On the contrast topic: adaptive thresholding can be very helpful (I believe Bradley Local Thresholding was one I had particular success with) however most of these algorithms work in a grayscale domain which means they are dependent upon which color->grayscale transformation is used[1]. I spent a long time researching full color algorithms but never got to a truly successful end result with them. And even if you get a good image with huge contrast you still will end up with the actual light/dark transition looking like an edge.
On 3D deformation, you're officially in academic research land. Nearly all algorithms require you to have a solid guess as to what the aspect ratio of the target object is. Other algorithms use heuristics based upon what you expect to find on a page. One particularly fun algorithm used the baseline of text (I believe for that paper it was Arabic) and fit a high-order curve to it which was then reversed. Unfortunately I haven't seen a truly generic approach that doesn't require a implementation-specific input.
[1] Frankly my feeling is that RGB to grayscale is a mistake and holding back many of these algorithms