Scientists at HP have demonstrated a technique for using ordinary, unmodified flatbed scanners to scan an image and then detect and correct defects such as creases.
On the surface, the technique appears relatively simple. Most flatbed scanners use two separate light bulbs to accurately capture all the colour in a photo. By controlling these independently of each other, two slightly different images (each taken from different directions as the bulbs move under the photo) can be captured of the same photograph. From these, rudimentary 3D information can be generated.
With the defect — a crease in our example — identified, software can artificially mask it entirely. Known as ‘infilling’, each pixel inside the scanned crease is replaced by a new one generated from pixels just outside of the crease. The software makes sure the two pixels are similar, to avoid sticking a giant red pixel in the middle of a bunch of green ones.
The main limitation is that it requires a 3D defect, defects that lie perfectly against the glass can’t be detected by the different lights.
via HP restores creased photos with flatbed scanners – Crave at CNET UK.
