Digital cameras and copies of handwritten documents

I am in the process of photographing all the copies that I have from documents and papers from Jan Glete, the Nationaal Archief, Carl Stapel, and Eric Ruijssenaars (from the Nationaal Archief). One that that I have found is that copies are generally high resolution and contain information that is not visible when looking at the paper. I have a 6.2 megapixel camera, and photographs of copies have some interesting properties. I have copies of handwritten notes from Jan Glete that were done in pencil. I found that when I have a high resolution image that I can enhance the picture digitally, so that the missing pieces are visible. They were not totally missing, but were very light on the copy. There are also copies that I received from Carl Stapel that have dark spots on them. In this case, I can adjust the image so that I can read the writing obscured by the dark spot. The trick in both cases is to adjust both brightness and contrast. If I were using a different graphics editor, I would be able to adjust intensity, as well. For the copies of pencil notes, I reduce brightness and contrast.