Examples of radial surface mass density profiles of ringed galaxies. The first column shows the face-on projection of a galaxy with an inner ring (top row), an outer ring (middle row), and i+o rings (bottom row). The polar mesh that defines the azimuthal sections where the radial profiles are calculated is also displayed. These profiles are presented in the middle column, identified with the color that denotes their sections in the grid, and are shifted along the y-axis. The global profiles of the ringed galaxy and its control group are represented by solid and dashed black lines. The right column displays the derivatives of the profiles, approximated by forward finite differences.