A separate three-dimensional (3D) integration filter mask if precomputed for each of x, y, and z dimensions with a given operator length. A portion of a 3D post-stack seismic data set is received for processing and loaded into a generated 3D-sub-cube. The separate 3D integration filter masks are applied to the loaded 3D-sub-cube to generate filtered 3D-sub-cube data. The square mean of the 3D-sub-cube is calculated to generate smoothed 3D-sub-cube data.