The NSP (multi-scale decomposition method) of the traditional NSCT (non-subsampled contourlet transform) algorithm has a poor detail information capturing ability and when applied to image fusion it causes a loss of image details. In this paper

we present an improved NSCT algorithm. Different from the traditional NSCT algorithm

we adopt the non-subsampled morphological wavelet decomposition

which has a better detail capture capability

to realize a multi-scale decomposition of the source image and replacing the NSP decomposition. The source images are decomposed into four parts: low-frequency

horizontal high-frequency

vertical high-frequency

and diagonal high-frequency. Afterwards

the improved NSCT decomposition on high frequencies using the NDFB (non-subsampled directional filter) for multiple directions of decomposition is realized. Our experiments show that

compared with traditional algorithms

this algorithm has a better detail capturing ability

its image fusion effect is better under the same fusion rules

and all fusion indexes are improved. Among them

the average gradient is increased by 10%. This effective image fusion algorithm can be easily realized and widely used in multi-resolution image fusion.