A Framelet-Based SFIM Method to Pan-Sharpen THEOS Imagery

This paper proposes an improved framelet-based pan-sharpening algorithm for Thailand Earth Observation System (THEOS) imagery to decrease the effects of different acquisition times between panchromatic (Pan) and multispectral (MS) images, in which the smoothing filter-based intensity modulation (SFIM) is introduced into low-frequency information fusion instead of the conventional "mean" rule. Moreover, a two-layer procedure is presented to reduce the impacts of mixed pixels caused by the large difference of spatial resolutions between the Pan and MS images. The proposed method is tested on two THEOS datasets and compared with the Gram-Schmidt, SFIM and traditional framelet-based methods. The portability across contourlet transform is also examined. Both qualitative and quantitative evaluation results demonstrate that the proposed method is more independent of the illumination of the Pan image and can achieve better spectral fidelity while maintaining spatial sharpness.