computer science

Siril (software)

Siril (software) is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Siril (software) rather than just read about it. In short: Siril is a software application for astrophotography, which allows pre-processing and processing of images from any type of camera (CCD, planetary camera, webcam etc.). The images must be converted to 32-bit FITS format which is the format used natively by Siril.

Key takeaways

Siril (software) belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Siril (software) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Siril (software) from memory before moving on to harder problems.

Reference excerpt

Siril is a software application for astrophotography, which allows pre-processing and processing of images from any type of camera (CCD, planetary camera, webcam etc.). The images must be converted to 32-bit FITS format which is the format used natively by Siril. It is also possible to use the SER format (limited to 16 bits), generally used during "fast" planetary or deep sky acquisitions, without prior conversion. It is based on the GNOME environment and therefore can be run on many systems like Linux, FreeBSD, MacOS, and Windows. It is free software distributed under the terms of the GNU GPL.

History The project was launched in 2005 by François Meyer. Siril was initially developed as a clone of Christian Buil's IRIS software, in order to overcome the lack of astronomical image processing software under the Linux system; hence the name SIRI-L (IRIS for Linux). A new team took over development of the project in 2012 after a pause from 2007.

Features Siril allows the conversion of a large number of formats (images or videos) to FITS.

The calibration, alignment and stacking of astronomical images is done by navigating through the tabs of the "control center". However, an algorithm for the automatic detection and correction of defective pixels is available off the tab, in the Image processing menu. Since version 0.9.7, the global alignment which uses a recognized algorithm for this task has been added an optimization method thanks to the OpenCV library. In fact, Siril's automatic alignment allows to align images obtained with instruments of different focal lengths. Some image processing algorithms are available in the standard menu, such as Histogram Transformation, Color Calibration, and Banding Reduction Siril has a photometric analysis tool. Therefore, it is possible to study the transits of exoplanets, the variability of stars or even occultations. This tool requires the installation of gnuplot. Since version 0.9.9, the ability to create scripts has been integrated into Siril. All you have to do is drop script files with the .ssf extension in a folder named 'scripts' and whose location is defined in the program's settings. After a restart, a new menu entry appears and allows the execution of the installed scripts. Preprocessing + alignment + stacking can thus be fully automated. Since version 0.9.9, it is also possible to launch Siril through the console and run a script without the GUI. This can be useful when piloting a telescope remotely and only want to recover the pre-processed image. For example, entering the following command in a terminal runs the Processing.ssf script in the M31 images directory: siril -s ~/.siril/scripts/Traitememnt.ssf -d ~/Images/M31

Version 0.9.10 allows commands to be sent through one named pipe while logs and status can be obtained through another. The mode is activated the command line argument -p.

Since version 1.4, Siril provides the Drizzle algorithm for stacking monochrome and color images.

Native file formats

FITS Currently, Siril works internally with 32-bit FITS floating point images. Users can configure the program to work in unsigned 16-bit FITS format, in order to save computation time and disk space at the expense of image accuracy. Compression of FITS images is supported since version 0.99.4.

SER The SER file format is a simple image sequence format, similar to uncompressed movies. Files in this format, widely preferred by astrophotographers in planetary imaging, do not need to be converted and can be edited on the fly.

Screenshot gallery

References

Illustrations

Worked examples

Example 1 — a first encounter with Siril (software)

Start with the simplest possible case. Write down what Siril (software) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Siril (software) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Siril (software) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Siril (software)

In research: Siril (software) appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Siril (software) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Siril (software) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astrophotography, Cross-platform free software, Free astronomy software, so understanding it makes those chapters shorter.
In everyday life: Look for Siril (software) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Siril (software) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Siril (software) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Siril (software) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Siril (software) in simple terms?

Why does Siril (software) matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Siril (software)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Siril (software).