Multitemporal and multisensor analyses of satellite images are becoming important research fields in Geo-information sciences. This is mainly due to the large amount of remotely sensed data accumulated in the last twenty-five years. We are also waiting for even more information to come from a great number of new and powerful Earth observation systems. Improvements on spatial and spectral resolution mean more gigabyte for a computer to manipulate. Hence, in order to explore all this sources of information, effective ways of fusing, analysing and storing this huge amount of data must be developed. Wavelet analysis provides a basis for handling multiresolution data sets, for understanding noisy signals and for improving storage efficiency. The technique is already recognised for remote sensing applications such as automatic image registration, image fusion, feature extraction, speckle reduction and texture classification. Change detection techniques based on multi-resolution analysis have been studied.

• Carvalho, L.M.T.; Fonseca, L.M.G.; Murtagh, F.; Clevers, J. G. P. W. “ Digital change detection with the aid of multiresolution wavelet analysis”, International Journal of Remote Sensing, 22 (18), 3871-3876, Dec. 2001.
• Carvalho, L.M.T.; Fonseca, L.M.G.; Murtagh, F.; Clevers, J.G.P.W. “Analysis of Changes at Multiple Spatial Scales”, 'International Archives of Photogrammetry and Remote Sensing' , vol XXXIII, part B7/1, commission VII, pp. 340-346. 2000