Multifocus image fusion using the nonsubsampled contourlet transform

A novel image fusion algorithm based on the nonsubsampled contourlet transform (NSCT) is proposed in this paper, aiming at solving the fusion problem of multifocus images. The selection principles of different subband coefficients obtained by the NSCT decomposition are discussed in detail. Based on the directional vector normal, a ‘selecting’ scheme combined with the ‘averaging’ scheme is presented for the lowpass subband coefficients. Based on the directional bandlimited contrast and the directional vector standard deviation, a selection principle is put forward for the bandpass directional subband coefficients. Experimental results demonstrate that the proposed algorithm cannot only extract more important visual information from source images, but also effectively avoid the introduction of artificial information. It significantly outperforms the traditional discrete wavelet transform-based and the discrete wavelet frame transform-based image fusion methods in terms of both visual quality and objective evaluation, especially when the source images are not perfectly registered.