Is it possible to design an image that looks completely (or at least very) different when resized to a given (fixed) size?
This would be similar to the technique in Image that looks different on black background and on white, however using image resizing algorithms rather than gamma correction.
The idea would be, for instance, to supply a profile picture to a website which shows it in two different sizes, and have the viewers see starkingly different pictures in both cases. For instance, the word "YES" when seen in full-size, but "NO" when resized to a thumbnail.
This would of course depend on the resizing algorithm and on the source and target sizes, but for a given website (e.g. Facebook), these should remain (fairly) constant.