If you have a digital camera you already have a basic scanner, except photographs from your camera just doesn’t look like a scanned copy. The problem with using a camera as a scanner is perspective.
Perspective is a great thing when you know how to use it to your advantage. Photographers and digital artists love to toy with perspective to produce astonishing optical illusions like tilt-shift and 3D. But when scanning documents, perspective is the ultimate spoilsport. Perspective makes photos of documents look skewed - get too close to the document, and the camera will produce a fish-eye like effect; get too far, and the photo will appear dark because the light from your camera flash cannot illuminate the scene/document enough.