I have been working on a Linux preprocessing utility for about two years, primarily for my own use as an educational tool and the essential ingredients, curiosity and fun. Now in its fourth iteration, it is a more functional package with a new name features and interface.
Noted: there are plenty of excellent preprocessing programs out there... and I use PixInsight for many tasks. I am just sharing what I have been doing in astrophotography - DIY software.
Primarily intended for consumer digital camera RAW data, the
Asterism user manual explains far more than I should include here.
Asterism is a bash script that performs a number of tasks more clearly arranged in a tabbed user interface - compared to previous versions.
Asterim uses existing programs to do the preprocessing work. Yad (GUI) ImageMagick (Q16) and Panotools are required. Hugin MacroFusion and Enfuse are optional. Note: libtiff should be installed on most Linux distros - if not it is also a requirement.
Asterism's primary function is preprocessing. That is image reduction / calibration deBayer alignment and stacking. Secondary processes are stand-alone image calibration, without alignment and stacking. Master frame creation. Conversion (16 bit monochrome Bayer) - not that useful unless you have special requirements.
There are range of other options, again better explained by viewing the documentation and playing with a small image set to illustrate the various functions.
Not much more to say on the topic. It's a work in progress, but functional, all the same.