1. In the processing of scanned images for character recognition, a method for isolating areas of the scanned medium for recognition processing comprising the steps of: storing representations of said scanned images in a memory; scanning said memory in a first direction so as to detect the end of a packet of data in said memory; sensing the location of said end of said packet in said memory; back-scanning said memory through said packet in a second direction, opposite to said first direction so as to detect the end of said packet in said second direction; recording the extent of said packet in memory in the direction perpendicular to said first and second directions during said back-scanning; sensing the location of the end of said packet in said second direction; whereby data in memory is isolated which can be removed to recognition processing.