StarStaX Icon

StarStaX - Version 0.71

01) Introduction
Photo Gallery
Change Log
Known Bugs
Blending Modes
Usage & Tutorials
System Requirements
Download and Installation
Frequently Asked Questions
11) Credits

Download StarStaX


StarStaX is a fast multi-platform image stacking and blending software, which allows to merge a series of photos into a single image using different blending modes. It is developed primarily for
Star Trail Photography where the relative motion of the stars in consecutive images creates structures looking like star trails. Besides star trails, it can be of great use in more general image blending tasks, such as noise reduction or synthetic exposure enlargement.

StarStaX has advanced features such as interactive gap-filling and can create an image sequence of the blending process which can easily be converted into great looking time-lapse videos.

StarStaX is currently under development. The current version 0.70 was released on December 16, 2014. StarStaX is available as a free download for Mac OS X, Windows and Linux.

Please send feedback, bugs, results and suggestions via e-mail to:

Photo Gallery

Check out the
StarStaX Flickr group for some great photos created using StarStaX!

Did you get some nice photos using StarStaX ? Let me know!

Features - Version 0.71


  • Blending/stacking modes: Lighten, Darken, Average, Addition, Subtraction, Multiplication

  • Interactive gap filling mode to automatically close small gaps in star trails (see the gap filling tutorial)

  • Comet mode blending to create comet-like star trails

  • Interactive help browser with documentation, tutorials and web resources

  • Supports a multitude of image formats (JPG, TIFF up to 16-bit/channel, PNG, etc.), Raw images cannot (yet) be developed using StarStaX - there are many better tools for that. For Raw images, use your favorite Raw converter, make your adjustments and export the images as TIFF.

  • Cumulative mode: A stacked image can be saved after each frame is processed (to create a cumulative stacking video)

  • Averaging and subtraction of dark frames to remove hot pixels and noise

  • Smooth zoom, 100% view, different view interpolation modes (anti-aliasing)

  • GPU support for fast navigation within images

  • Multi-touch / mouse wheel support for scrolling

  • Multi-CPU / multi-core and SSE optimized for processing speed

  • Multi-language (currently: English, German, French, Italian and Spanish)

  • StarStaX is fully 64-bit enabled on all platforms

Change Log

Version 0.71

Version 0.70
  • StarStaX is now a 64-bit application on all platforms
  • Bugfix in multiply images
  • Fixed a memory problem with large images under Windows
  • Switched to Qt5 as underlying toolkit
  • Support for Mac OS X Yosemite (10.10)
  • Enhanced full-screen experience on Mac OS X
  • French and Italian translations

Version 0.60
  • Comet mode blending to create comet-like star trails
  • StarStaX help browser with documentation, tutorials and web resources
  • Improved Drag and Drop support
  • Improved retina display support (Mac OS X)
  • Minor changes in gap filling algorithm
  • Linux builds for Ubuntu 13.04
  • Experimental build for Mac OS X Mavericks (10.9)

Version 0.52

  • Bugfix: Fixed dark frame subtraction which gave wrong results in version 0.51

Version 0.51

Version 0.41 (bugfix release)

  • Bugfix: Fixed flickering issue on Windows 7 when saving cumulative images
  • Windows version is now considered stable

Version 0.40
  • Experimental Windows version released
  • Cumulative saving mode. Save the current stacked image after each frame (to create nice videos)
  • Automatic check for program updates
  • Scrolling mode can be inverted to simulate iOS scrolling
  • GUI enhancements (tooltips, tab order, focusing, etc.)
  • Further SSE speed optimizations
  • Bugfix: Application menu now translates correctly on the Mac
  • Bugfix: Lossless TIFF compression now works as expected
  • Bugfix: Enhancements to smooth zooming

Version 0.31 (bugfix release)
  • Bugfix: Keyboard zoom speed no longer depends on system keyboard repeat rate setting
  • Bugfix: Fixed progress bar settings when dark frame subtraction is used

Version 0.30
  • Dark frame subtraction
  • SSE speed opimization for blending

Version 0.20
  • Average, Addition, Subtraction, Multiplication blending modes
  • Smooth zooming and anti-aliasing
  • Multi-Core optimization

Version 0.10
  • Initial release

Known Bugs - Version 0.71

Mac OS X version

  • none
Windows version
  • none

Linux version
  • Very large images may not be displayed correctly, although the final saved image looks fine. This will be fixed in the next version. If you are experiencing this bug, let me know and I’ll help you out.

Blending Modes

Lighten: Compares the images and chooses the brightest pixel at each location. Use this to create star trails. If your camera pauses between consecutive exposures, there might be small gaps in the resulting star trails. In that case, the "Gap Filling" mode should be used, see below.

Gap Filling: Optimized 'Lighten' blending mode which tries to eliminate small gaps in star trails. The user can choose a threshold to limit processing to certain regions of the image (e.g. only the star trails) and control the amount of gap filling to be applied. See the corresponding
gap filling tutorial.

Comet Mode: In 'Lighten' and 'Gap Filling' modes, StarStaX offers a 'comet mode' which adds a fading effect to the end of the star trails, simulating the look of comet trails. The length of the trails can be varied, of course.

Darken: Compares the images and chooses the darker pixel at each location. Use this to remove star trails.

Average: Averages the individual images. This can be used to reduce random noise from a set of photos of the same scene, thereby creating smoother images, particularly in image regions with low brightness and color variation.

Addition / Subtraction / Multiplication: Adds, subtracts or multiplies the images. Adding is particularly useful to synthetically generate longer exposed images from a set of individual images of the same scene. Here, the exposure of the stacked image is equal to the sum of the exposures of the individual input images.

Dark frame subtraction: When dark frames, i.e. photos taken with closed shutter or lens cap on, are available, they are averaged and automatically subtracted from each input image. This can reduce sensor noise and remove sensor pixel errors (hot-pixels) in the final image.

Usage & Tutorials

StarStaX has been designed to be easy-to-use without a steep learning curve. To get started quickly, take a look at this
tutorial and the help browser included in StarStaX. There are tooltips available for most of the options and features of StarStaX. Just hover the mouse pointer over user interface elements of StarStaX to get a quick explanation of the underlying features and options.

Here is a quick overview of general usage:

  • Load input images (menu bar or icon), optionally: load dark frames

  • Select blending mode in preferences

  • Start blending

  • Save output image

Zooming / Scrolling
  • Plus ("+") and minus ("-") keys for smooth zooming

  • Click and hold left mouse button to drag the image

  • Horizontal and vertical scrolling with mouse wheel or two-finger multi-touch gesture

  • Double-click to center view on an image area (this area becomes the new "focus" for smooth zooming)

  • "F" key to fit zoom to window size

  • "Z" key for the all important 100% view

Cumulative Videos
  • Select cumulative saving in "Blending" preferences tab

  • An image will be saved to the specified location after each image is processed

  • Use your favorite tool, to convert those images to a video, e.g.:
    Mac: Time Lapse Assembler (freeware), ffmpeg or mencoder
    Linux: ffmpeg or mencoder,
    Windows: VirtualDub

System Requirements

Mac OS X version
StarStaX requires Mac OS X 10.7 Lion or higher and a 64-bit capable Intel processor (Intel Core 2 Duo or better). To find out if your Intel Mac has a 64-bit CPU, please refer to:

Windows version
StarStaX requires Windows 7 or higher.

Linux version
StarStaX has been tested on Ubuntu 12.04, 12.10 and 13.04. It may or may not work on other distributions.

Requirements for the Ubuntu 12.04, 12.10 and 13.04 versions:
glibc >= 2.15, libjpeg62, freeglut3

Download and Installation

StarStaX is available as a free download for Mac OS X, Windows and Linux. There are no ads or other money-making schemes whatsoever.
If you like StarStaX, buy me a coffee or a beer :) Thanks!

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Please let me know on which OS you are running StarStaX. Thanks!

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Installation instructions are given below:

Mac OS X 10.7 (OS X Lion) - 10.13 (OS X High Sierra)

StarStaX version 0.71 is available as a .dmg file from here: StarStaX-0.71_Mac.dmg
Mirror: StarStaX-0.71_Mac.dmg or StarStaX-0.71_Mac.dmg

Webspace provided by

Download and mount the disk image and drag StarStaX to your Applications folder.

In case of problems opening StarStaX, please see this FAQ entry!

Windows 64-bit

StarStaX version 0.71 is available as a .zip file from here:
Mirror: or

Webspace provided by

Extract the .zip archive and double-click on "StarStaX.exe" in the folder StarStaX-0.70. There is no installer. You can manually copy the StarStaX folder to any folder you like and create a link to StarStaX.exe, e.g. on the desktop or in the program menu. To uninstall just remove the StarStaX folder from your harddisk.

You may need to install the Microsoft Visual C++ Redistributable Package to install the necessary run-time components. To do so run vcredist_x64.exe and follow the installer.

See the “readme_install.txt” file in the .zip archive.

Other versions

Windows 32-bit

StarStaX version 0.70 (32-bit OS) is available as a .zip file from here:

Linux version (stable)

StarStaX is available as a .tgz file from here:

Ubuntu 12.04 and 12.10 (x86, 32bit)

Ubuntu 12.04 and 12.10 (amd64, 64bit)

Ubuntu 13.04 (x86, 32bit)

Ubuntu 13.04 (amd64, 64bit)

Download and extract the .tgz file. Execute the start script '' .
See the system requirements above.

Frequently Asked Questions

Q: Can I host a copy of StarStaX on my server ?
A: No. Please refrain from doing so. Use a link to instead.

Q: Will there be a version for Mac OS X 10.4, 10.5 or 10.6 ?
A: On the Mac, OS X 10.7 Lion is the absolute minimum requirement.

Q: Does StarStaX run on my PowerPC (G4 / G5) or Intel Core Solo / Duo Mac ?
A: On the Mac, at least an Intel Core 2 Duo processor (64-bit) is required. There is no PowerPC support.

Q: Can you implement feature XXX ?
A: StarStaX is developed in (valuable and scarce) spare time, so feature requests cannot be handled immediately. I am constantly developing my own ideas on how StarStaX could be further developed. If you have a good idea, let me know.

Q: Why can't StarStaX read my Canon/Nikon/Sony etc. raw camera files ?
A: Raw development is a highly non-trivial problem. While a simple raw plug-in could be included rather easily into StarStaX, it's quality would certainly not be on par with available commercial and open-source products (Aperture, Lightroom, RawTherapee, etc.). That's why there won't be any raw support in StarStaX in the near future.

Q: On my Mac, I get the message “StarStaX cannot be opened because it is from an unidentified developer”. What can I do ?
A: This message comes from the “Gatekeeper” of Mac OS X. To open StarStaX, right-click on, select open and confirm the following dialog. From then, can be started as usual. Another alternative - although not recommended - is to disable Gatekeeper completely. See this
Apple support document for further details.

Q: How can I choose the image format to save my stacked image in ?
A: StarStaX guesses the format from the file name. Simply add your favorite image extension to the filename in the save dialog, e.g. myGreatStackedImage.jpg.

Q: Cmd+A does not work on Mac OS X to select all my images !?
A: This is a known bug. As a workaround, you can select the first and last image while holding down the Shift key.

Q: Is StarStaX available in my favorite language ?
A: StarStaX is localized to English, German and Spanish. If you want to help in translating it to your native language, let me know!

Q: I think I have found a bug in StarStaX !
A: Let me know and tell me how to reproduce it.

Q: Where can I get some help / tips on using StarStaX ?
A: You might wanna take a look at the StarStaX Flickr Group.

Q: StarStaX ? What does that mean ?
A: StarStaX is a Star Trails Image Stacker for Mac OS X.

Q: Is StarStaX open-source / Do I have do pay for it ?
A: StarStaX remains closed-source for now and is available as freeware. It uses (and dynamically links) to the Qt framework which is used under the LGPL Version 2.1 license.

Q: I want to credit StarStaX !
A: Please use a link to


Thanks to