You know those kids' books that have the bumpy plastic coating and when you turn the book one way you see one image - look at it from a different angle and you see another image?
This is the same concept. They have a bumpy plastic coating that sends the incoming light in different directions. They do some processing on standard images to determine how the scattering works and then use that scattering pattern to reconstruct new images.
I would view the bumpy coating as a myriad of lenses that change the character of the incoming light.
We have one of those windows in our bathroom with the glass that is warped so that it breaks up the light so much that it gives you privacy. I've often thought that it would be a fun project to create a camera system that you could calibrate to decrypt that scattered image by placing a known image behind the window and pre-determining how the light waves are refracted. It's cool to see that someone implemented something similar.