Render the alpha of a contour?

[JasonFerry]

Hey guys, quick question.  How could I render the alpha of a contour line from a toon material?  I have a picture to show what I'm working on, I'm just trying to render without that white fill. 

Thanks!

[Esben Oxholm]

If you take the transparency slider in the toon material to 1 and render as png including alpha, then you should get the lines only.