Implementation of Hyperspectral Image Unmixing via Alternating Projected Subgradients

An imaging spectrometer is an instrument that captures a continuous spectrum of light (often ranging from 460nm to 2.5μm) for every pixel in a photograph. Using this type of instrument an image can be taken of any subject and detailed spectral analysis can be run on any part of the image produced. Hyperpectral image umixming is the process by which hyperspectral images are broken down into their most basic parts. This is a key aspect of hyperspectral imaging, allowing a complex spectrum produced by a single pixel to be decomposed into a set of basis spectrums. The basis spectrum when linearly combined make up the spectrum observed in that pixel. This set of basis spectrum can then be easily compared to a known spectrum library to determine the composition of that pixel. This particular technique is extremely useful when the image is of unknown composition.