In DEXA (dual energy x-ray absorptiometry), a system for automatically or nearly so identifying a region of interest in an AP (anterior/posterior) spinal image by processing the pixel values within a global region to find the lateral extent of the vertebra and the spaces between vertebra, and further processing the pixel values within the region of interest to derive estimates of bone parameters. In addition, also in DEXA, a system for automatically locating regions of interest in the hip.