In a digital image registration method, a second digital image is transformed to be more like a first digital image using a modification function, resulting in a modified second digital image. A set of first features of each of the first and modified second digital images is determined. Zones are specified in each of the first and modified second digital images. A set of zonal features, of each of the zones is determined. Compound mutual information is computed from the first and zonal features. The modification function is altered. The transforming, determining, specifying, determining, computing, and altering are iterated until the compound mutual information is maximized.