Feature request: Add several dark frames

In the current version (RT 5.8), an average over several dark frames can be used only if one chooses Auto-selection in the Dark-Frame section of the RAW tab. If I want to use dark frames only for one picture (for instance, because I took night-sky pictures at -10 degrees and have 10 dark frames for this specific setting), I can select only one single dark frame in the RAW tab. It would be great, if I could select several dark frames here, which are automatically averaged and used as one master dark frame.

Best regards and thanks for a impressive software, Andreas

As a workaround, you could probably average the darks in Siril and use the averaged frame in RT.

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This feature has been proposed a long time ago. The only thing that is missing is someone with enough time to implement it.

I see: thank you, both, for your replies. Siril definitely works, I use it already. Nevertheless, maybe someday someone will find some time to implement the feature.

Maybe to simplify the development of this feature in RawTherapee, what could be done is to check if siril is available and if so, copy the files in directory, call siril headless to convert them and stack them and use the result in RawTherapee. Siril can execute commands from a named pipe or file or stdin.

I thought, stacking is already implemented in RT, when automatic dark frame selection is selected and more than one fitting dark frames are found: than the found frames are averaged. Nothing more is necessary, right?

Use Siril to stack your raw dark frames then export to tiff. Use imagemagick to convert from the SIRIL produced tiff to dng, using the command

magick stacked_dark.tiff stacked_dark.dng

Then use exiftool to copy the tags from an original file with the same exposure settings to the new dng to finish the process

exiftool -tagsFromFile direct_from_camera_raw.RAW -x BitsPerSample stacked_dark.dng

Then in the file browser for selecting dark frames, go to the bottom right corner and switch from “same as current photo(RAF)” to “All files”, and your fake raw dng should appear in the directory.

Note that that approach may not work quite correctly. There are some subtleties regarding subIFDs that will cause something that only had tags copied using tagsFromFile to not get recognized as a valid DNG.

I’ll try to find an example of my DNG tagging command line somewhere.

The above works for me, at least with Sony A7ii raw files. Did you have any occurrences of tagsFromFile not working?