- New UI with a single window
- New demosaicing algorithms, RCD is now the default one
- New algorithm to fix the AF square with XTRANS sensor (Kristopher Setnes)
- New support for FITS decompression and compression with Rice/Gzip and HCompress methods (Fabrice Faure)
- New support for quantization and HCompress scale factor settings for FITS compression (Fabrice Faure)
- New functions to extract Ha and Ha/OII from RGB images
- New linear match function
- New link command to create symbolic links
- New convert command to convert all files (and link FITS)
- New preference entries for FITS compression settings (Fabrice Faure)
- New native image format: 32-bit floating point image
- New native sequence format: FITS sequence in a single image
- New UI for sequence image list
- New zoom handing: ctrl+scroll (up and down) is the new way to zoom in and out
- New preview in open dialog
- New language selector in preferences
- New image importer: HEIF format
- New stacking filtering criterion (weighted FWHM). It can exclude more spurious images
- New macOS bundle
- New RL deconvolution tool
- New keyword CTYPE3 for RGB FITS in order to be used by Aladin
- New binary siril-cli to start siril without X server
- New preference entries with darks/biases/flat libraries
- New preliminary Meson support (Florian Benedetti)
- New ROWORDER FITS keyword that should be used by several programm now
- X(Y)BAYEROFF can now be configured in preferences
- Parallelizing conversion and some other functions
- CI file was totally rewritten (Florian Benedetti)
- Config file was moved to more standard path
- Optimization of several algorithms (Ingo Weyrich)
- Background extraction is now available for sequence
- Midtone Transfer Function is now available for sequence
- Fixed code for Big Endian machine (Flössie)
- Fixed bug in SER joining operation when Bayer information was lost
- Fixed a bug of inaccessible directories in MacOS Catalina
- Fixed crash on some OpenCV operation with monochrome images
- Fixed annoying error boxes about missing disk drives on Windows