Karmay - Create startrails with Photoshop

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    I created this Photoshop tool as an alternative to other software that lets you stack pictures to make star trails. I don't mean to compete with those programs, I just needed something that suit my needs. I guess I'm not the only one who faced some issues I found with StarStaX, so I decided to share this script so everybody can use it.

    A simple alternative to StarStaX

    Markus Enzweiler's application is, I think, the first one anybody who wants to create star trails would use, but it has some things I'm not very happy with, so I decided to develop this script that takes advantage of Photoshop's engine to solve some of the issues and limitations I encountered with StarStaX. They are just three, but let's see a comparison anyway:

    Supports raw/DNG files
    Supports lens correction
    Reads Lightroom/CameraRaw XMP metadata
    Is it free?
    Cumulative image saving
    Noise reduction using dark images
    Supports image compression
    LanguageEnglish and SpanishEnglish, Spanish, German, French and Italian
    Gap filling
    Star trail looks43
    Blending modes19
    PlatformWindows and macOSWindows, macOS and Linux

    On the table above I listed the most importante functions without too much thinking, but I insist, I don't mean to compete with anybody, so I won't make a huge list of every single thing. But the most important thing to me and the reason I needed an alternative is because I hate to convert every image sequence from raw to TIFF to be able to create star trails (they take too much space). And second, if I do a lens correction before making the star trail picture, strange and horrible lines appear in the final image, as you can see in this 100% crop (pay attention to the mountain):

    So, for those two reasons in particular I prefer to use Photoshop to create star trails images, because by using that application I can do everything I need from StarStaX and I can do it without converting from raw to another file format, plus maintaining the develop adjustments I apply in Lightroom or CameraRaw.

    Star trails look gallery

    As I said above, the script creates 4 different types of look, you can see them here:

    • Regular star trail: the most common star trail we all know about, equal from end to end.
    • Comet star trail, left to right: this look creates a comet-like trail. On one end it has 0 opacity and it goes up to 100 to the other end.
    • Comet star trail, right to left: this is the same as above but the opacity is inverted, from 100 to 0.
    • Iridium flare star trail: this look has 100 opacity in the center and goes down to 0 on both ends, that's why I compare it to an iridium flare. It's for me the most stylized one.

    Please note that I used 100 pictures for every example.

    How do I use the script?

    1 - Download the script from this page (above are two options to download) and unzip the file.

    2 - Open Photoshop and close all documents.

    3 - Go to File > Scripts > Browse...

    Paso 2

    4 - Search for the file Karmay_v1.x.jsxbin you unziped on step 1 on open it.

    5 - A window to select a folder will open. Choose the folder with the pictures you want to work and make star trails.

    Tip: if the files are raw imagenes and you first develop them using Lightroom or CameraRaw, the script will read those adjustments. Just make sure you saved the metadata to the XMP files (in Lightroom this is done by right clicking on an image then Metadata > Save Metadata to File)

    6 - A little window with options and buttons will open:

    This is the script, it's super simple. You now have to select a star trail look (I tried to get as closed as I could with just text lines instead of images) and then click on Create star trails. That's it! Then you have to wait for Photoshop to do its job, If you loaded a lot a pictures the program will take longer and vice versa.

    Free of charge software

    The script is completely free, but I added the option to make a donation on the top of the page if you want to do that. Donations help me keep creating this kind of tool completely free of charge.

    Version history


    • First version, for private use only


    • First public version
    • The interface got a lot better
    • Fixed a bug to make the Help button work in macOS
    • I named it Karmay (it used to have a horrible generic name)


    • CR3 files are now supported

    Keep yourself updated

    You can subscribe to any of my lists to be the first to know about the script updates, new courses, new workshop dates, get new blog posts, store items and much more. I promise to respect your privacy.



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