What approaches could be to the subj problem? I mean, there is a camera, looking to a plane (say, a picture, list of paper). Initially, it's assumed to be placed right normally to surface. Then, it starts to move, and i want to recognize:
1) small translations, shifting image on surface
2) scalings of image due to camera moves up/down
3) small transformations, due to camera small rotations
Specifically, it'll be run on Android, so, free Android libs are preffered
Upd.: image on surface is not going to be apriori known, but it can be assumed to be black curves on white, say a text.