Art galleries must tackle this issue all the time.Photo's of works of art are normally seen all over the place.
One of the things to check is the software that can link with the camera. Canon for instance has the EOS utility which can connect to the camera and control it from the software on the computer.
For a true 'scan' type image there will be a need for optical correction, the longer the focal length of the lens the less correction is needed. I'm pretty sure the Canon software (Digital Photo Professional
) that comes on a disk with a camera, will correct both distortion and vignetting
As well as the camera working out a good workflow will help the resulting image accuracy.