2 research outputs found
Watermarking PDF Documents using Various Representations of Self-inverting Permutations
This work provides to web users copyright protection of their Portable
Document Format (PDF) documents by proposing efficient and easily implementable
techniques for PDF watermarking; our techniques are based on the ideas of our
recently proposed watermarking techniques for software, image, and audio,
expanding thus the digital objects that can be efficiently watermarked through
the use of self-inverting permutations. In particular, we present various
representations of a self-inverting permutation namely
1D-representation, 2D-representation, and RPG-representation, and show that
theses representations can be efficiently applied to PDF watermarking. Indeed,
we first present an audio-based technique for marking a PDF document by
exploiting the 1D-representation of a permutation , and then, since
pages of a PDF document are 2D objects, we present an image-based algorithm
for encoding into by first mapping the elements of into a
matrix and then using the information stored in to mark invisibly
specific areas of PDF document . Finally, we describe a graph-based
watermarking algorithm for embedding a self-inverting permutation into
the document structure of a PDF file by exploiting the RPG-representation
of and the structure of a PDF document. We have evaluated the embedding
and extracting algorithms by testing them on various and different in
characteristics PDF documents.Comment: 17 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1003.1796 by other author
On the steganographic image based approach to PDF files protection
Digital images can be copied without authorization and have to be protected.
Two schemes for watermarking images in PDF document were considered. Both
schemes include a converter to extract images from PDF pages and return the
protected images back. Frequency and spatial domain embedding were used for
hiding a message presented by a binary pattern. We considered visible and
invisible watermarking and found that spatial domain LSB technique can be more
preferable than frequency embedding using DWT.Comment: 7 pages, 8 figure