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