Statistical Unmixing of SAR Images

A method is presented which uses logarithmic statistics to detect and characterise class mixtures and targets in background clutter in synthetic aperture radar (SAR) images. Mixtures of ground cover types show up as extreme radar texture in statistical analysis of SAR images. Instead of modelling this as a spatially nonstationary radar cross section, this paper demonstrates how a mixture model analysis can be used to characterise the separate components and estimate their mixing proportions. 1 Theory 1.1 Mixture Model Let X be a real and positive random variate which represents a measurement obtained within a certain region of a SAR image. It is assumed that the region of interest is heterogeneous, and that X can be modelled with a twocomponent mixture model. This means that the observation X will be drawn from a distribution with probability density function (pdf) pX1(x) with probability π1, or from a distribution with pdf pX2(x) with probability π2. The pdfs are distinct, meaning that pX1(x) 6= pX2(x), and the mixing proportions obey