A broad research program under the direction of USAECOM is in progress to investigate techniques and equipment characteristics suitable for automatically processing graphical data for military requirements. This paper considers a phase of this program, which is concerned with techniques and experimental test results designed to determine machine proficiency for automatic recognition and classification of military map symbols. For convenience of test, these map symbols are on glass slides, but the implication is that the technique is useful for automatically categorizing and symbolically recording any form of graphical data that can be displayed electrically or recorded on hard copy. Preprocessing methods used to reduce the complexity of the input data so that it can be more readily handled by the adaptive section of the machine are discussed. A description of the preprocessing technique is given.