Looking through the internet i found an interesting toy called LUKA which claims to read out your books as you lay them in front of him. On further investigation Luka uses an Ingenic T20 Chip and has a Camera that points in the book direction. They almost certainly have to use some form of 2dfeature matching to see which book is in front of the toy. But what really bucks me out is that it reportively works offline with a bunch of picture books! So the hardware has to compute and compare 50 picture pages to the camera sensor in real time with rotation invariance! and all that on a small SoC
Someone has a guess on how they managed to do this?