Based on the analysis,a new stage by stage image fusion method based on the image content is put forward.This method using the spread characteristic of PCNN pulse and relation between its' ignition frequency and the frequency mapped to original images adaptively divides the original images into a few sets according to their gray figures;then organizes these sets according to needs of image fusion and makes every sets fuse with post-layer fused image gradually.This way can reveal the content and details of i...