Looking first at modification of the alpha value, for each pixel in the design image a modified alpha value for {HEAD ~ that pixel} is calculated based on the value of {TAIL ~ MIN} and the original alpha of the pixel as follows: 
Looking first at modification of the alpha value , for each pixel in the design image a modified alpha value for { HEAD ~ that pixel } is calculated based on the value of { TAIL ~ MIN } and the original alpha of the pixel as follows :
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 HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH