Actually, no curve nodes are used and the setup’s a bit more complex. For example, to get the bright areas of the image to cause glow around the emitting and very bright objects and textures I used a brightness/contrast node with contrast way up and brightness way down and blurred it.
It’s not like I blurred the whole image then mixed it in with the unchanged version, as that would cause glow on everything.
I just tried it and it didn’t seem I needed any explaining to get it to work, only changes I made was changing the blend mode when I did the final mix (I used lighten instead of screen or add to avoid too much washout). And I converted the color to greyscale (so when I connected a viewer node to the curve output I can better see where the blur will be the most).
The blur node uses the greyscale value to affect the size of the blur.
EDIT: I’ve been testing your setup on this image, at first when I just did it the way I did last time, it provided sky blur, but the red on the round object wasn’t glowing, I made a few changes including resetting the blend mode to add and not putting anything to control blur size and I got some mighty fine glow from the sky and the emitting texture, but ray transparent surfaces with sky only didn’t convey the glowing effect correctly and there was nothing that controlled the size of the blur.
I’m rendering the image again with the sky in the first renderlayer, if I don’t see good glow bleeding through transparent objects, then I would’ve found pretty much the one weakness in your suggested setup. Though I have to say, it probably can be fixed by the technique on how I achieved sky glow on my thread at finished projects with the difference that the sky goes to its own layer.
EDIT 2: tried it again, and I did seem to find 2 weaknesses in your suggested setup using a curve node
1). Glow not bleeding properly throughout the whole of a ray transparent object when there’s sky behind it, it acts as if it was solid, it. Removing the sky from the layer seems like it’ll be able to glow through properly though it’ll require a more complex setup and another renderlayer (one that has the sky), you could also probably fix this by using an object for the sky, though it may not be fully convienent for animators.
2). I can’t seem to use the increased contrast generated by the curve to also affect the size option in the blurring.
I have successfully tested this on one image, but it was already rendered and saved and thus it was purely a PostPro effect, animators and artists alike may want to see the composite whenever they render out their scene again and again. Otherwise you’re just using Blender’s compositor like you use photoshop on a saved image.
Oh, that’s not a ‘setup’, I was just making a wild guess, because in your original post you seemed to be holding out for people to ask you for yours. My setups are usually a little more extended than just the three things.
