This paper presents a new algorithm for partitioning a gray-level imag
e into connected homogeneous regions. The novelty of this algorithm li
es in the fact that, by constructing a minimum spanning tree represent
ation of a gray-level image, it reduces a region partitioning problem
to a minimum spanning tree partitioning problem, and hence reduces the
computational complexity of the region partitioning problem. The tree
-partitioning algorithm, in essence, partitions a minimum spanning tre
e into subtrees, representing different homogeneous regions, by minimi
zing the sum of variations of gray levels over all subtrees under the
constraints that each subtree should have at least a specified number
of nodes, and two adjacent subtrees should have significantly differen
t average gray-levels. Two (faster) heuristic implementations are also
given for large-scale region partitioning problems. Test results have
shown that the segmentation results are satisfactory and insensitive
to noise.