Digital Watermarking
-Interim Report (EE5359: Multimedia processing)
Under the Guidance of Dr. K. R. Rao
Submitted by:
Ehsan Syed
1000671971
[email protected]
The University of Texas at Arlington – Spring 2011
Introduction
• Digital watermarking is based on the science
of steganography [1] or data hiding.
Steganography comes from the Greek
meaning ‘covered writing’.
• Steganography is defined as the practice of
undetectably altering a work to embed a
secret message. It is an area of research of
communicating in a hidden manner.
Introduction..
• Steganography and watermarking rely on
imperfections of human senses.
• The human eye has a limited dynamic range
so low quality images can be hidden within
high quality images [2].
Basic Principle
There are three main stages in the watermarking
process [3]:
• generation and embedding
• attacks
• retrieval/detection
Generation and Embedding
• Generation of watermarks is an important
stage of the process. Watermarks contain
information that must be unique otherwise
the owner cannot be uniquely identified.
• In embedding, an algorithm accepts the host
and the data to be embedded and produces a
watermarked signal. Various algorithms have
been developed so far [4-13].
Attacks
• The watermarked signal is then transmitted or
stored, usually transmitted to another person
• If this person makes a modification, this is
called an attack. There are many possible
attacks.
Retrieval/Detection
• Detection is an algorithm which is applied to
the attacked signal to attempt to extract the
watermark from it.
• If the signal was not modified during
transmission, then the watermark is still
present and it can be extracted.
Block diagram
Fig.1: Basic block diagram of digital watermarking
Types of watermarking
There are mainly three types of watermarking
[14]:
• Visible watermarking
• Invisible watermarking
• Dual watermarking
Techniques of watermarking
There are two major techniques of
watermarking [15]:
• Spatial domain: slightly modifies the pixels of
one or two randomly selected subsets of an
image
• Frequency domain: this technique is also
called transform domain. Values of certain
frequencies are altered from their original.
Project Goals
The goals of this project are:
• to embed a watermark into an image using
LSB technique
• compressing the watermarked image
• decompressing it
• extract the watermark from the image
Program for making watermarked
images
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host_image = input('Enter the host image file name with extension : ', 's') ;
wmrk_image = input('Enter watermark image file name with extension: ', 's');
host = imread(host_image);
wmrk = imread(wmrk_image);
figure(1)
imshow(host,[])
title('Host Image')
figure(2)
imshow(wmrk,[])
title('Watermark Image')
host=double(host);
wmrk=double(wmrk);
bits=3;
wmrk_shifted=bitshift(wmrk,-(8-bits));
for i=1:bits
host=bitset(host,i,0);
end
watermarked_image = uint8(host+wmrk_shifted);
figure(3)
imshow(watermarked_image,[])
title('Watermarked Image')
Host Image
Results so far
• Watermarked images are created
• JPEG compression and decompression will be
done in the final report
• Extraction of the watermark from the
watermarked image will be done in the final
report
Watermark Image
Visible Watermarked image
Invisible Watermarked image
References
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L.M. Marnel et al, “Spread spectrum image steganography”, IEEE Transactions on Image Processing, pp 10751083, Aug 1999
J.J.K O-Ruanaidh et al, “Watermarking digital images for copyright protection, IEE Proceedings in Vision”, Image
and Signal Processing, pp250-256, Aug 1996
I. J. Cox and M. L. Miller, “A review of watermarking and the importance of perceptual modeling”, Proceedings
of Electronic Imaging, February 1997
H.J. Wang et al, “Wavelet based digital image watermarking “, Optics Express, PP 491-496, Dec 1998
P.-T.Yu et al, “ Digital watermarking based on neural networks for color images”, Signal Processing, PP 663-671,
Mar 2001
J. O-Ruanaidh et al, “Cryptographic copyright protection for digital images based on watermarking techniques”,
Theoretical Computer Science, pp 117-142, Sep 1999
C. Fornaro and A.Sanna, “Public key watermarking for authentication of CSG models”, Computer-Aided design,
pp 727-735, Oct 2000
M. Barni et al, “Copyright protection of digital images by embedded unperceivable marks”, Image and Vision
Computing, pp897-906, Aug 1998
J.R. Hernandez et al, “Improving the performance of spatial watermarking of images using channel coding”,
Signal Processing, pp 1261-1279, July 2000
S. Pereira et al, “Optimal transform domain watermark embedding via linear programming”, Signal Processing,
pp 1251-1260, July 2001
F. Perez-Gonzalez et al, “Approaching the capacity limit in image watermarking: a perspective on coding
techniques for data hiding applications”, Signal Processing, pp 1215-1238, July 2001
R. Baitello et al, “From watermark detection to watermark decoding: a PPM approach”, Signal Processing, pp
1261-1271 , July 2001
M. Barni et al, “A DCT-domain system for robust image watermarking”, Signal Processing, pp 357-372, May
1998
S. P. Mohanty, et al, “A Dual Watermarking Technique for images”, Proceedings of the seventh ACM
international conference on Multimedia, pp 49-51, 1999
F. Hartung and M. Kutter, “Multimedia watermarking techniques”, Proceedings of the IEEE, Vol. 87, No. 7, pp
1079 – 1107, July 1999