Recent developments in modeling image discrimination by feature analytic and frequency selective methods are discussed. Some issues relating to the design of two-dimensional spatial frequency filters are developed within the context of two experiments on texture discrimination using artificial and naturally occurring textures. Results of these experiments indicate that, given an adequately formulated relationship between spatial frequency and orientation tuning parameters of the filter, one can predict a variety of texture discriminations using only amplitude-specific models. Finally, guidelines are established for ascertaining when phase transmission characteristics do become critical in two-dimensional image processing by the human observer.