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Siril was meant to be Iris for Linux (sirI-L). It is an astronomical image processing tool, able to pre-process images, stack images and help aligning them manually. It is thus well fitted for amateur astronomers having a low volume of images and bad quality images that automatic tools fail to align properly. Sourceforge project and website are old and unmaintained.

The software is being updated to recent operating system libraries (mainly to GTK+3) and still under high development and unstable. This page is the temporary Web page for Siril's new version. Hopefully in the near future the sourceforge page will be updated to add the same information.

Siril's works internally with FITS images, unsigned 16-bit for each pixel information. All images you want to process with Siril thus need to be converted, see the stacking tutorial page.


New features are being introduced quite regularly. Usual software features are explained with screen captures on the stacking tutorial page, and main features are:

  • Native image format support
    • unsigned 16-bit FITS files
    • SER files
    • AVI files soon
  • Image conversion (to the native FITS format only)
    • Supported input types: 8-bit BMP, short movie files (like .AVI), NetPBM binary images, RAW images (.CR2 and .NEF for now).
  • Image registration; supported methods:
    • Translation for one selected star alignment using FFT. This is not working fine at all.
    • Manual translation with two preview renderings of the current image with reference frame in transparency.
    • Image rotation is not implemented yet, but is under consideration.
    • Using Theli is considered too, to align frames with a map (fixes image distortion, rotation, translation, according to many stars referenced by astrometry data).
  • Image stacking
    • Summing and median stacking.
  • Pre-processing of images with multi-channel offset, dark and flat images.

Status of the new version (TODO and BUGS)

Dec 2, 2012: Version 61 begins the support for SER files (a frame sequence container) native use.

Oct 8, 2012: Version 54 is the first version actually able to stack (manually-)aligned images.

The best information is available in the SVN log. A file is also available on the SVN, TODO, that has a more precise list of things to do and known bugs.

  • Only color images and movies have been tested for now. Movies with numerous frames will require several GB of storage for now, since each frame is written to disk with a 16-bit pixel depth.
  • Only 3-channel colour images assigned to R, G and B are possible. Other assignations are to come, for LRGB or narrowband composition
  • Command line has been deactivated
  • FWHM function does not work properly (badly implemented, soon fixed using astrofocuser's code)
  • Automatic translation registration is not working well, but manual alignment can be done in a convenient way
  • Warning: RAW images appear darker than in rawstudio or other RAW images visualisation tool because no automatic color and gamma correction are used
  • Siril has light and contrast levels control with the common hi and lo cursors, but no gamma correction or other non-linear scaling is available
  • Median stack is limited to 50 frames to limit out of memory likeliness
  • 16-bit BMP import fails

Compilation and installation

Siril is currently only released as source from its subversion base. There is a package for the Arch Linux system, built from the source, in AUR. For other OS, you need Subversion (svn command) to retrieve it and autotools and gcc to compile it. Mandatory dependencies are gtk+-3.4, cfitsio and fftw. Optional are dcraw and mplayer for RAW and AVI conversion, and can be installed after Siril's install. The address of the SVN base is:

(sorry for the bad certificate - this URL does not work for online souce viewing with old web browsers). The source is read-only if you have no particular authorization. If you want to participate to Siril and be able to commit on the svn, send a message to user Vincent here.

Once you have got Siril's source code, it's easy to install it. Siril is managed with autotools, so it's simply built using ./configure and make. If configure has weird errors, try running:

$ aclocal && autoconf && autoheader && automake --add-missing

before retrying it. To install Siril, use the usual:

$ make install

Default installation directory is probably /usr/local. To launch Siril, the command name is siril.