18. A computing device, comprising: at least one processor; a memory device including instructions operable to be executed by the at least one processor to perform a set of actions, configuring the at least one processor to: obtain an image of at least a portion of a document; identify a pattern of geometric characteristics in the portion of the document; and identify a source document that includes the portion based at least in part on the pattern of geometric characteristics; in which the geometric characteristics comprise one or more of word length, letter height, letter width, relative location of ascending characters, relative location of descending characters, sentence length, paragraph size and punctuation marks.
22. The computing device of claim 18 , in which the geometric characteristics comprise a classification of similarly shaped letters.