Abstract: We described a procedure for quick processing images of electrode spots of an oscillatory and unipolar spark discharge onto a flat surface of an iron electrode in an air atmosphere. The images were taken using an interference microscope—surface analyzer NewView 5010. The crater diameters were measured using a program for measuring the size of nanopowder particles. A comparative statistical analysis of diameter distributions was carried out using sample comparison tests and analysis of variance included in the Excel package. The factors were the discharge energy and kind of experiment (cathode, anode, oscillatory discharge). It is shown that the characteristics of the distribution of crater diameters weakly depend on the capacitor energy. At the same time, they depend very significantly on the experimental kind. The maximum heights and depths of the relief in the case of an oscillatory discharge are several times higher than their values for a unipolar discharge. © Pleiades Publishing, Ltd. 2023. ISSN 1062-8738, Bulletin of the Russian Academy of Sciences: Physics, 2023, Vol. 87, Suppl. 2, pp. S274–S280. Pleiades Publishing, Ltd., 2023.