In this tutorial, we will use Adobe Photoshop to create star trails from a single photo. We are going to use a seldom-used “Duplicate Transform” trick to quickly create streaking stars and trails of light that drift across the sky. We will tackle some of the pitfalls you may encounter along the way and learn to fix drifting and dragging pixels, streaky lights, objects in the sky, cloning and healing with Photoshop, Content-Aware Fill in Photoshop, as well as some light blending to help pull the entire image together in the end. If you want to learn to create starlight trails in Photoshop, this is the tutorial for you!
Duplicate the layer so we can begin to work on the sky and prepare it for the mass duplication we’re going to hit it within a few moments.
I’m looking to remove or reduce big light spots, airplanes, big and bright planets, comets, etc…
On this duplicated layer use your favorite method of healing. I am using the Patch tool and then the Healing Brush tool to touch up the sky and make it good enough to work with.
TIP: Reduce the diffusion on the Patch and Healing brush tools for best results with something like a starry sky.
Use the Quick Selection tool to make a rough selection of the foreground. Use the hotkey Cmd/Ctrl + J to duplicate this up to a new layer.
Select the layer below (containing the entire foreground and the starry sky) and duplicate it. NOTE: When you don’t have a selection created and you use the hotkey Cmd/Ctrl + J the entire layer will be copied, not just the area selected.
The layer you should have selected is the layer just below the foreground we just duplicated up to its own layer. This is the top-most layer that contains our entire photo.
Set this layer to the blend mode Lighten.
Use the hotkey Cmd/Ctrl + T to free transform this layer. Find the Rotate input field in the top control bar and set this field to “0.1” and commit the change.
Now use the hidden hotkey Cmd + Shift + Opt + T. This will duplicate the current layer AND apply that same transform we just did to the duplicated layer. Hit this hotkey about 40x.
We’re going to do this a couple of times because I want to show you some of the common problems you will likely encounter and the quick fixes that will make your life much easier.
Duplicate layers before any destructive bits.
Make a general selection of the foreground and copy it to a new layer.
Make a big, soft selection of the sky and pop that up onto a new layer.
Duplicate this initial sky layer.
OPTIONAL: Use the Levels adjustment on this star layer before beginning to boost the darkest parts of the sky to eliminate the haze that might be introduced by galaxies, and clouds, or simply to reduce the number of star trails and lessen the overall effect.
Set it to Lighten.
Duplicate this layer and shut it off. We might need it later and it’s very important to have access to it.
Use Free Transform to tip the stars +0.1 NOTE: Anchor point is super important!
Group these layers into a folder.
Go back to the original sky layer and Free Transform to tip -0.1
Group these layers together.
Merge these layers together. NOTE: You can convert to a Smart Object if you don’t mind a huge file size. This will allow you to still have access to all of the individual layers that we transformed.
Add a very small gaussian blur to this merged layer (or Smart Object) to lessen the effect a little.
You can also go in and use the Blend If sliders to blend the start trails in a little more. Generally, if the effect is too strong, or too weak and missing too many stars, you need to apply a different amount of that Levels adjustment that we did to the sky before beginning to duplicate this starry sky.
Because this layer or Smart Object will be set to the Lighten blend mode, you can apply a Levels adjustment directly to this layer (or clip a Levels Adjustment layer to this layer)and tweak the black levels to adjust the blend of the star trails.