Systems are presented for the extraction of simple topological codes for loop, whorl, and arch pattern types. The generated codes take the form of vectors or simple digital arrays. The nature and frequency of changes that may occur in such codes is investigated; fingerprint comparison algorithms, based on these topological codes are developed. The objective of the algorithms is to draw a score derived from the degree of nearness of the codes that reflects the similarity or dissimilarity of the two prints being compared. A detailed analysis of the performance of such algorithms is given, making extensive use of results of investigation into the match and mismatch score distributions produced by each one. A final test is described in which the most effective topologically based algorithm is tested directly against one of the best existing spatial algorithms. Results indicate that topology-based coding, with the inclusion of crude distance measures, is an extremely accurate and efficient basis for the comparison of rolled impressions. Figures, graphs, tables, and 5 references. (Author abstract modified)