The dection of a pencil erasure
[To see these images at higher resolution, please click on each photo]
In this series of comparisons stands out the usefulness of the high resolution digital scanning of an exhibit. The case was about a pencil-written signature, with an interruption in the B's final area. Image acquisition with non-digital methods or with digital but low resolution scanning (photo 1)
could not allow the comprehension of what had happened in the signature's final part. Instead, through high resolution scanning it was possible to demonstrate (with the help of appropriate image enhancement algorithms) that the pencil line interruption was not caused by an accidental event; rather, it was brought about by the intervention of a hand-held pencil eraser (clearly with the aim of voluntarily hiding that short area of the signature).
In the computer enhanced images (photos 2, 3 and 4) now it is possible to see distinctly the tiny black-lead residues left over above and below the erased area; these are the signs and effects of the eraser's up and down repeated movements along the paper.