1. First step is pretty simple, fill the canvas with black, run add noise with 0 saturation. Then brightness contrast -25/75
2. Open up a new canvas that is 2x your starscape canvas, fill the canvas with black, then add noise at the same settings as earlier.. Run brightness contrast at -100/50, then run median with 100 percentile and a 1-3 radius. Next run a 1-2 px gaussian blur if you want. Now copy+paste and scale it down to your starscape's size, set layer blending mode to screen. Flatten all layers together.
3. Now add a black layer this, and just erase the stars layer randomly, with a 50-100 opacity eraser. Make sure AA is off when you use the eraser.
4. Here's the part where you really go crazy Merge down with your black layer, then duplicate. Grab the clone stamp tool, then randomly clone stamp from the star layer onto a new layer. make sure AA is off when you use the clone stamp. On the new layer you can set it to normal to just cover the old stars, or set it to screen and have it add to them. Also, you can mess with the opacity of these new layers. Merge down then repeat the process until you get something you like. Try to pick some areas where there won't be many stars, and some where there will be a bunch all clumped together.
Optional: You can try clouds with a small scale, then run dents with a large scale. Select this layer and put it to color dodge, then erase any big clumps of white that stand out.
5. Once your done with that, make sure it's all flattened then duplicate the layer. Run gaussian blur at 6-8 px then go to color tint/color filter/curves or whatever, and then color this new layer, then set blend mode to additive. If you want, you can repeat the process with a smaller guassian blur radius.
6. Now you can add some larger stars if you would like, but I'm not going to.
7. Last and optional step, is to add some atmospheric dust. Personally I just render clouds at default settings, then dents with a large scale and a stretch of 1-2 towards your light source/planet. Then run alpha mask without a mask loaded to get rid of the black, then set to a really low opacity.
And now your done! Comments/criticism/questions welcome
Edited by Sharp, 30 March 2011 - 12:38 AM.