In the present inventive method, individual traces of seismic data are migrated (41) without any assembling of different midpoints or any summing of different offsets, so that post-migration processing or analysis, e.g. trace alignment, may be applied to the individual migrated traces (42) to compensate for any deficiencies among them, before stack and assembly. Thus, the present invention fully separates the steps of migration (41), assembly (43), and stacking (44), which are combined together in traditional migration. Thus, imaging deficiencies can be measured and addressed in the image space before they are obscured by summation. Afterward, summation can proceed to construct the improved final image (45).