Different images of the same object or region resulting from different sensors will include within themselves features associated with the used sensor.  

Image fusion means combining these separate  images into a single image which also incorporates all the features and properties of these images.

Fusion of electro-optic and SAR images, fusion of electro-optic and thermal images are the leading image fusions. Obtaining a high-resolution (Pan sharp) image with the fusion of pan image with MS image can also be considered as image fusion. Simultaneous expolitation support can be provided by combining EO/IR satellite images with the SAR image.

Using satellite images and aerial photos, a high-spatial and spectral image is obtained by making a fusion of high spatial resolution single band panchromatic image with the lower spatial resolution multispectral MS image.