What i am trying to accomplish is taking a signature off of an image\photograph and matching its authenticity with an already proven signature of the individual. So say i have an image of someones signature on a contract. Now i want to be able to cross reference that signature with an image i have that is a verified signature from the person. What classes should i be looking into in order to accomplish this?

What im doing now is using linear algebra and comparing where there is a pixel shaded in or not. That should give me the exact positions on the image that the signature is written on. The only thing im seeing there would be trouble with is for 1 scaling of the signature and 2 taking the image off of a colored background say a postcard. The postcard would have many colors and i have to exclude them from the comparison.