{HEAD ~ The modified pixel color} is calculated by subtracting the level of {TAIL ~ gray} in the original pixel color from each of the three original component color values and increasing any remaining color component values as a function of the modified alpha value of the pixel 
{ HEAD ~ The modified pixel color } is calculated by subtracting the level of { TAIL ~ gray } in the original pixel color from each of the three original component color values and increasing any remaining color component values as a function of the modified alpha value of the pixel
HEAD HEAD 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH