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