1. A method of creating a normalized representation of a symbol candidate appearing in a two-dimensional image field comprising the steps of: scanning the candidate in an ordered manner and assigning to the candidate a representation by coordinates along axes of a coordinate system, the coordinates corresponding to the line and position values relating to the scan signals generated by the candidate; determining the center of mass of the representation of the candidate; determining a point of the candidate at a maximal distance from its center of mass; scaling the candidate with respect to its center of mass by a factor proportional to the reciprocal of the distance from the center of mass to the point of maximum extremity; rotating the candidate around its center of mass so that the segment determined by its center of mass and the point of maximum extremity lies at a prescribed angular orientation with respect to the axes of the coordinate system; comparing the scaled rotated candidate to a library of stored representations of symbols and determining the one with which it has the greatest degree of overlap.