Article,
Optimizing Perceptual Shaping of a Digital Watermark Using Genetic Programming
Iranian Journal of Electrical and Computer Engineering (IJECE), 3 (2): 144--150 (Summer-Fall 2004)
Abstract
Embedding of a digital watermark in an electronic
document is proving to be a feasible solution for
copyright protection and authentication purposes. In
this paper, we present an innovative scheme of
perceptually shaping watermark to the cover images. A
watermark is generally embedded in the selected
coefficients of the transformed image using a carefully
chosen watermarking strength. Choice of a good
watermarking strength, to perceptually shape the
watermark according to the cover image is crucial to
make a tradeoff between the two conflicting properties,
namely: robustness and imperceptibility of the
watermark. Traditionally, a constant watermarking
strength obtained from spatial activity masking and
heuristics has been used for all the selected
coefficients during embedding. We consider this
tradeoff as an optimisation problem and have
investigated an evolutionary optimisation technique to
find optimal/near-optimal perceptual shaping function
for DCT based watermarking system. The new scheme
provides an excellent tradeoff between the robustness
and imperceptibility and is image adaptive. Improved
resistance to attacks, especially against JPEG
compression of quality 7percent and Gaussian noise of
variance 17000 has been observed
