Abstract: An image fusion algorithm based on the nonsubsampled Contourlet transform （NSCT） is proposed by analyzing the design and implementation of the filter bands of the NSCT.By the algorithm,firstly,multiscale decomposition of the source images is performed with nonsubsampled Laplacian pyramid.Directional decomposition of the high-frequency subbands in every scale is also made with nonsubsampled directional filter bands.Multiscale decomposition and directional decomposition constitute the NSCT.And then, the NSCT coefficients for the fused image can be obtained by means of the fusion rule based on region energy.Finally,the fused image is reconstructed by inverse NSCT.Experimental results show that the method presented in the paper works better than the à trous wavelet transform and the Mallat wavelet transform.