Multiresolution-based image fusion with additive wavelet decomposition

The standard data fusion methods may not be satisfactory to merge a high-resolution panchromatic image and a low-resolution multispectral image because they can distort the spectral characteristics of the multispectral data. In this paper, we developed a technique, based on multiresolution wavelet decomposition, for the merging and data fusion of such images. The method presented here consists of adding the wavelet coefficients of the high-resolution image to the multispectral (lowresolution) data. We have studied several possibilities concluding that the method which produces the best results consists in adding the high order coefficients of the wavelet transform of the panchromatic image to the intensity component (defined as ) of the multispectral image. The method is, thus, an improvement on standard intensity-hue-saturation (IHS or LHS) mergers. We used the “à trous” algorithm which allows to use a dyadic wavelet to merge nondyadic data in a simple 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 mergers in preserving both spectral and spatial information.