This Android app is free and free from ads. It works pretty well for B&W even using my old Android device's 8mp camera. I am wondering if others use it and manage to get better results from a newer smartphone with a better camera on board. With my device, which is 4 years old, the results aren't as good as with a proper scanner, especially at the sides, but I could live with that if the center was near perfect. If you haven't used it I suggest you try it out if you want a scanner alternative. The maker is robably doing it for a hobby and seems vy friendly and open to suggestions. My Samsung tablet focuses very close, so I guess YMMV depending how close your smarthone can focus. My iPhone doesnt focus close.