One question that needs to be addressed is how robust
is the watermark to typical image processing operations.
The first experiment examines the effect of mean and
median filtering on forgery detection. The test image consists
of a 768 x 512 pixel grayscale image. The watermark
block size was chosen to be 256 x 256 pixels. An msequence
with a period of 65,535 with a single zero bit
appended to the end of the sequence was used. It was
segmented into 256 bit sections, then arranged row by
row to form the watermark block. A 3 x 2 array of these
blocks formed the watermark, which covered the entire
image. Three different window sizes for each type of filter
were applied to two regions in the image. The goal was to
see if the watermark could be used to detect these alterations
to the image