Star Enhancement in Night Skies

JimFox

Moderator
Staff member
Have you ever been out at night shooting the night sky, and the stars are twinkling all over and making the night feel alive? Or you could be in an area where there is more light pollution and the stars are trying to put on a show, but are having difficulties? This is a way to get your stars to show up a bit more in your night sky shots.

One of the Benefits of this process is it does also help to sharpen your stars for you without having to do any sharpening.

First, I want to suggest to make sure in ACR you use the DeHaze slider to help darken the background skies which also helps to get the stars to show up more.

So now start with your image in Photoshop, it doesn't matter which version of Photoshop.

1. Just duplicate the Layers twice in Photoshop.

2. On the top layer draw a selection that goes just below the top of the Butte, but on both sides angle up some to keep the selection in the darker part of the sky. (You are doing that to keep the brighten of the stars to just the darker part of the sky so the lighter part of the sky along the horizon doesn't get brightened) Create a Layer mask from that Selection. (Press Alt and click on the Create Layer Mask Icon)
Star Layers2 Small.jpg



3. Select the Middle Layer. Zoom in closer so you can see the stars, maybe 100%.

4. In the Selection Menu use Color Range and click inside a star. Then adjust the Fuzziness to somewhere around 100, but do it to taste.
Star Layers Color Range1 Red small.jpg



5. In the Selection Menu go to Modify then to Expand, and Expand by 1 Pixel.

6. Press the Alt Key and click on the Make Layer Mask Icon in the Layer tool box to create the Layer Mask for the stars.
Stars Layer Mask Selection.jpg


7. Go back to Normal view on the image so you can see the whole image.

8. If your night sky is not dark enough for you, this is a great time with that middle layer to then just go into the Levels or Curve adjustments and bring down the Midtones slightly. Watch your feathered edge at the bottom to make sure the darkening looks natural. Because the stars are in the Layer mask, darkening the middle layer won't darken the stars.
Star Layers Darken Sky small.jpg



9. Now is when the magic happens! Click on the bottom layer. Go to the Edit menu, select Layers. Now raise up the brightness of that bottom layer until you see the stars a little better.
Star Layers Brighten Stars small.jpg



Make sure to keep it natural looking, you can over do it and the stars will be too bright and look fake. The stars can get lost in a photo, where in person it's easy for us to see them. So this is an easy way to help the viewer who wasn't there to also experience the stars.

This whole process once you have done it a time or two shouldn't take more then 2 or 3 minutes.
 
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Kyle Jones

Moderator
Nice, I'll have to play with this. My favorite trick is using a luminance mask and selecting everything but the stars. With that as my selection, I create a levels layer and pull the whites slider to the left and the middle slider to the right until things look good. I can see this as a nice addition to the toolkit.
 

JimFox

Moderator
Staff member
Thanks Kyle, that would be a great way to do it too. I am sure there is more then one way to do it.
 

Kyle Jones

Moderator
I gave this a try this weekend and like the flexibility that it gives me - especially if I just want to use a mask to brighten specific stars. In case it helps anyone, you can use Jim's technique without having to copy the image layers. If you are using a high resolution camera and already have multiple layers, you can quickly approach the maximum TIFF file size.

I replicated the technique with the top 3 layers in this image. I created a star selection using the "select color" and expand technique that Jim described. I used that as the layer mask with a brightness layer to brighten the stars. Then I inverted that selection and applied it to a levels layer to darken the sky. Finally I created a group ("Group 4" below) of those two layers and created a layer mask to limit the effect to the portions of the sky where I wanted it. This essentially does the same thing that Jim described with what should be a smaller file size.

brightstars.jpg
 
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