Block Size Analysis for Discrete Wavelet Watermarking
and Embedding a Vector Image as a Watermark
Hayri Sever1, Ahmet Şenol1, and Ersin
Elbaşı2
1Department
of Computer Engineering, Çankaya University,
06790 Etimesgut Ankara
2College
of Engineering and Technology, American University of the Middle East, Kuwait
Abstract: As telecommunication and computer technologies
proliferate, most data are stored and transferred in digital format. Content
owners, therefore, are searching for new technologies to protect copyrighted
products in digital form. Image watermarking emerged as a technique for
protecting image copyrights. Early studies on image watermarking used the pixel
domain whereas modern watermarking methods convert a pixel based image to
another domain and embed a watermark in the transform domain. This study aims
to use, Block Discrete Wavelet Transform (BDWT) as the transform domain for
embedding and extracting watermarks. This study consists of 2 parts. The first
part investigates the effect of dividing an image into non-overlapping blocks
and transforming each image block to a DWT domain, independently. Then, effect
of block size on watermark success and, how it is related to block size, are
analyzed. The second part investigates embedding a vector image logo as a
watermark. Vector images consist of geometric objects such as lines, circles
and splines. Unlike pixel-based images, vector images do not lose quality due
to scaling. Vector watermarks deteriorate very easily if the watermarked image
is processed, such as compression or filtering. Special care must be taken when
the embedded watermark is a vector image, such as adjusting the watermark
strength or distributing the watermark data into the image. The relative
importance of watermark data must be taken into account. To the best of our
knowledge this study is the first to use a vector image as a watermark embedded
in a host image.
Keywords: Watermarking, DWT, block, vector, SVG.