Comparison of Pansharpening Algorithms for Combining Radar and Multispectral Data

Iconic image fusion is a technique that is used to combine the spatial structure of a high resolution panchromatic image with the spectral information of a lower resolution multispectral image to produce a high resolution multispectral image. This process is often referred to as pansharpening. In this study, image data of the new RADAR satellite TerraSAR-X are used to sharpen optical multispectral data. To produce these images, use is made of the Ehlers fusion, a fusion technique that is developed for preserving maximum spectral information. The Ehlers Fusion is modified to integrate radar data with optical data. The results of the modified Ehlers fusion are compared with those of other standard fusion techniques such as Brovey, Principal Component, and with recently developed fusion techniques such as Gram-Schmidt, UNB, wavelet based fusion and CN-Spectral Sharpening. The evaluation is based on the verification of the preservation of spectral characteristics and the improvement of the spatial resolution. The results show that most of the fusion methods are not capable to integrate TerraSAR-X data into multispectral data without color distortions. The result is confirmed by statistical analysis.