Changing icons (using Nova launcher)

[Nicktyelor]

I'm themeing my phone based on this video for the Galaxy Nexus. Everything has gone fine, until now, when I'm trying to change the icons. It get an annoying black border around the icons I download from metro station (the recommended icon pack). In the video, the background doesn't show, and just the white icon displays. You can see what I mean in the picture below. Can anyone help me here? How can I get rid of this? Do I need to edit the icon pictures? Or follow a different route when I have to select "edit icon" or settings etc. ?
View attachment 51986

 

[nubby]

Did you expand the icon to the largest before you cropped?

 

[Garemlin]

Are you pulling the icons straight from the Metrostation app? It almost sounds like somehow the icons are in JPEG format instead of png.

Tap'd from my Maxx