Images A multi-spectral image is a collection of several monochrome images of the same scene, each of them taken with a different sensor. Each image is referred to as a band . In image processing, multi-spectral images are most commonly used for Remote Sensing applications.
Satellites usually take several images from frequency bands in the visual and non-visual range.
For example, a multi-spectral image can be edge detected by finding the edges in each band and than ORing the three edge images together. However, we would obtain more reliable edges, if we associate a pixel with an edge based on its properties in all three bands and not only in one. To fully exploit the additional information which is contained in the multiple bands, we should consider the images as one multi-spectral image rather than as a set of monochrome graylevel images. For an image with k bands, we can then describe the brightness of each pixel as a point in a k -dimensional space represented by a vector of length k . Special techniques exist to process multi-spectral images.