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