Segmentation by texture using correlation.

The correlation coefficients are used for segmentation according to texture. They are first evaluated on a set of square regions forming two levels of the quadratic picture tree (or pyramid). If the coefficients of a square and its four children in the tree are similar, then that region is considered to be of uniform texture. If not, it is replaced by its children. In this way, the split-and-merge algorithm is used to achieve a preliminary segmentation. It is followed by a grouping algorithm using the correlation coefficients and the region adjacency graph, plus a small region elimination step. The latter regions are grouped according to their gray level because texture cannot be defined reliably on very small regions. Examples of implementation on four pictures are included.