  A genetic algorithm based robust blind digital watermarking scheme is
presented. Starting from a binary image (the original watermark), a genetic
algorithm is performed searching for a permutation of this image which is as
uncorrelated as possible to the original watermark. The output of the GA is
used as our final watermark, so that both security and robustness in the
watermarking process is improved. Now, the original cover image is partitioned
into non-overlapped square blocks (depending on the size of the watermark
image). Then a (possibly extended) Hadamard transform is applied to these
blocks, so that one bit information from the watermark image is embedded in
each block by modifying the relationship of two coefficients in the transformed
matrices. The watermarked image is finally obtained by simply performing the
inverse (extended) Hadamard transform on the modified matrices. The
experimental results show that our scheme keeps invisibility, security and
robustness more likely than other proposals in the literature, thanks to the GA
pretreatment.
