Many times we start our drawings in monochrome usually I try to lighten everything using the eraser but sometimes I lose track. This messed up the coloring process when it come down to it. I showed a few examples of what I mean. Basically, the tool will convert any value in the white channel into alpha transparency channel. Example: if RGBA is 125,125,125,0 convert to 0,0,0,125. Even if we have to convert our layer to gray scale first it would be worth it.