Seismic imaging is carried out by backward extrapolation (migration) of the wavefield from the<br>observation surface to the geologic media. The quality of images depends on the accuracy of the wavefield<br>reconstruction at interior subsurface points. “True amplitude migration” algorithms pretend to be accurate but<br>are computationally expensive. The increased expense is not always justified by improvement of the final<br>image. An explanation can be seen in that a high level noise is produced by the migration algorithms<br>themselves. One of the components of noise is diffraction caused by limitation of migration aperture.<br>Reasonable choice of aperture shape and dimensions converts diffractions into useful information thus<br>improving images.