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