1. A system for determining an image resolution of a document image, comprising: at least one computer system, including: an extracting system for extracting a magnetic ink code recognition (MICR) code line from the document image, wherein the extracting system provides coordinate values for each of a plurality of MICR characters in the MICR code line; a calculating system for calculating a set of resolution values based on the coordinate values of the MICR characters and a known spatial characteristic of a MICR character set; and a statistical analysis system that calculates a representative resolution value from the set of resolution values, wherein the representative resolution value is given as a number of pixels per unit length.