glop!
I'm sure that your picture is a jpeg .. the jpeg is very bad ( the worst ! ) for the sprites 'cause it cannot keep the black black
let me explain it : the jpeg save the images with some lost of quality, and this is your problem : the black is not black anymore, but grey very dark.
so, open your file with paint or an other programm, and paint the dark area in real dark : only dark, pure dark, 100% dark, as my friend, vador
and then, save it in bitmap file, because the bitmap wash the dark darker than the dark
(no, im not mad)
I'm following John, but I'm not john.
Lol, it is funnier in french