Multiresolution-based image fusion with additive wavelet decomposition

The standard data fusion methods may not be satisfactory to merge a high-re solution panchromatic image and a low-resolution multispectral image becaus e they can distort the spectral characteristics of the multispectral data. In this paper, we developed a technique, based on multiresolution wavelet d ecomposition, for the merging and data fusion of such images. The method pr esented here consists of adding the wavelet coefficients of the high-resolu tion image to the multispectral (low-resolution) data. We have studied seve ral possibilities concluding that the method which produces the best result s consists in adding the high order coefficients of the wavelet transform o f the panchromatic image to the intensity component (defined as L = R+G+B/3 ) of the multispectral image. The method is, thus, an improvement on standa rd intensity-hue-saturation (IHS or LHS) mergers. We used the "a trous" alg orithm which allows to use a dyadic wavelet to merge nondyadic data in a si mple and efficient scheme. We used the method to merge SPOT and LANDSAT (TM ) images. The technique presented is clearly better than the IHS and LHS me rgers in preserving both spectral and spatial information.