The method comprises: providing a source image comprising a plurality of pixels, each pixel having a source value, providing an inverted threshold value for each pixel of the plurality of {HEAD ~ pixels}, and generating thereof a temporary image comprising a temporary value for each pixel of the plurality of {TAIL ~ pixels} 
The method comprises : providing a source image comprising a plurality of pixels , each pixel having a source value , providing an inverted threshold value for each pixel of the plurality of { HEAD ~ pixels } , and generating thereof a temporary image comprising a temporary value for each pixel of the plurality of { TAIL ~ pixels }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 TAIL TAIL TAIL TAIL TAIL