Removing white artifacts from composition I'm trying to compose two layers into a single one. The first layer contains the image itself and the second one the lines from freestyle. Here are my nodes: 

I want the first layer to have some lower opacity while the second one to be completely opaque. However whenever I join both layers some white artifact appear around the lines. How I convert then to the color of the line itself? If I connect the freestyle layer to viewer it seems correct.
Set this transparent color to black (also transparent, but base on black):



Also try z-combine instead of Alpha Over: