{HEAD ~ The modified alpha value} and the modified color of a pixel are determined as {TAIL ~ a function} of the amount of gray in the original color of the pixel 
are determined as
{ HEAD ~ The modified alpha value } and the modified color of a pixel are determined as { TAIL ~ a function } of the amount of gray in the original color of the pixel
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH