Why do many modern aircraft have wings and horizontal stabilizers in two-tone colors?

[guy_liking_pretty_planes]

If I were to own airplanes, I would specify that wings and horizontal stabilizers be painted in solid colors. Is there any technical aeronautical reason for mismatched paint colors?
As for vertical stabilizers, they don't have to be painted a solid color to suit my fancy.

 

[Mud Eagle]

Well, the slats are out in that pic, for one....creating that "black leading edge".