We present an unsupervised segmentation algorithm which uses Markov
Random Field models for color textures. These models characterize a
texture in terms of spatial interaction within each color plane and
interaction between different color planes. The models are used by a
segmentation algorithm based on agglomerative hierarchical clustering.
At the heart of agglomerative clustering is a stepwise optimal merging
process that at each iteration maximizes a global performance functional
based on the conditional pseudolikelihood of the image. A test for
stopping the clustering is applied based on rapid changes in the
pseudolikelihood. We provide experimental results that illustrate the
advantages of using color texture models and that demonstrate the
performance of the segmentation algorithm on color images of natural
scenes. Most of the processing during segmentation is local making the
algorithm amenable to high performance parallel implementation.