1. A method which, while preparing data for comparison methods that compare the cartridge cases fired from firearms and compute similarity values, segments cartridge case bases by using surface height matrices for selection of the best appropriate mark regions to be used in similarity computation, characterized by the following steps which aim at detection of the primer circle ( 28 ), primer pocket gap circle ( 29 ) and cartridge case base circle ( 27 ): a) Gradient magnitude values are found for each element on the surface height matrix ( 5 ) that covers all of the cartridge case base ( 1 ) region and a new matrix is formed by locating these gradient magnitude values in such a way that they correspond to the coordinates of each element on the surface height matrix ( 5 ), b) Coordinates of the center of the cartridge case base are detected by using the Hough transformation, preferably 2 Stage Hough Transform (21HT) method, on the matrix formed in a), c) The cartridge case base surface height matrix according to the cartridge case base central coordinates detected is transformed into polar coordinates and a polar height matrix is obtained, d) On the polar height matrix, for each radius value, all data corresponding to that radius value are selected and the mean of them is calculated, e) With the calculated mean values as a function of radius, a one-dimensional signal, called ‘Average Height Signal on the Basis of Radius’ (AHSBR), is formed. The x-axis of the signal shows the radius value and the y-axis shows the average height value of the radius, f) By using the signal similarity analysis conducted on this AHSBR on the basis of the step model 1 ( 33 ) and/or step model 2 ( 34 ) and/or step model 3 ( 35 ), the primer circle ( 28 ), primer pocket gap circle ( 29 ) and cartridge case base circle ( 27 ) are detected.