark is embedded into a digital
signal at each point of distribution. If a copy of the work is found later, then the watermark may be
retrieved from the copy and the source of the distribution is known. This technique reportedly has
been used to detect the source of illegally copied movies. (Ingemar J.Cox:Digital watermarking and
steganography. Morgan Kaufmann, Burlington, MA, USA, 2008)

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3.0 DISCUSSION
The digital watermarking or watermarking explains the ways and mechanisms to hide the data and
the data can be a number or text, in digital media, it may be a picture or video. The watermarking is
a message that can be embedded into the digital data like video, pictures, and text and the embedded
data can be extracted later. The steganography is also another form of watermarking and in this, the
messages are hidden in the content without making the people to note its presence. The Indian
currency is a good example of watermarking and in the general watermarking procedure the genuine
image undergoes the embedding procedure along with the watermark and the output generated will
be a watermarked image.
3.1 Types of Watermarking
The digital watermarking is of four types and they are as follows:
• Visible
• Invisible
• Fragile
• Public
1. Visible watermarking: the visible watermarking have the visible message or the logo of the
company which represents the ownership of the message, removing of the logo and meddling of the
logo breaks the law of copyright.
2. Invisible watermarking: the invisible watermarking cannot be seen on the original images
and the picture looks like an original image though it has the watermark. The invisible watermark can
be extracted with the detection procedure or with any watermark extraction method.
3. Fragile watermark: the fragile watermarks can be demolished by the data manipulation and
these are also called as tamper proof watermark. The fragile watermark has the ability to detect the

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modifications in the signal and also recognizes the place where the modifications have occurred and
also the signal before the change.
4. Public watermark: The public watermark does not have the protection and these can be read
by everyone by availing the unique algorithm. (Frank Y. Shih: Digital watermarking and
steganography: fundamentals and techniques. Taylor & Francis, Boca Raton, FL, USA, 2008)
3.2 Attributes associated with the Watermarking:
• Imperceptibility
• Robustness
• Security
• Complexity
• Verification
Imperceptibility: The imperceptibility means that the watermark should not be visible to the human
visible system as the watermark should look like genuine.
Robustness: The robust meaning is nothing but the strength of the watermark to obstruct the
manipulations of the media like the compression, scaling and cropping. The definition of the
robustness explains that the watermark can be detected after the operations on te content, the
operations are like filtering, compression, color correction and geometrical changes.
Security: The security is nothing but the integrated watermark and cannot be removed by the attacks
and the images possessing this feature does not reveal any clue about the presence of the watermark
in it.
Complexity: The complexity explains about the difficulty and the time needed for the watermark
embedding.
Verification: The verification is a process and it has a private key function or a public key function.

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3.3 Applications
Digital Watermarks are potentially useful in many applications, including:
1. Ownership assertion: Watermarks can be used for ownership assertion. To assert ownership
of an image, Alice can generate a watermarking signal using a secret private key, and then embed it
into the original image. She can then make the watermarked image publicly available. Later, when
Bob contends the ownership of an image derived from this public image, Alice can produce the
unmarked original image and also demonstrate the presence of her watermark in Bob’s image. Since
Alice’s original image is unavailable to Bob, he cannot do the same. For such a scheme to work, the
watermark has to survive image processing operations aimed at malicious removal. In addition, the
watermark should be inserted in such a manner that it cannot be forged as Alice would not want to be
held accountable for an image that she does not own.
2. Fingerprinting: In applications where multimedia content is electronically distributed over a
network, the content owner would like to discourage unauthorized duplication and distribution by
embedding a distinct watermark (or a fingerprint) in each copy of the data. If, at a later point in time,
unauthorized copies of the data are found, then the origin of the copy can be determined by retrieving
the fingerprint. In this application the watermark needs to be invisible and must also be invulnerable
to deliberate attempts to forge, remove or invalidate. Furthermore, and unlike the ownership assertion
application, the watermark should be resistant to collusion. That is, a group of k users with the same
image but containing different fingerprints, should not be able to collude and invalidate any
fingerprint or create a copy without any fingerprint.
3. Copy prevention or control: Watermarks can also be used for copy prevention and control.
For example, in a closed system where the multimedia content needs special hardware for copying
and/or viewing, a digital watermark can be inserted indicating the number of copies that are permitted.
Every time a copy is made the watermark can be modified by the hardware and after a point the

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hardware would not create further copies of the data. An example of such a system is the Digital
Versatile Disc (DVD). In fact, a copy protection mechanism that includes digital
watermarking at its core is currently being considered for standardization and second generation DVD
players may well include the ability to read watermarks and act based on their presence or absence.
Another example is in digital cinema, where information can be embedded as a watermark in every
frame or a sequence of frames to help investigators locate the scene of the piracy more quickly and
point out weaknesses in security in the movie’s distribution. The information could include data such
as the name of the theatre and the date and time of the screening. The technology would be most
useful in fighting a form of piracy that’s surprisingly common, i.e., when someone uses a camcorder
to record the movie as it’s shown in a theatre, then duplicates it onto optical disks or VHS tapes for
distribution.
4. Fraud and tamper detection: When multimedia content is used for legal purposes, medical
applications, news reporting, and commercial transactions, it is important to ensure that the content
was originated from a specific source and that it had not been changed, manipulated or falsified. This
can be achieved by embedding a watermark in the data. Subsequently, when the photo is checked,
the watermark is extracted using a unique key associated with the source, and the integrity of the data
is verified through the integrity of the extracted watermark. The watermark can also include
information from the original image that can aid in undoing any modification and recovering the
original. Clearly a watermark used for authentication purposes should not affect the quality of an
image and should be resistant to forgeries. Robustness is not critical as removal of the watermark
renders the content inauthentic and hence of no value.
5. ID card security: Information in a passport or ID (e.g., passport number, person’s name, etc.)
can also be included in the person’s photo that appears on the ID. By extracting the embedded
information and comparing it to the written text, the ID card can be verified. The inclusion of the
watermark provides an additional level of security in this application. For example, if the ID card is

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stolen and the picture is replaced by a forged copy, the failure in extracting the watermark will
invalidate the ID card.
The above represent a few example applications where digital watermarks could potentially be of use.
In addition there are many other applications in rights management and protection like tracking use
of content, binding content to specific players, automatic billing for viewing content, broadcast
monitoring etc. From the variety of potential applications exemplified above it is clear that a digital
watermarking technique needs to satisfy a number of requirements. Since the specific requirements
vary with the application, watermarking techniques need to be designed within the context of the
entire system in which they are to be employed. Each application imposes different requirements and
would require different types of invisible or visible watermarking schemes or a combination thereof.
In the remaining sections of this chapter we describe some general principles and techniques for
invisible watermarking. Our aim is to give the reader a better understanding of the basic principles,
inherent trade-offs, strengths, and weakness, of digital watermarking. (Cox I, Miller M, Bloom J,
Fridrich J, Kalker T(2008) Digital Watermarking and Steganography Second Edition. Elsevier, 2008)
3.4 Watermarking properties
Every watermarking system has some very important desirable properties. Some of these properties
are often conflicting and we are often forced to accept some trade offs between these properties
depending on the application of the watermarking system.
The first and perhaps most important property is effectiveness. This is the probability that the message
in a watermarked image will be correctly detected. We ideally need this probability to be 1.
Another important property is the image fidelity. Watermarking is a process that alters an original
image to add a message to it, therefore it inevitably affects the image’s quality. We want to keep this
degradation of the image’s quality to a minimum, so no obvious difference in the image’s fidelity can
be noticed.

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The third property is the payload size. Every watermarked work is used to carry a message. The size
of this message is often important as many systems require a relatively big payload to be embedded
in a cover work. There are of course applications that only need a single bit to be embedded.
The false positive rate is also very important to watermarking systems. This is the number of digital
works that are identified to have a watermark embedded when in fact they have no watermark
embedded. This should be kept very low for watermarking systems.
Lastly, robustness is crucial for most watermarking systems. There are many cases in which a
watermarked work is altered during its lifetime, either by transmission over a lossy channel or several
malicious attacks that try to remove the watermark or make it undetectable. A robust watermark
should be able to withstand additive Gaussian noise, compression, printing and scanning, rotation,
scaling, cropping and many other operations.
3.5 Watermarking models
There are several ways in which we can model a watermarking process. These can be broadly
classified in one of two groups. The first group contains models which are based on a communication-
based view of watermarking and the second group contains models based on a geometric view of
watermarking.
3.5.1 Communication-based models
Communication-based models describe watermarking in a way very similar to the traditional models
of communication systems. Watermarking is in fact a process of communicating a message from the
watermarking embedder to the watermarking receiver. Therefore, it makes sense to use the models
of secure communication to model this process.

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In a general secure communication model we would have the sender on one side, which would encode
a message using some kind of encoding key to prevent eavesdroppers to decode the message if the
message was intercepted during transmission. Then the message would be transmitted on a
communications channel, which would add some noise to the noise to the encoded message. The
resulting noisy message would be received at the other end of the transmission by the receiver, which
would try to decode it using a decoding key, to get the original message back. This process can be
seen in Figure 1.
3.5.2 Geometric models
It is often useful to think of watermarking in geometric terms. In this type of model, images,
watermarked and un watermarked, can be viewed as high-dimensional vectors, in what is called the
media space. This is also a high-dimensional space that contains all possible images of all dimensions.
For example a 512 X 512 image would be described as a 262144 elements vector in a 262144-
dimensional space.
Geometric models can be very useful to better visualize the watermarking process using a number of
regions based on the desirable properties of watermarking. One of these regions is the embedding
region, which is the region that contains all the possible images resulting from the embedding of a
message inside an un watermarked image using some watermark embedding algorithm. Another very

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important region is the detection region, which is the region containing all the possible images from
which a watermark can be successfully extracted using a watermark detection algorithm. Lastly, the
region of acceptable fidelity contains all the possible images resulting from the embedding of a
message into an un watermarked image, which essentially look identical to the original image. The
embedding region for a given watermarking system should ideally lie inside the intersection of the
detection region and the region of acceptable fidelity, in order to produce successfully detected
watermarks that do not alter the image quality very much.
An example of a geometric model can be seen in Figure 2. Here we can see that if mean square error
(MSE) is used as a measure of fidelity, the region of acceptable fidelity would be an n-dimensional
sphere centred on the original un watermarked image (co), with a radius defined by the largest MSE
we are willing to accept for images with acceptable fidelity. The detection region for a detection
algorithm based on linear correlation would be defined as a half space, based on the threshold used
to decide whether an image has a watermark embedded or not. (Costa M (1983) Writing on dirty
paper. IEEE Transactions in Information Theory, 29:439–441, 1983)

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4.0 CONCLUSION
Watermarking is a very active research field with a lot of applications. Although it is a relatively new
field, it has produced important algorithms for hiding messages into digital signals. These can be
described by many different models. Two broad categories for these models were described in this
essay. These are communication- based models and geometric models. Communication-based models
can be further divided into those which use side-information and those that don’t. One example
system was used to illustrate non-side-information models, and two example systems were used to
illustrate side-information models. Each of these systems has its advantages and disadvantages, and
each one trades some important watermarking property for another. The choice of which to use relies
on the underlying application’s requirements.
Of course the examples provided in this essay are only a small sample of the many different
approaches to watermarking. Examples of other approaches that have not been mentioned include
those which operate in the frequency domain and take advantage of DCT coefficient and wavelet
coefficients.

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5.0 REFERENCES
1. IngemarJ.Cox:Digital watermarking and steganography. Morgan Kaufmann, Burlington,
MA, USA, 2008
2. Frank Y. Shih: Digital watermarking and steganography: fundamentals and techniques.
Taylor & Francis, Boca Raton, FL, USA, 2008
3. A.Z.Tirkel, G.A. Rankin, R.M. Van Schyndel, W.J.Ho, N.R.A.Mee, C.F.Osborne.
“Electronic Water Mark”. DICTA 93, Macquarie University. p.666-673
4. Zigomitros Athanasios; Papageorgiou Achilleas; Patsakis Constantinos (25 June 2012).
Social network content management through watermarking. 2012 IEEE 11th International
Conference on Trust, Security and Privacy in Computing and Communications
(TrustCom). Liverpool. pp. 1381––1386.
5. Khan, A. and Mirza, A. M. 2007. Genetic perceptual shaping: Utilizing cover image and
conceivable attack information during watermark embedding. Inf. Fusion 8, 4 (Oct. 2007),
354-365
6. “CPTWG Home Page”. cptwg.org.
7. Paul Blythe; Jessica Fridrich, Secure Digital Camera (PDF)
8. Saraju Mohanty, Nagarajan Ranganathan, and Ravi K. Namballa, VLSI Implementation of
Visible Watermarking for a Secure Digital Still Camera Design (PDF), archived from the
original (PDF) on 2016-03-04
9. Toshikazu Wada; Fay Huang (2009), Advances in Image and Video Technology, pp. 340–
341, ISBN 978-3-540- 92956-7
10. Unretouched by human hand,TheEconomist,December 12, 2002
11. Raju Halder; Shantanu Pal; Agostino Cortesi,
Watermarking Techniques for Relational Databases: Survey, Classification and Comparison
(PDF), The Journal of Universal Computer Science, vol 16(21), pp. 3164-3190, 2010.hell0
12. Cox I, Miller M, Bloom J, Fridrich J, Kalker T (2008) Digital Watermarking and
Steganography Second Edition. Elsevier, 2008
13. Costa M (1983) Writing on dirty paper. IEEE Transactions in Information Theory, 29:439–
441, 1983

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