Method and system for creating a fused image from an image pair comprising a high resolution panchromatic image and lower resolution multi-spectral image. The method includes obtaining image data (204) defining a first image of a panchromatic image type and a second image of a multi-spectral image type. The first image has a first spatial resolution and a first spectral resolution. The second image has a second spatial resolution which is lower than the first spatial resolution and a second spectral resolution higher than the first spectral resolution. The method also includes a step (212) of concurrently calculating a point-spread function for down-sampling the first image to the second spatial resolution, and a set of weights for down-sampling the second image to the first spectral resolution.