I took some photos of a document with my iphone. Everything is perfect except the colors, the certificate looks great in the middle, but on the side it looks dark, darkness increasing spherically towards outside, the camera points directly towards the center of the page when photo is taken.
I tried maxing out the brightness and contrast in gimp, until a level so that I can atleast read the important part. This removed the darkness, but it made the text in middle also very light. How can I remove the darkness as well as prevent the text from becoming very light?