dont use Filter-Extract when u are doing the Rendering. I suggest the Polygonial Lasso Tool. And do it VERY upclose like by pixel. It goes slowly. But u get the effect u want.
SomethingCreepy is correct. I zoomed in real close and did this attachement... It is a pain in the butt but if you want a clean and sharp render it is well worth that time it takes.... I did not clean up very well but you get the idea...
um, i didnt use filter extract, i didnt even know about that, i always zoom in close but i use a standard eraser tool. ill try the lasso tool sometime
Lil bits of a render that don't get done well don't really matter, especially hair in my mind since your just going to blur, feather or w/e you do to make it look good... and if you really need a touch up just get an eraser tool and run over the hard lines. I think its good, cred if I use.