In this article, we attack the problem of distinguishing textured images of
real surfaces using small samples. We first analyze experimental data that
results from applying ordinary Conditional Markov Fields. In the face of
the disappointing performance of these models we introduce random fields
with spatial interaction that is itself a random variable (usually
referred to as random fields in a random environment). For this class of
models, we establish the power spectrum and the autocorrelation function
as well defined quantities and we devise a scheme for the estimation
of related parameters. The new set of features that resulted from this
approach was applied to real images. Accurate discrimination was observed
even for boxes of size 16x16.