Siril is powerful astronomical processing software used by new and veteran astrophotographers. Siril has many tools and features that make it ideal for processing your astronomical images.
In this article, we will explore the capabilities of Siril, its key features, and benefits for astrophotographers. We’ll also discuss how to enhance your experience using Siril Scripts for automation and efficiency. From preprocessing to advanced image processing techniques, we’ll guide you through the process of producing stunning astronomical images with ease. With step-by-step instructions and helpful tips, you’ll be on your way to mastering your astrophotography skills in no time.
About Siril
Siril is powerful software for processing astronomical images. It’s free and open source, which means that it has a sustainable future, making it a good platform to use for post-processing your images in the long term. Siril offers a broad range of algorithms and features that include stacking, color calibration, noise reduction, cosmetic correction, deconvolution, background extraction, and for even more advanced uses – Pixel Math.
When you first look at Siril, its user interface seems to include a lot of different functionalities, and this is true. Siril works based on the concept of a home directory – this is the directory where you store your input files and the location Siril uses to store its output files. Once set, your home directory becomes the default and you typically have a home directory for just one object; meaning, you have a separate home directory for each object you intend to work with.
Siril uses a set of conventions for its output files and you need to be aware of the prefixes it uses for its processed files.
Fortunately, Siril includes a powerful scripting language that allows developers like myself to automate Siril. Automating preprocessing tasks offers numerous advantages that can significantly improve your workflow and the quality of your final images. Here are some key benefits:
- Time-saving: Preprocessing can be a time-consuming process, especially when dealing with multiple files. Automation simplifies this process by executing repetitive tasks quickly and efficiently, allowing you to focus on other aspects of astrophotography.
- Consistency: Automated preprocessing ensures that every image undergoes the same set of operations, maintaining consistency across your dataset. This results in more accurate stacking and calibration, ultimately leading to better image quality.
- Reduced errors: Manual preprocessing is prone to human error, leading to inconsistent results or even damaging your data. Automation eliminates these risks by strictly following predefined steps.
- Streamlined workflow: An automated preprocessing pipeline reduces the need for manual intervention, resulting in a smoother and more efficient workflow. This allows you to dedicate more time to capturing stunning astronomical images and refining your post-processing techniques.
- Ease of use: Once scripts are set up, automating preprocessing tasks becomes a simple matter of running the script with your input files. This minimizes the learning curve associated with mastering complex software tools and makes it accessible even for beginners.
By adding automation to your astrophotography preprocessing, you can save time, reduce errors, ensure consistency, and improve your images and overall experience.
Getting Started with Siril Automation: A Step-by-Step Guide
In this article, I walk you through acquiring and installing two scripts that you can use to pre-process your calibrated LRGB and One-shot-color (OSC) FITS files that you acquire using services like Slooh.com, iTelescope.net, Telescope Live, and other remote telescope service providers. When the scripts finish executing, the final image is left open in the Siril interface for you to continue processing in Siril and a file gets saved in your home directory that’s usable by other astronomical processing software.
I assume that you already have Siril installed on your system. If you don’t already have it installed, the process is straight-forward: simply point your browser to https://siril.org/ and download the installation package for your operating system – Siril supports Linux, macOS, and Windows.
Once you have Siril installed, start it to ensure that it works as expected – starting Siril is enough for now and you can exit Siril by pressing CTRL/CMD + Q on your keyboard, or simply close the window.
Acquiring and Installing the Pre-processing Scripts
Use the following steps to download my pre-processing script:
1. Download the following ZIP file and save it somewhere convenient on your system: Siril_PreProc_Scripts
2. Open the ZIP file and review the ReadMe.txt file – it contains an overview of the scripts along with installation and usage instructions
Using the Pre-Processing Scripts
There are two pre-processing scripts in the ZIP file:
- ErikWestermann_LRGB_PreProc.ssf – this script stacks and combines calibrated LRGB FITS files and produces a pre-processed RGB file that includes the L component; the file left open in Siril is ready for further processing within Siril or any other astronomical software.
- ErikWestermann_OSC_PreProc.ssf – this script stacks and combines calibrated OSC files and produces a pre-processed RGB file; the file left open in Siril is ready for further processing within Siril or any other astronomical software.
To use the scripts, first figure out whether you want to process calibrated LRGB or OSC data. For Slooh.com missions, OSC data is indicted by “_m_cal.fit” at the end of the filename.
Refer to the appropriate section that follows for directions on how to use the script.
Pre-processing LRGB Files
If you don’t happen to have any LRGB files to work with, download the sample observation of Messier 20 from the Downloads page on this website. Here’s a direct link to download the observation (116 Mb): Download sample observation of Messier 20
Use the following directions to pre-process LRGB files:
1. Create an empty directory somewhere convenient on your system; this will become your home, or working, directory
2. Copy the your calibrated LRGB files to the new folder
3. Create four new folders named L, R, G, and B (this must be in upper-case and are just one letter each)
For each of the following four steps (4-7), ensure that you have at least two files in each folder; if you don’t have two files, simply make a copy of the file you have so that you have two files.
4. Move your luminance files into the L folder.
5. Move your red files into the R folder.
5. Move your green files into the G folder.
6. Move your blue files into the B folder.
7. If it’s not already running, start Siril (ensure that you followed the installation instructions in the ReadMe.txt file included with the scripts in the ZIP file)
8. Set your home folder by clicking the third button from the left, at the top of the Siril window (it looks like a white house on a blue background); select the folder you created in step one.
9. Start the ErikWestermann_LRGB_PreProc script by selecting it from the Scripts menu; the process will take some time to run and may take a while if you have a lot of files.
When the script finishes, it leaves open the combined RGB image on your Siril desktop and it has saved this file as ‘unstretched_lrgb.fit’ in your home folder.
From here, you can continue processing this sample image to produce a final result; refer to this article for the steps to follow if you’re using the sample observation of Messier 20.
Pre-Processing OSC Files
Use the following directions to pre-process calibrated OSC files:
1. Create an empty directory somewhere convenient on your system; this will become your home, or working, directory
2. Copy the your calibrated OSC files to the new folder
3. Create a new folder named ‘lights’ (without the quotation marks)
4. Move your OSC files into the lights folder. Note that you must have at least two files; if you don’t have two files, simply make a copy of the file you have so that you have two files.
5. If it’s not already running, start Siril (ensure that you followed the installation instructions in the ReadMe.txt file)
6. Set your home folder by clicking the third button from the left, at the top of the Siril window (it looks like a white house on a blue background); select the folder you created in step one.
7. Start the ErikWestermann_OSC_PreProc script by selecting it from the Scripts menu; the process will take some time to run and may take a while if you have a lot of files.
When the script finishes, it leaves open the combined RGB image on your Siril desktop and it has saved this file as ‘unstretched_result_xxx.fit’ in your home folder, where xxx represents the total exposure time.
From here, you can continue processing this sample image to produce a final result. Refer to this article for the steps to follow using the sample observation of Messier 20.
Bonus Script
I include with your download of the Siril scripts, a third script that performs complete processing, where you end up with an image that’s ready for sharing. Refer to this article about how to use the script.
Conclusion
In summary, by leveraging the power of Siril and its automation capabilities, you can significantly enhance your preprocessing workflow for astrophotography. The provided scripts for LRGB and OSC data are designed to streamline the process, ensuring consistent results and saving you valuable time.
Remember that practice makes perfect—keep experimenting with different settings and configurations to discover what works best for your specific needs. By doing so, you’ll be well on your way to producing stunning astronomical images that showcase the beauty of our universe. Happy stargazing!
