Got a Chromatic Aberration removal plug-in for Gimp and just used negative values to create it. Took me ages to get the desired look.
The first time I got the idea was using a plugin called PTLens, which is a plugin designed for removal of lens artifacts.
What’s cool about PTLens is that they update it with data from actual lenses. Of course the idea is that the processing is designed to counteract the lens artifacts, but that also means that if you apply these corrections to an image that is already perfect (a render), then the effect is opposite, it actually adds lens artifacts to an otherwise perfect image, making it look as if it was actually shot through whatever lens you choose as the lens you wanted to correct. However, I don’t use it now unless it’s needed on an actual photo. For renders, I prefer to create the effect manually which in turn, gives total control over the look.
Quick Manual Chromatic Aberration Tutorial:
1 - Split your image into RGB or CYMK channels
2 - Apply a moderate horizontal motion blur on one of the channels
3 - Reconstruct the channels and you’ll have a basic Chromatic Aberration effect
For anyone new to the effect, that’s a great way to get started without needing a plugin. But once you try doing it manually, there are endless amounts of things that can be done to get better control over it. It can be as easy or as advanced as you want it to be. A more advanced technique is to use a Barrel or Fisheye distortion in gradually increasing amounts in each channel. This not only gives a very prismatic, crystalline sort of quality, but gives you some lens distortion into the bargain. I could go on and on about more and more advanced techniques, but anyone who tries this will automatically advance their grasp of things and figure them out anyway.
Basically though, it’s an important effect if you’re going for the look of a photograph. Chromatic Aberration of the variety we are talking about here, is something that is consciously noticeable because we can actually see the fringing. But there’s another type of Aberration that goes unnoticed, something people don’t talk about because they don’t know it’s there. I’m not going into that because it would require a fairly long tutorial, but for me at least, it highlights the importance of using these effects on renders that are intended as photos.