1. A system comprising: one or more processors; computer-readable media coupled to the one or more processors; a machine vision module, stored in the computer-readable media and executed by the one or more processors, configured to receive a scan of text, identify individual characters in the scan, and determine locations of centers of the individual characters; a geometry analysis module, stored in the computer-readable media and executed by the one or more processors, configured to determine center-to-center distances between the centers of the individual characters and displacement distances between the centers of individual characters and a reference location; a statistical analysis module configured to identify a representative value of center-to-center distances for the scan of text, to identify a representative value for the displacement distances of individual characters that start a line of text, and to identify a representative value for the displacement distances of individual characters that end a line of text; a character frame module configured to determine dimensions of a character frame for the characters in the scan based at least in part on the representative value of center-to-center distances; and a text block frame module configured to determine: (1) a start edge of a text block frame around at least a portion of the text in the scan based at least in part on the representative value for displacement distances of centers of individual characters at the start of lines of text and the dimensions of the character frame; and (2) an end edge of the text block frame based at least in part on the representative value for displacement distances of centers of individual characters at the end of lines of text and the dimensions of the character frame.