capturing jit.gl.sketch to texture - how to get smooth lines?

I am using jit.gl.sketch to draw opengl. As i want to be apply further jitter effects (shaders,etc) onto the sketch output, i capture the opengl to a texture. Yet when i do that, the output gets more jagged, the lines are not smooth. I tried all different settings (fsaa, antialias, interp, ...) on the various objects involved (jit.gl.render, jit.gl.sketch, jit.gl.texture, ...) but i haven't found any solution yet.

I also tried the jit.gl.render-tomatrix example, but the lines are not smooth in that example either.

Any ideas?