Comparison of different BCS schemes: In (a), we show the reconstruction error vs reconstruction time for the proposed BCS, alternate BCS, and the greedy BCS schemes. The free parameters of all the schemes were optimized to yield the lowest possible errors, while the dictionary sizes of all methods were fixed to 45 atoms. We plot the reconstruction error as a function of the CPU run time for the different schemes with different dictionary initializations. The proposed BCS and alternating BCS scheme converged to the same solution irrespective of the initialization. However, the proposed scheme is observed to be considerably faster; note that the alternating scheme takes around ten times more time to converge. It is also seen that the greedy BCS scheme converged to different solutions with different initializations, indicating the dependence of these schemes on local minima.