Another important perceptual dimension of the regions is their size in terms of area and spatial extent.
The distance in area between two regions is given by the absolute distance
The width and the height of the MBRs provide for useful comparison of region spatial extents. It is much simpler than shape information, which we do not utilize in the system, and provides excellent grounds for discriminating regions. The distance in MBR width (w) and height (h) between two regions is given by