Adding Stars to Images
This is the finished image of this tutorial, a sky with stars!
I'm going to show step by step how to do it. First open your picture, I used this one:
Now create a new layer above your picture layers, rename it to "stars"(double click on the layer name) and fill it with black (pressing D, then alt+F)
Now, with the stars layer selected, go to Filter > Texture > Grain, use this settings:
Now set the "stars" layer to Screen mode(Layers Tab).
Now, with a soft brush, erase the stars that are above the river and the buildings (leaving only the ones at the sky), use the erase tool (E) to do this.
Now, again with a non-soft brush of about 20 px, erase some stars in the middle of it, because there are too many stars on this sky. Don't forget also to erase the stars that are too close to the buildings, because on a true sky you would not be able to see those stars because of the buildings' light.
Now set the stars layer opacity to about 60% (layers tab).
The issue we have now is that some stars on a real sky are more bright then others, so we have to solve this problem.
On the stars layer, click on "create layer mask".
Now ctrl+click the stars layer and use the gradient tool from left to right on the picture. But before, make a somewhat crazy gradient like this one, variation from light and dark colors.
When it's a light color, the stars disappear, when it's darker, they appear. So some of the stars will be more bright than others!
You are done!
Hover over to see "before" image.
I hope that you enjoyed this tutorial.