Energy Reassignment of an Image for Improved Picking of Velocity Dispersion Curves

Many algorithms have been proposed to improve the resolution of the velocity dispersion curve through the use of different transforms to the frequency-velocity domain. The reassignment proposed in this paper is an image processing and picking technique that has the ability to overcome problems intrinsic to poor sampling and complex modal structure. We use an iterative approach in applying energy reassignment to move energy points closer to the crest of the dispersive mode in the frequency-velocity image. In this sense, energy reassignment of the image can be used as a mode separation technique. Directly reassigning the image is also computationally efficient, thus facilitating interactive analysis and processing of surface waves. An example from within the processing flow of a surface wave mitigation algorithm is given to show the advantage in using this process on beamformed dispersive modes.