An improved imaging method for extended targets

When we use direct imaging methods for solving inverse scattering problems, we observe artificial lines which make it hard to determine the shape of targets. We propose a signal space test to study the cause of the artificial lines and we use multiple frequency data to reduce the effect from them. Finally, we use the active contour without edges (ACWE) method to further improve the imaging results. The final reconstruction is accurate and robust. The computational cost is lower than iterative imaging methods which need to solve the forward problem in each iteration.