Star reduction for astrography

I know this may sound a bit unusual to remove the stars in your Milky Way photo, but in fact, there are plenty of pro photographers doing that.

There are two reasons why we want to reduce the stars.

First, too many stars can be quite distractive. Usually, we tend to increase the contrast of the photo to make the Milky Way “pop”, but this also applies the same to the stars. You would want your viewers to focus more on the Milky Way instead of the “bright spots” that scatter around the sky.

Second, reducing the size of the stars can also help to make the Milky Way stand out from the frame. This is simply because the stars around the Milky Way are the densest. Reducing the stars would also reveal more details of the Milky Way.

Now you have a better understanding of why applying star reduction, here’re the steps on how to do it on Photoshop.

Usually, I apply the Star Reduction only at the very last stage of my editing workflow. If you prefer to do the same, you need to first merge all the layers into a new layer by pressing Ctrl + Alt + Shift + E (Window) shortcut keys.

Now, select the newly created layer, go to Select > Color Range. The Color Range window will prompt on your screen, and your mouse cursor will automatically turn into Eyedropper tool.

Make sure the Select option is Sampled Colors, use the Eyedropper tool to click on the white stars. Then use the Fuzziness slider to control the range of the Selection. For our case here, we try to select most of the bright stars.

Once done, click OK to create the Selection.

This is how the Selection looked.

Now go to Selection > Modify > Feather and set the Radius at 1 pixel. Then click OK to apply the change.

The last step is to go to Filter > Other > Minimum and set the Radius value somewhere between 0.4 to 0.8 pixel. Also, make sure the Preserve mode is Roundness.

Click OK to apply the change, and you should be able to notice the brightness of the stars is reduced now.

Here’s the before and after comparison. Left is original, right is after Star Reduction.

This is an optional step. If you think the effect is too strong, you can reduce the Opacity of the layer.


Here’s the before and after comparison in the full-size image.

That’s all for this article, if you are interested to learn more from me, you could check out my upcoming ONLINE ASTROPHOTOGRAPHY WORKSHOP in below. 🙂



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