Parameter estimation for multivariate gamma distributions

Determining similarity measures between two images is a interesting problem for image registration or change detection. Bivariate gamma distributions are good candidates for radar images since their marginals are known to be univariate gamma distributions. This paper addresses the problem of estimating the parameters of these bivariate gamma distributions by using the maximum likelihood method and the method of moments. The performances of both estimators are compared. Asymptotic expressions for the estimation variances are also derived.