1. A method for recognizing characters in a portable terminal with a scan module, comprising the steps of: generating scanned image data by the scan module by scanning a scan target through a scanning-light input/output panel provided on an external surface of the portable terminal as the portable terminal moves across the scan target; deleting part of the scanned image data when a current moving speed of the portable terminal is less than a lower limit of an optimal scan speed range, and performing character recognition on remaining scanned image data; and detecting image data most similar to the scanned image data from a previously stored correction image database when the current moving speed is greater than an upper limit of the optimal scan speed range, and outputting characters corresponding to the detected image data as character recognition results.