I tried to create a feathered sphere as a texture by creating a quadratic sphere and overlaying it with simple clouds.
Here what I get in Gimp (and what I expect):
And here what I get when I try to re-create the result as a Blender procedural texture:
I have attached the blend and gimp files:
overlay.zip (142 KB)
Now the question: Is the overlay mode implemented differently in Blender? Or could this be a bug?