I made a quick explaining picture for you:
As you can see, this applies even in the real world.
Even the darkest contour of my hand is not truly black.
Jalis: Freelancer, you're a duck | Sachi: Freelancer, you're a duck | Reanimator: Freelancer, you're a duck
satiknee: Freelancer, you're a duck | Wiggi: Freelancer, you're a duck | Tarlan: Freelancer, you're a duck