This problem is not yet defined. To make some comparison, you need to define comparison criteria. There is such mathematical concept as
norm, a map that assigns lengths to vectors in the normed vector space, see
http://en.wikipedia.org/wiki/Norm[
^].
The problem is defined is you define some norm in the space of gray-scale pixel images. Don't tell me there is a natural norm which is assumed. There are different ways of calculating the difference between images.
Main directions in programming this thing would be using
System.Drawing.Imaging
. You can load two Bitmaps, instances of the class
System.Drawing.Bitmap
from files and use the method
System.Drawing.Bitmap.LockBits
with
System.Runtime.InteropServices.Marshal
to get access to the array of bitmap bits, so you could apply your algorithm of comparison.
See this code sample:
http://msdn.microsoft.com/en-us/library/5ey6h79d.aspx[
^].
—SA