|This kind of effect is very easy
conceptually. Just put a page-curl animation on a layer
above the layer that contains the picture to be revealed.
The most difficult part is creating the page curl
animation. Below is the animation that I created. It has
four key frames which are motion tweened to create the page
curl animation. This is not easy to create. It
takes several hours to create at least a smooth one like
this. Even then, I think it could be made better
(the paper looks like it's being pulled aside at the
end). This is a problem with motion tweening
gradient. More shape-hints might help, but this
will do for this example.
animation created with motion tween (uses shape hints).
Here's an onion skin view of the tween.
Once the animation tween is created, it can be placed on a
the image to create the page opening effect.