This is another simple tutorial, for adding a nebula effect to a starfield. First, you need to generate your starfield – you’ll find the method explained here. Again, I’ve only done this in Photoshop so if you want to use a different program like GIMP, some of the filters might not work or have different names.
1. Make a new layer on top of your starfield layers, fill it with black, and set your background colour to whatever colour you want your nebula to be. Then go to Filter > Render > Difference Clouds.
2. Still with the same layer and everything, click on “Difference Clouds” again.
3. Add a little Gaussian blur. You can skip this step, but I think it looks better.
4. Set the blend mode to “Screen” and voila!
5. If you want more nebula, create a new layer on top of the others. Fill it with black, pick a different background colour, and generate difference clouds again.
6. Remember to click it twice.
7. Optional Gaussian blur – play around with different amounts to get different effects.
8. Set the layer blend mode to “Screen”.
9. Adjust the opacity until it looks good. I’d suggest keeping one colour more in the background (in this case, the purple is set to 60% and the turquoise to 100%).
10. Turquoise nebula set to 90% opacity, purple set to 60%.
This works on any size of canvas, but if you’re going to use a big one, I’d suggest generating the nebula in a small canvas and then resizing it to fill the bigger one, otherwise it’ll look weird, like this:
The image will get blurrier when you resize it, but since the nebula is blurry anyway, it doesn’t really matter.
That’s it! If you want to save this tutorial, here’s the whole thing in one handy graphic – just click on it to get the full-size version, and save it.
You can use this as is, or you can use is as a background for a painting. If you want to add more stars or nebula effects manually, I also have some brushes available to help with that. If you do make something with this, as always, I’d love to see it!