The primary inducement for organizing an international Conference on 'Image Processing Techniques in_Astronomy' was the fact that the recording microdensitometer VAMP ('Vol Automatische Micro Photometer') of the Utrecht Astronomical Institute was operative for a few years. The necessity of comparing the in- strument and its performance with similar instruments nowadays available at many other institutes, was stimulating enough to organize a meeting on the above subject. It took place in Utrecht on March 25, 26 and 27, 1975. The Scientific Organizing Committee consisted of J. Borgman (Groningen), R.B. Dunn (Sacramento Peak), H. Elsasser (Heidelberg), L.D. de Feiter, T. de Groot, J.R.W. Heintze, C. de Jager, H. Nieuwenhuijzen (Utrecht) and W. Wiskott (Geneve). About 175 scientists from 14 countries participated in the meeting which appeared to be successful and offered a good opportunity of exchanging information and comparing experiences. The VAMP was bought with financial support of the Utrecht University and the Netherlands Foundation for Scientific Research (Z.W.O.). The conference was organized with financial support from The Netherlands Ministry of Science and Education, The European Southern Observatory, The Leids Kerkhoven-Bosscha Fonds, The Astronomical Institute of Utrecht, to which Institutes and Organisations we express our sincere gratitude. C. de Jager H. Nieuwenhuijzen editors PAR T WHAT INFORMATION DO WE NEED, FOR WHICH ASTRONOMICAL PROBLEM? ASTROMETRY K. Aa. Strand U. S. Naval Observatory Washington, D. C, INTRODUCTION Considerable progress has taken place in astrometry over the past two decades.