Pan-sharpening of Multispectral Images: A Critical Review and Comparison

This paper critically reviews state-of-the-art and advanced methods for multispectral (MS) and panchromatic (Pan) image fusion based on either intensity-hue-saturation (IHS) transformation. or redundant multiresolution analysis (MRA). In either cases. lower-resolution MS hands are sharpened by injecting details taken from the higher-resolution Pan image. Crucial point is modeling the relationships between detail coefficients of a generic MS band and the Pan image at the same resolution. Once calculated at the coarser resolution, where both types of data are available, such a model shall be extended to the finer resolution to weight the Pan details to he injected. Two injection models embedded in an "a trous" wavelet decomposition will be compared on a test set of very high resolution QuickBird MS+Pan data. One works on approximations and provides a partial unmixing of coarse MS pixels via high-resolution Pan. Another is based on spectral fidelity of original and merged MS data. Fusion comparisons on spatially degraded data, whose highresolution MS originals are available for reference, show that the former performs better than the latter, in terms of both spatial and spectral fidelity.