Final full-text version of the paper available at: http://www.sciencedirect.com/science/journal/00983004Measuring and storing magnetometer data recorded photographically is a difficult problem for a geomagnetic observatory. In the Ebre Observatory, to overcome the problem, we have developed a system using modern computing advances which include electronic scanning, storage on CD-ROM media, and image analysis. This paper describes the main processes performed by this system. In particular, it describes the main difficulties found in the process of digitization (intersections, gaps,…) and how they were solved.Authors thank the collaboration of the Juan Salañer Foundation and the C.E.T.S. of the Institut Químic de Sarrià, and recognize the contribution of J. Mustany and R. Gené, the true pioneers of this work.Peer reviewed