Algorithm Testing Overview
To find out how resistant our implemented watermarking algorithms are to attacks we devised a testing scheme that covers all common and malicious attacks. It is the point of testing to show in what ways certain watermarks are weaker than others. There is currently no watermark resistant to all image transformation attacks. It is important to prioritize these attacks from common to the most malicious. It is our hope that the implemented watermarking algorithms will be at least resistant to the most common of attacks. Complete watermark security is a goal that is currently unachievable and we are looking for about an 20% watermark recovery. A corollary of this is that a watermarkingmethod must first of all be robust against those transformations used by legalusers of the image. If watermark stands up against common attacks it is then important to concentrate on the various complex attacks that malicious attackers might employ. However, this is pointless if the method is not properly resistant to image edits made by either the original owner or valid users of the image. We state that, roughly in order of importance, a watermarking method must handle:
· Scaling, especially
Some of the malicious attacks listed below:
Image modification attacks. These use image transformations such as those isted above.
averaging attacks. The attacker uses multiple watermarked images
to estimate the watermark, and then subtracts this from the image. This
is especially a problem with video.
attacks. By inserting a scrambler before the watermark
Editing watermarked images in Photoshop will
do some of the testing but majority
Correlations of attacked watermarked images
with that of original watermarked