[en] During 1974-77 the collaboration has collected more than 900 k events at the Serpukov accelerator using a phototaking system with a 5m long magnetic spark spectrometer. The aim of the experiment is the study of the diffraction dissociation of π and K mesons on different nuclei at 40 GeV/c. The major part of the events (that is 750 k events) has been processed at CNAF during 1977-79. As the events were recorded in two views, we handled more than 1.5 x 10⁶ pictures. The aim of the automatic system was the accurate measurements of spark coordinates, that were then analyzed by an off-line pattern recognition program. To guarantee a homogeneous quality of information to the pattern recognition program, we introduced suitable controls to check for good computation of fiducials and spark centres of gravity, together with distortion correction. (orig.)