I've got a nice starfield material that starts off with a small b/w texture (like 200x200) and produces a fairly random looking starfield with varying levels of brightness, colors. and density. It can do very large render areas without looking repetitive, i.e. it's NOT tiled. I'm including a small sample of the output here. Given the complexity of the material node arrangement, it renders remarkably quickly.

Unfortunately, the process effectively guarantees that all the stars are only a single pixel. (There are few exceptions, but it's really just two stars on adjacent pixels.) That's fine for the really dim ones, but I'd like the bright ones to bleed over into adjacent pixels, kind of like a glow or lens-flare effect. So, I'm wondering if anyone can think of a way to add that kind of blur as a material-node post-process to occur during the render.

I know that I could just turn the sample into a texture map with some Photoshop mods on it, but it would have to be a big texture, and I'm already running low on RAM for this scene.

Alternatively, I would want to blend in multiple instances of a single larger star, but I can't think of a way to get that without it forming an obvious pattern, e.g. tiling.

Any ideas?