The video in this article (http://gizmodo.com/) describes how scans are processed in software to extract readable text from a piece of charcoal that was once a Biblical scroll. They first determined the layers that represented the rolled up scroll. Because the ink was denser than the scroll skin the ink showed up as brighter pixels on the layers revealing characters.
The text was Leviticus -- now the oldest version found. Leviticus has such gems as "love your neighbor as yourself," but also "don't wear clothing made of two kinds of material" and many other things not to do. It also has a darker side when it was used to justify slavery.