[topherclay]

Of course. the first image of the blog post shows that you can "paint over" the largely unused area and you don't lose much of your original image. The hidden watermarks make use of this unused area so you can just paint over that area with blank data in order to "scrub" any hidden watermarks.

[forgotusername6]

I'm pretty sure you could also layer the cat noise evenly over the image without significantly damaging the woman. The DCT puts all the importantly information top left, but there is nothing stopping you adding a step to distribute that information across the whole image, or using another transform that didn't have the same concentration effect

[topherclay]

Well sure, but whatever extra step you use to encode you will also need as an extra step to decode.