Fig. 1.

Schematic diagram of the proposed method. Two novel strategies (edge sparse estimation and iterative reweighting) were proposed to accurately estimate the source extent. The edge sparse estimation is based on the prior information that source is densely distributed but the source edge is sparse. The source extent can thus be obtained by adding the edge-sparse term into the source optimization solution. The iterative reweighting is based on a multistep approach. Initially an estimate of the underlying source is obtained. Consequently the locations which have less activity (smaller dipole amplitude) are penalized based on the solutions obtained in previous iterations. This process is continued until a focal solution is obtained with clear edges.