Samenvatting
The aim of the thesis is to implement a watermarking scheme for still images. Watermarkingis the practice of hiding a message about an image, audio clip, video clip, or other work
of media within that work itself. In the context of image processing, it is a must that the
watermarking of an image is not perceptible. The used technique is based on recent literature
and compression standards: the scheme is applied on images that are transformed to
the wavelet domain. Wavelets are popular in modern compression applications. They are
used in multimedia applications because they support quality and resolution scalability as
well as interactive image manipulation.
Based on a series of experiments, the best parameters for the digital watermarking of
grayscale images are deduced.
The thesis is a first step in a new research domain for the ETRO department. It consists
of five main parts. The first chapter is an introduction, listing the possible applications for
watermarking. The second part situates the research domain of watermarking and explains
different existing watermarking techniques. In the third part, the implemented schemes
are explained in detail. The fourth chapter consists of experiments that were conducted.
The influence of several parameters is tested. The final experiment is conducted with an
optimal set of parameters. The maximum number of bits that can be embedded in a
512x512 image is 11907. For a robust watermark however, the number of bits that are
embedded can be reduced to 70. In this case, most of the attacks (addition of noise, image
compression, low- and high-pass filtering) that destroy the watermark also make the image
useless. That means that they fail in their purpose of making illegitimate use of the image.
In the last part of the thesis, conclusions are summarized and possible topics for future
research are proposed.
Datum prijs | 2007 |
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Originele taal | English |
Begeleider | Peter Schelkens (Promotor), Joeri Barbarien (Jury) & Tim Dams (Jury) |