AntcuFaalb said:

Simple frame-blending can be undone...

Yes, but it has to be pretty simple. Most cases of frame blending involve decimation as well (i.e. NTSC to PAL) where you have only 5 frames for every 6 original frames. The blending effects can be improved, but you can never get the original 6 frames back. The analogy in audio is that you apply a low-pass filter and downsample. You can mitigate some of the low-pass filter, but you can never get the information above half of the new sampling rate back.

Not entirely relavent, but just pointing out that you are USUALLY screwed. ;)

-G