For {TAIL ~ each image} in a database of {HEAD ~ images} having known regions of interest, global image features are measured and an image characteristic index is established based on these global image features 
For { TAIL ~ each image } in a database of { HEAD ~ images } having known regions of interest , global image features are measured and an image characteristic index is established based on these global image features
OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH