Additive integration of SAR features into multispectral SPOT images by means of the à trous wavelet decomposition

This paper aims to describe a method for integrating the Synthetic Aperture Radar (SAR) features into multispectral (XS) images using conjointly the modified Brovey transform (MBT) and the à trous wavelet decomposition (ATWD). The MBT is based on the intensity-hue-saturation (IHS) fusion method, which allows modulating locally each XS image by the ratio of the new intensity component and the initial intensity component in order to produce the new XS-SAR images. The ATWD allows extracting features from the SAR image in order to integrate through an additive procedure into the initial intensity component. The resultant new intensity component is then used for producing new XS-SAR images. In order to control the amount of SAR features to be integrated into XS images, a normalized importance measure is derived from the wavelet coefficients for selecting the significant SAR features according an adjustable threshold. SPOT-XS and RADARSAT-SAR images covering a region of Vietnam are used to evaluate visually and statistically the effect of the proposed method, in particular other existing methods in terms of spectral preservation and amount of SAR features integrated into XS images.