Conclusion and Discussion

We introduce the self-adaptive approach for choosing a set of reference velocities. The approach is quite flexible and of little calculation cost. It can be used for general image edge-detecting also. Numerical tests demenstrate that the method is effective.

During the wavefield extrapolation, the wavefield merging remains a problem in the case of severe lateral velocity variation. Furthermore, by considering the velocity variance in a region, a better reference velocity choice can be reached.