{HEAD ~ The process} of generating the temporary value may further comprise in all alternatives: smoothing the intermediate value for each pixel; and in the third and fourth alternatives: smoothing {TAIL ~ the first difference value} and the first minimum value 
{ HEAD ~ The process } of generating the temporary value may further comprise in all alternatives : smoothing the intermediate value for each pixel ; and in the third and fourth alternatives : smoothing { TAIL ~ the first difference value } and the first minimum value
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH