Multi-focus image fusion based on nonsubsampled contourlet transform and focused regions detection

A novel multi-focus image fusion algorithm is proposed in nonsubsampled contourlet transform (NSCT) domain. It uses the technique of focused regions detection and some new fusion rules to guide coefficients combination. At first, the initial fused image is acquired with one of conventional multiresolution image fusion method; meanwhile the source multi-focus images are decomposed by using NSCT. The pixels of the original images, which are more similar to the corresponding pixels of initial fused image, are considered from the sharply focused regions. Based on this, the initial focused regions can be determined and the morphological opening and closing are employed for postprocessing. Then the focused regions in each image are identified and used to guide the different subband coefficients combination. Moreover, in order to avoid the erroneous results introduced at the boundary of the focused regions, the coefficients located at the focused border regions are fused by the choice of corresponding subband coefficients according to some new fusion rules. Finally, the fused image is reconstructed by performing the inverse NSCT. The experimental results show that the proposed fusion approach is effective and can provide better performance in fusing multi-focus images than some current methods.