50120130406038

International Journal of Computer Engineering and Technology (IJCET), ISSN 0976-6367(Print),
INTERNATIONAL JOURNAL OF COMPUTER ENGINEERING &
ISSN 0976 - 6375(Online), Volume 4, Issue 6, November - December (2013), © IAEME

TECHNOLOGY (IJCET)

ISSN 0976 – 6367(Print)
ISSN 0976 – 6375(Online)
Volume 4, Issue 6, November - December (2013), pp. 347-354
© IAEME: www.iaeme.com/ijcet.asp
Journal Impact Factor (2013): 6.1302 (Calculated by GISI)
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IJCET
©IAEME

COMPARATIVE ANALYSIS OF DIGITAL WATERMARKING BASED ON
EMBEDDING AND EXTRACTION TECHNIQUE
Mrs. Rashmi Soni1,

Dr. M.K. Gupta2

1

2

Research Scholar, Department of CSE, AISECT University, Bhopal
Research Supervisor, AISECT University & Professor, Department of ECE, MANIT, Bhopal

ABSTRACT
Digital watermarking knowledge is a leading edge research field and it mainly focuses on the
intellectual property rights, hides data and embedded inside an image to show authenticity or proof
of ownership, discovery and authentication of the digital media to protect the important documents.
Digital watermarking can help to verify ownership, to recognize a misappropriate person and find the
marked documents. One of the significant technological actions of the last two decades was the
attack of digital media in a complete range of everyday life aspects.
Digital data can be stored efficiently with a very high quality and it can be manipulated very
easily using computers. In addition digital data can be transmitted in a fast and inexpensive way
through data communication networks without losing quality. According to the necessary study of
digital image watermarking, the digital watermarking model consists of two modules, which are
watermark embedding module and watermark extraction and detection module.
Keywords: Digital watermarking, Digital image watermarking, Embedding, Extraction.
1. INTRODUCTION
The digital data can be transmitted in a fast and cheap way through data communication
networks not including losing quality. Digital media offer numerous different advantages over
analog media. The quality of digital audio, images and video signals are superior to that of their
analog counterparts. Editing is easy because one can allow the exact discrete locations that need to
be changed. Copying is easy with no loss of information and a copy of a digital media is related to
the original.
In case of watermarking, the digital multimedia distribution over World Wide Web,
Intellectual Property Rights (IPRs) are more in risky than ever due to the possibility of unlimited
copying. This difficulty can be handled by hiding some ownership data into the multimedia data,
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which can be extracted afterwards to prove the ownership, a concept called “watermarking”.
Everyday, in general, a lot of data is embedded on digital media or spread over the internet. This
data, which include still images, video, audio, or text are stored and transmitted in a digital format
can be easily copied without loss of quality and well distributed [1].
The protection of intellectual property rights has become more and more important. Information
stored in digital format because of simplicity of reproduction, retransmission and even manipulation
allows a pirate either to get rid of a watermark and go against a copyright or to transmit the same
watermark after changing the data to copy the proof of authenticity [6]. The design of techniques for
preserving the ownership of digital information is in the beginning of the development of upcoming
multimedia services.
1.1 Digital Image Watermarking
Proof of ownership of data is done by embedding copyright statements.
Embedding

Watermarking

Detection

Data, Signature

Data, Signature

ID etc

ID etc

Fig1.1 Block Diagram of Digital Image Watermarking

As shown in figure1.1 for watermarking, embedding and detection mainly consist of a key,
digital data, signature id etc in which a key and digital data embeds watermarked digital data and a
key and digital data detects watermark. An existing scheme for still image watermarking in spatial
domain is studied. Watermark is embedded and retrieval of embedded watermark is easy in this way.
Cryptography can be used which ensures confidentiality, authenticity and integrity.
To explain the above figure of digital image watermarking more accurately, which consists of
elements of watermarking system that uses watermark signal, that passes through embedder which is
communicated with respect to channel & finally detection is done. Digital watermarking technology,
is directly related to information security, information hiding, cryptography and authentication
technologies, is a cutting edge research area of the international academic research in current years.
Currently, the quick development of network of information and e-commerce make digital
watermarking technology very important for all types of digital products protection, and its use is
becoming increasingly more widespread. All these place higher demands for people to plan an
enhanced watermarking algorithm. It must be common that digital watermarking technology
requirements to be mutual with these disciplines and technologies so as to oppose all kinds of attacks
and structure integrated solutions for digital products copyright protection. The requirement for this
type of technology can be predictable to grow extremely as businesses request to declare some
control over their property on the “freeness” Internet. Digital image watermarking methods can be
modeled as communication method involving an embedder and detector as shown in Figure1.2.

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Cover Image

Watermarked
signal

Watermark
embedder

Stego
image

Watermark
detector

Detected
watermark
signal

Fig1.2 Basic Watermarking Method

2. VARIOUS DIGITAL WATERMARKING TECHNIQUES
2.1 Related to Document
Watermarking techniques can also be divided into four categories, according to the type of
document to be watermarked, as follows:
a) Image Watermarking: Image is watermarked using a main image, original mage and finally
image is then watermarked. This is used to hide the special information into the image and to later
detect and extract that special information for the author‘s ownership.
b) Audio watermarking: This application area is one of the most popular and happening issue due
to internet music, MP3.
c) Video watermarking: This adds watermark in the video stream to classify video applications. It
is the development of image watermarking. This method requires real time extraction and robustness
for compression.
d) Text watermarking: This adds watermark to the PDF, DOC and other text file to prevent the
changes made to text. The watermark is inserted in the font shape and the space between characters
and line spaces.
e) Graphic watermarking: It embeds the watermark to 2D or 3D computer generated graphics to
indicate the copyright.
2.2 Related to Human Perception
According to the human perception, the digital watermarks can be divided into 4 different
types: Visible watermark, Invisible-Semi fragile watermark, fragile watermark, robust watermark.
a) Visible watermark: This is a secondary transparent overlaid into the primary image. The
information is visible in the picture. Typically, the information is text or a logo, which identifies the
owner of the media.
b) Invisible watermark: There is technology available which can insert information into an image
which cannot be seen. We cannot prevent the theft of our images this way, but we can prove that the
image that was stolen was ours, which is almost as good.

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c) Robust watermark: Embedded invisible watermarks. It prevents image processing or attacks
without affecting embedded watermark. It is against challenging based attack (e.g. noise addition to
images), mainly used in copy protection application.
d) Fragile Watermark: The fragile watermark is embedded in such a way that any manipulation or
modification of the image would change or destroy the watermark. Fragile watermarks are destroyed
by data manipulation, mainly used for tamper detection.
e) Semi Fragile Watermark: This is sensitive to signal modification containing feature of both
robust and fragile watermarks which provide data authentication. This, in nature, is robust against
user-level operation (e.g. image compression).
2.3 Related to Application Domain
According to application domain, source-based watermarks are desirable for ownership
identification or authentication where a single watermark identifies the owner. A source based
watermark could be used for authentication and to determine whether a received image or other
electronic data has been tampered.
The watermark could also be destination based where each distributed copy gets a single
watermark identifying the particular buyer. The destination based watermark could be used to trace
the buyer in the case of illegal reselling. This is used in fingerprinting.
2.4 Related to Watermarking Domain
Based on their embedding domain, watermarking schemes can be classified as follows:
a) Spatial Domain: The watermarking system directly alters the main data elements (like pixels in
an image) to hide the watermark data. Spatial domain digital watermarking algorithms directly load
the raw data into the original image [2]. Spatial watermarking can also be applied using color
separation. In this way, the watermark appears in only one of the color bands.
b) Frequency Domain: The watermarking system exchange the frequency transforms of data
elements to hide the watermark data. This has proved to be more robust than the spatial domain
watermarking. The aim is to embed the watermarks in the spectral coefficients of the image. The
most commonly used transforms are the Discrete Cosine Transform (DCT), Discrete Fourier
Transform (DFT), Discrete Wavelet Transform (DWT), the reason for watermarking in the
frequency domain is that the characteristics of the human visual system (HVS) are better captured by
the spectral coefficients [3].
c) Feature Domain: The watermarking system takes into account the region, boundary and object
characteristics. It presents better detection and recovery from attacks.
3. REQUIREMENTS OF DIGITAL WATERMARKING
The requirements of digital watermarking are:
There are a number of important characteristics that a watermark can exhibit. The most
important properties of digital watermarking techniques are transparency, robustness, security,
capacity, invert ability (reversibility) and complexity and possibility of verification.

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a) Transparency: The quality of the embedded watermark should be clear and transparent. The
embedded watermark should not reduce the quality of the original image. It relates to the properties
of the human sensory. A translucent watermark never causes any type of quality loss.
b) Robustness: Robustness means resistance to blind, non-targeted changes, or common media
operations on basis of the requirements for watermark extraction [5].There are various types of
attack for destroying the watermark such as cropping, compression, scaling etc. The watermark
should be design in such a way that, it is invariant to all attacks. There are two major problems when
trying to guaranty robustness; the watermark must be still present in the media after the
transformation or it must be still possible for the watermark detector to detect it. When a signal is
distorted, its reliability is only preserved if it’s perceptually important region remain undamaged,
while perceptually unimportant regions might be extensively changed with little effect on reliability.
c) Security: Security describes whether the embedded watermarking information cannot be removed
beyond constant detection by targeted attacks based on a full awareness of the embedding algorithm
and the detector, except the key, and the knowledge of at least one watermarked data. Watermarking
security implies that the watermark should be difficult to remove or alter without damaging the host
signal. As all watermarking systems request to protect watermark information, without loss of
generality, watermarking security can be regarded as the ability to guarantee secrecy and integrity of
the watermark information, and resist malicious attacks [4].
d) Capacity: Capacity describes the maximum amount of data that can be embedded into image,
audio, video or text for suitable retrieval of watermark during extraction. Capacity describes how
many information bits can be embedded. It addresses also the opportunity of embedding multiple
watermarks in one document in parallel. Capacity requirement always struggle against two other
essential requirements, that is, imperceptibility and robustness. A higher capacity is usually obtained
at the cost of either robustness strength or imperceptibility.
e) Imperceptibility: watermark should not be visible to the viewer neither the watermark corrupt the
value of the content. The term imperceptible is widely used in this case. If a signal is accurately
imperceptible, then perceptually based lossy compression algorithms either introduce further changes
that jointly exceed the visibility threshold or avoid such a signal. It is then essential to expand
techniques that can be used to add imperceptible or unnoticeable watermark signals in perceptually
significant regions to oppose the effects of signal processing.
f) Modification and Multiple Watermarks: Altering a watermark can be done by either removing
the first watermark or then adding a new one, or inserting a second watermark. The first option goes
against the rule of tamper resistance, because it implies that a watermark is easily removable.
Allowing various watermarks to coexist is the ideal solution. There is, still a security problem
associated to the use of multiple watermarks. It means that watermarking security can be interpreted
as encryption security leading directly to the principle that it must be positioned mainly in the choice
of the embedded key. These allows insertion of multiple, independently noticeable watermarks in an
image.
g) Invertibility: Invertibility describes the chance to produce the original data during the watermark
retrieval. The optimization of the parameters is equally competitive and cannot be clearly done at the
same time. If we want to embed a large message, we cannot need large robustness at the same time.
A practical compromise is always a need. Hence, if robustness to strong distortion is an issue, the
message that can be reliably hidden must not be too long.
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4. EMBEDDING AND EXTRACTION
Digital watermarking involves the ideas and theories of different subject coverage, such as
signal processing, cryptography, probability theory, network technology, algorithm design, and other
techniques [3].
Digital watermarking hides the copyright information into the digital data through certain
algorithm. The secret information to be embedded can be some text, author‘s serial number,
company logo, images with a number of special importance. This secret information is embedded to
the digital data (images, audio, and video) to guarantee the security, data authentication,
identification of owner and copyright protection. The watermark can be hidden in the digital data
either visibly or invisibly. The process of embedding the watermark requires modifying the original
image and in essence the watermarking process inserts a controlled amount of “distortion” in the
image. The recovery of this distortion allows the one to identify the owner of the image. Invisible or
transparent marks use the properties of the human visual system to minimize the perceptual
distortion in the watermarked image [7].
For a strong watermark embedding, a good watermarking technique is needed to be applied.
Watermark can be embedded either in spatial or frequency domain. Both the domains are different
and have their own pros and cons and are used in different situation.
4.1 Watermarking Algorithm
a) Embedding Algorithm
1. Generate ‘e’ with the secret key shared with the detector.
2. For each pixel i in image h
a) Calculate the secret dependency P (i) according to
P (i) = ∑ (e (i) ⊕ e (j)) (-1) e (j) h M (j)
j Є N (i)
where ⊕ denotes the (XOR) operation.

---------- (1)

b) Adjust h1 (i) so that the following equation holds
Parity (h (i) +P (i)) = e (i)

------------ (2)

Simple Digital watermarking is a technology in which a watermark (secret information) is
hidden in the digital media using an appropriate algorithm for the authentication and identification of
unique owner of the product. Outcome we get is watermarked image. Simple digital watermarking
technique consists of two modules watermark embedding module and watermark detection and
extraction module. Watermark embedding embeds the watermark into the original image using a key
[2]. The watermark embedding module is shown in Fig 4.1.
Key

Watermark
Watermark
embedded
Original works

module

Works with watermark
Fig 4.1 Watermark Embedding Module
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b) Detection Algorithm
1. Generate ‘e’ with the secret key shared with the embedder.
2. For each pixel ‘p’,
a) Calculate the secret dependency P (i) from the received image h′ according to Eq (1)
b) Extract the watermark bit e′ (i) according to:
e′ (i) = Parity (h′ (i) +P (i))

----------- (3)

c) Calculate C(i) between e(i) and e'(i) using:
C (i) = 0 will be e (i) = e′ (i) or, 255 otherwise ---------- (4)
Watermark detection and extraction module is used to determine whether the data contains
specified watermark or the watermark can be extracted [2]. The watermark embedding module is
given in Fig 4.2.

Works to be
detected

Watermark

Key

detection
module

Original works

Watermark

Fig 4.2 Watermark Detection and Extraction Module

V. CONCLUSION
The beginning work carried out on digital watermarks has been described, including the brief
study of various watermarking schemes, requirements, techniques and its potential applications.
Some of the watermarking techniques carried out with their pros and cons have been discussed. It
firstly provided a general description of the attractive characteristics of digital watermarking system.
Various watermarking techniques are discussed in short with the possible applications of the
watermarking methodology. Finally, certain points are summarized based on embedding and
detection technique. Watermarking provides owner authentication.
REFERENCES
[1]
[2]

[3]

http://en.wikipedia.org/wiki/Digital_watermarking.
Jiang Xuehua, “Digital Watermarking and Its Application in Image Copyright Protection”,
International Conference on Intelligent Computation Technology and Automation, TBD
Changsha, China, 11-12 May 2010.
Manpreet Kaur, Sonia Jindal, Sunny Behl, “A Study of Digital image watermarking”, Vol 2,
Issue 2, Feb 2012.
353


[4]

C.-T. Li and F.M. Yang., “One-dimensional Neighborhood Forming Strategy for Fragile
Watermarking”, Journal of Electronic Imaging, Vol. 12, Issue No. 2, pp. 284-291, 2003.
[5] Ahmed Salma, Randa Atta, and Rawya Rizk, “A Robust Digital Image Watermarking
Technique Based on Wavelet Transform” IEEE International Conference on System
Engineering and Technology (ICSET), University of Technology, Mara (UTM),
Shah Alam, Malaysia, 2011.
[6] Liu J. and He X., “A Review Study on Digital Watermark, Information and Communication
Technologies”, International Conference (ICICT), pp. 337-341, 2005.
[7] R. B. Wolfgang, C. I. Podilchuk, and E. J. Delp, "Perceptual Watermarks for Digital Images
and Video", Proceedings of the IEEE, Vol. 87, No. 7, pp. 1108-1126, July 1999.
[8] Karimella Vikram, Dr. V. Murali Krishna, Dr. Shaik Abdul Muzeer and K. Narasimha,
“Invisible Water Marking within Media Files using State-of-the-Art Technology”,
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2012, pp. 1 - 8, ISSN Print: 0976 – 6367, ISSN Online: 0976 – 6375.
[9] N. R. Bamane, Dr. S. B. Patil, Prof. B. S. Patil and Prof. R. K. Undegaonkar, “Hybrid Video
Watermarking Technique by using DWT & PCA”, International Journal of Electronics and
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[10] G. B. Khatri and D. S. Chaudhari, “Digital Audio Watermarking Applications and
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ISSN Online: 0976 –6472.

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