Seems like it is saying the following:
We can find the watermark in images and subtract it from the image. If we distort the original watermark, but subtract the average watermark, then you will not recover the original image.
duh?
We can find the watermark in images and subtract it from the image. If we distort the original watermark, but subtract the average watermark, then you will not recover the original image.
duh?
Right now, sites like shutterstock and other image sites apply the same watermark to every image, making it quite easy to computationally extract the watermark, and then apply the inverse transform to marked images.
If the watermark is permuted on a per-image basis, it becomes much harder, since you can't extract the watermark from a single image.
azdle: That won't work, because "there's exactly one distinct watermark per image, so 1000 of the same image would have the same watermark."
Kdparker: So subtle alter the image, to trick the watermarker in to thinking the image isn't the same, thus generating more distinct watermarks for the (effectively) same image.