Optional dependencies are:
- libcurl OR glib-networking with its HTTP backend for online operations like update checks, astrometry and photometry requests.
- libraw, libtiff, libjpeg, libpng, libheif for RAW, TIFF, JPEG, PNG and HEIF images import and export. The libraries are detected at compilation-time.
- FFMS2 for film native support as image sequences. It also allows frames to be extracted from many kinds of film, for other purposes than astronomy. Versions < 2.20 have an annoying bug. It is recommended to install the latest version.
- ffmpeg (or libav), providing libavformat, libavutil (>= 55.20), libavcodec, libswscale and libswresample for mp4 sequence export
- gnuplot for photometry graph creation (not required at compilation time)
- wcslib for world coordinate system management, annotations and the photometric color calibration
- libconfig (Structured configuration files support), used to read the configuration file from versions up to 1.0, only used to get old settings now
- libjson-glib for update checking (useless if you build an non-released version).
- Exiv2 to manage image metadata.