A multifocus image fusion in nonsubsampled contourlet domain with variational fusion strategy

Based on the variational idea, we propose a new fusion strategy for nonsubsampled contourlet transform (NSCT). For NSCT bandpass subband coefficients of input images, we take the main component of coefficients as the target and then build an extremum problem for energy functional to find the closest to the target one as the fused coefficient. We apply the gradient descent flow to minimize the functional and give the numerical scheme. The experimental results show that the proposed strategy outperforms state-of-the-art image fusion strategies for NSCT in terms of both visual quality and objective evaluation criteria.