I tried optar and did everything wrong i could find. I upscaled with gimp, upscaled not by a natural number, used a horrible laser printer with lots of artifacts, gray, thin, checkered recycling paper, folded it and it still worked. I was stunned. The decoder seems to be quite good, it can handle distortion reasonably well.

But it was only 50kB per page.

How does it compare to paperbak?