I had a go with Siril as it can apparently handle the raw files that Fujifilm cameras create. I'm not keen on the tonnes of .fit files it creates at each stage, but they can be deleted manually.
I followed the tutorials on the website after trying to muddle my way through and I've got to something I'd like to export to process further.
But I can't seem to do so. Saving the RGB image to a tif results in some unusable kaleidoscopic mess. Saving to jpg results in a nearly-all white image.
So how does one actually export a usable or indeed viewable image from Siril?