New features are being introduced quite regularly. Here is a list of main features:
- Native image format support
- Unsigned 16-bit and floating point 32-bit FITS files (other FITS are converted to this format on-the-fly)
- SER files and FITS cubes for one-file sequences
- AVI and many other film files, their support is being dropped in favour of SER.
- Image conversion (to the native FITS format only)
- Supported input types: 8-bit and 16-bit BMP, TIFF, JPEG, PNG files, NetPBM binary images, RAW DSLR images.
- Pre-processing of images with offset, dark and flat images, cosmetic corrections and synthetic offsets
- Image registration; supported methods:
- Global star alignment, based on star detection and matching using a variable number of degrees of liberty
- Translation using DFT centred on an object, generally used for full-image planetary images
- Translation using PSF of a single star, generally used for deep-sky images or photometry
- Manual translation with two preview renderings of the current image with reference frame in transparency
- Registered sequence export
- Supported export file formats: Siril FITS sequence, SER sequence, uncompressed AVI files, GIF up to 0.9.4, MP4 and WEBM web publishing video formats since 0.9.5
- Optional cropping, resizing, linear pixel value scaling and normalization of the exported images
- Image stacking, with optional additive or multiplicative normalization
- Summing
- Median
- Average with rejection (percentile, sigma, median, MAD, Winsorized, linear fit and GESDT clipping)
- Pixel minimum or maximum across images
- Enhancement and processing of final images
- Visualization only: lightness/contrast cursors, scaling modes (linear, log, square root, squared, asinh, histogram equalisation), negative and false colour rendering and clipping
- Background gradient removal tool
- Cosmetic correction tool
- Colour calibration, manual or automatic using photometry after plate-solving
- Deconvolution
- Histogram transformation
- A command line for various processing functions, available from the GUI or from a command-line version of siril, see the list of available commands.
- A star finding algorithm with PSF information
- Image compositing tool, combining and aligning multiple layers (2 to 6) with custom colours into a resulting image, with luminance layer support
- Plotting various pieces of information about an image sequence (FWHM, star roundness, periodic error of the mount, amplitude, background level...) and using the plots to filter out images from a sequence for stacking
- Pixel math to combine images using math formulas