A Guide to the Best Astrophotography Stacking Software

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Explore the world of astrophotography stacking software with this guide, helping you make informed choices based on your skills, budget, and preferences.

Have you ever taken photos of nebulae or galaxies or even just nightscapes and been a little disappointed with how the raw images looked compared to other astro photographs you had seen?

To achieve that result, you will need to take several photos of the same star field and then stack those photos.

Among the many techniques employed by astrophotographers, stacking is a crucial process that involves combining multiple exposures to create a single, enhanced image.

This technique not only reduces noise but also brings out intricate details in celestial objects. To achieve the best results, photographers rely on astrophotography stacking software.

Let’s explore and evaluate some of the best stacking software available, catering to a variety of skill levels and preferences.

Before we delve into the specifics of various stacking software, it’s essential to understand why stacking is a fundamental practice in astrophotography.

Noise reduction – Stacking helps reduce the impact of random noise in images by averaging out pixel values. This results in a cleaner and smoother final image. To get a little more technical, when we stack and average exposures, we reduce the noise by the square root of the total number of exposures.

Enhanced details – By aligning and combining multiple frames, stacking reveals finer details and fainter celestial objects that may be imperceptible in a single exposure.

Increased dynamic range – Stacking allows for the simultaneous capture of both bright and dim elements in the same image, expanding the overall dynamic range.

Both the enhanced details and the increased dynamic range are a consequence of having a better signal-to-noise ratio, as this allows us to process the image resulting from the stack more aggressively.

Now, let’s explore some of the best astrophotography stacking software options available on the market. Of course, there are many more options out there than the ones we will look at here, but these are options that I know well/have had experience with.

You can stack and average astrophotos in Adobe Photoshop, but using astrophotography-dedicated software will definitely offer you more options.

1. Starry Landscape Stacker

Starry Landscape Stacker is the most basic of the stacking software I will recommend. It’s very useful for astrophotographers who mainly shoot nightscapes.

The software will align only the sky part of the frames while keeping the foreground fixed but will stack and average both parts of the image. This way, you will get both the foreground and the sky sharp and a better signal-to-noise ratio across the whole image.

Starry Landscape costs 40 USD and is only available for MacOS. For Windows, you can use Sequator, which is free and has some additional options too.

2. DeepSkyStacker

DeepSkyStacker (DSS) is widely used and reliable stacking software, particularly favored by beginners. It is a Windows-based application that offers a straightforward interface and robust features, and it’s free.

DSS features an automatic alignment function that compensates for minor tracking errors or shifts between frames, ensuring precise alignment. The software also allows for the subtraction of dark frames to further reduce thermal noise in the stacked image.

It supports the stacking of both light frames (the target images) and flat frames (used to correct for optical imperfections), providing flexibility in the stacking process.

3. RegiStax

Registax is the king when it comes to planetary imaging. Compatible with Windows, RegiStax is known for its advanced features and unique wavelet processing. And just like DSS, RegiStax is free.

It is quite easy to learn its basics, but you will need a bit of time to fully master this piece of software.

RegiStax’s wavelet processing feature allows for detailed adjustments to different spatial frequencies in the image, enhancing fine details without compromising overall image quality.

The software automates the alignment and stacking process, saving time and effort for astrophotographers. It supports a wide range of file formats, making it compatible with different cameras and image types.

4. PixInsight

PixInsight is a comprehensive image-processing software designed specifically for astrophotography. While it comes at a cost (EUR 300 + VAT, at the time of writing this article), its advanced features and capabilities make it a favorite among experienced astrophotographers.

To me, PixInsight is the best astrophotography software ever written. It works on MacOS, Windows, and Linux.

PixInsight takes advantage of multithreaded processing, allowing for faster and more efficient image stacking and processing. It provides advanced tools for image calibration, including the removal of biases, flats, and dark frames.

PixInsight supports batch processing, enabling the automation of repetitive tasks and streamlining the workflow for processing multiple images.

You just need to dump your lights, darks, flats, and bias (if you need bias) frames in a bin, and the software will take care of calibrating, aligning, and stacking your frames.

A very useful tool, PixInsight’s dynamic background extraction tool helps remove gradients caused by light pollution or other environmental factors. Besides this, it has a gazillion other amazing processes that will be essential in your workflow.

I believe PixInsight is the most powerful software when it comes to editing deep sky astrophotography. It doesn’t have the friendliest interface, and it comes with a very steep learning curve, but it’s an amazing tool.

If you want to better understand the software and unleash its full potential, I strongly recommend you get the book Mastering PixInsight by Rogelio Bernal Andreo, as it will help you fully understand this advanced software option.

5. Astro Pixel Processor

Astro Pixel Processor (APP) is a relatively new entrant in the astrophotography software arena but has gained popularity for its user-friendly interface and powerful features. It is compatible with Windows, macOS, and Linux, and weighs in at EUR 165 plus VAT.

APP supports the processing of multi-channel images, including RGB and narrowband data, making it versatile for various imaging projects.

Similar to PixInsight, Astro Pixel Processor automates the calibration process, including the removal of biases, flats, and dark frames.

APP includes tools for accurate star color calibration, ensuring a natural and appealing color balance in your astrophotography; it is also an amazing tool for stitching panoramas of the deep sky.

6. Siril

Siril is an open-source, cross-platform astrophotography software that provides a range of tools for image stacking and processing. While it may not have as many advanced features as some paid options, it is a reliable choice for those on a budget or looking for an open-source solution.

Siril supports the calibration of images through the subtraction of dark, flat, and bias frames, ensuring the removal of unwanted artifacts. It includes automatic alignment and stacking features, making it suitable for both planetary and deep-sky astrophotography.

Advanced users can take advantage of Siril’s scripting support, allowing for automation and customization of the image processing workflow.

7. Maxim DL

Maxim DL is a comprehensive astrophotography software suite, covering everything from image acquisition to processing. While it comes at a higher cost (USD 249 to 640, depending on features), it is a favorite among professional astrophotographers for its robust feature set.

Maxim DL includes tools for camera control, autoguiding, and image acquisition, streamlining the entire astrophotography workflow.

The software offers advanced calibration options, allowing for the removal of biases, flats, and dark frames. Maxim DL features plate-solving capabilities, which can automatically determine the exact celestial coordinates of your images.

It also supports multi-filter set imaging, making it suitable for projects involving different wavelength bands.

Choosing the right software

With several choices listed above, how do you go about choosing the software that’s best for you?

The choice of astrophotography stacking software depends on various factors, including your level of expertise, budget, and specific requirements. Here are some considerations to guide your decision:

Budget

Some software options, like DeepSkyStacker and Siril, are free and open-source, making them ideal for those on a budget. However, paid software like PixInsight and Maxim DL often offer more advanced features.

Ease of use

Consider the user interface and ease of use, especially if you’re a beginner. DeepSkyStacker and RegiStax are known for their user-friendly interfaces, while PixInsight may have a steeper learning curve.

Luckily, there are lots of really well-made tutorials online that will guide your way.

Advanced features

If you’re an experienced astrophotographer looking for advanced features and capabilities, PixInsight, Maxim DL, and Astro Pixel Processor might be more suitable for your needs.

Compatibility

Ensure that the software you choose is compatible with your camera and other equipment. Some software may be more versatile in supporting various file formats, like FITS.

Community support

Look for software that has an active and supportive user community. This can be valuable when seeking advice, troubleshooting, or exploring advanced techniques. It is an aspect that might be ignored at first, but I believe it is extremely important.

In conclusion

Astrophotography stacking software plays a pivotal role in the journey of capturing and processing stunning images of the night sky. Whether you’re just starting or have years of experience, there’s a stacking tool that suits your needs.

Experiment with different software, explore their features, and find the one that aligns with your workflow and creative vision.

Remember, astrophotography is a blend of technical proficiency, creativity, and a deep appreciation for the cosmos. Armed with the right software, you have the tools to create breathtaking images that showcase the beauty of the night sky.

Clear skies!