Based on Nonsubsampled Contourlet Transform(NSCT),human visual relative contrast sensitivity function(RCSF) and absolute contrast sensitivity function(ACSF) are proposed firstly.Then a remote sensing image fusion algorithm(IFA_CSF) based on human visual contrast sensitivity function(CSF) is proposed.The IFA_CSF adopts NSCT as the muti-scale transformation tool.The single direction high frequency subband is fused by ACSF and multi-direction high frequency subband is fused by RCSF.Meanwhile the high frequency...