I was testing a workflow for doing timelapses with my GoPro Hero 4 (JPG-only), so I thought I could share here what can be done staying fully FOSS:
License: CC BY-SA 4.0
The process:
- the images were imported and renamed with Rapid Photo Downloader
- unfortunately I forgot to turn off my backyard’s light and this confused the auto-exposure. I used timelapse-deflicker to minimize the problems, any flickering left I suspect it comes from passing cars
- I used darktable to batch-edit the images, dividing them into three sections: sunset, transition, and night
- sunset: only denoise
- night: denoise, +1 eV exposure (limited to the dark areas with a luminance mask), color balance with input saturation down to zero and some blue highlights added (borrowing the idea from the low light module). I had to do this because the backyard light gave an awful yellow color to the leaves, and also because the exposure mask artifacts were better hidden in B&W
- transition: I used dtlapse to interpolate exposure and color balance between the other two regions
- the darktable-exported images were imported into Kdenlive, I added some simple in and out transitions, and exported an MP4 video
- finally, I used Exiftool to add XMP metadata to the video file
All of this under Kubuntu 20.04
Software things that could be better:
- darktable’s auto mode in the exposure module only works on RAW, not on JPG. This would have avoided the use of timelapse-deflicker and the doubling of disk space needed during edition, and I think that maybe auto-exposure + dtlapse would have done a better job with the deflicker
- the low light module would be a nice addition to dtlapse
Although it was just a test (don’t judge the artistic quality of the video 
), I quite like the end result and ended up learning a lot for next time.