>Images can be cropped, rotated, recompressed, scaled, etc. and the digital watermark remains.

And none of those would impact the timing of black interim time lengths.

Also, this makes digimarc sound crappy (from their site):

>Facebook compresses images once they are posted, sometimes heavily, which can damage our invisible identifiers. Fortunately, there is a simple solution: if you pre-compress your images, then apply our identified, they should survive.

So they don't survive compression.

"And that's just my stupid of-the-cuff answer, which is already off to a decent start. And there are in fact purely-spatial solutions that do work, to which the temporal solutions can be added."