Abstract: The directionlets based on digital segments and integer grids theory can not only inherit the characteristics of dimension-dependable wavelets, but also obtain the flexible multi directional characteristic by changing the directions of transform and sequences. A novel fusion method for panchromatic and multispectral images based on directionlets trans- form(DT) and PCA was presented. Firstly,a linear principle component analysis(PCA) was performed on the multi- spectral images to extract its first principle component, then we used DT to extract the spatial detail information of high-resolution panchromatic image. Therefore, the fused image can carry more spatial and spectral information. Experi- mental results show the new fusion method has a better performance, such as universal image quality index(UIQI)，u- nidue score index Q4 and average gradient, than wavelet based methods.

Key words: Image fusion, Panchromatic image, Mutispectral images, Directionlets