I often hand held shoot very high ISO images to capture subjects in ambient light. High ISO causes random noise. One way of reducing this noise problem is to merge/stack multiple captures of the same shot. But because a tripod is usually impractical it means handheld shots need to be aligned.
There are numerous programs that offer this capability but I don’t believe Darktable has that ability. I am wondering if this is an improvement that a developer might be interested in investing time in. Possibly the composite module could be tweaked to offer auto align.
I know as a user it is easy for me to ask for a feature, but I do appreciate that people volunteer their time and I can not expect my wishes simply to be granted because I ask. But maybe one of the developers sees value in my request and could invest their energies in this idea. If not, I understand. Thanks
This is something I would find useful, and is an area where open source tools are somewhat fragmented. The underlying algorithms are well understood and implementations are available in Hugin. This is far from ideal as it usually means a bulk edit in DT => Hugin => GIMP for averaging/compositing.
If DT is not appropriate then getting the capability natively in GIMP would be a next best think (modeling the equivalent capability in Photoshop to open a bunch of photos as layers and auto-align).
Not an expert in this, but afaik focus stacking can be done with enfuse for which there is a LUA script. Now the 1 million dollar question is, if that can be combined with the image registration.
There is a lua-script, contrib/image_stack, the aligns the images and then stacks them using 1 of 12 different methods supplied by imagemagick. This form of stacking is not for HDR or focus stacking. It does work really well at noise reduction. My test set was a 12 image high iso set shot handheld. The resulting image was aligned and almost noise free. The inspiration for the script was https://patdavid.net/2013/05/noise-removal-in-photos-with-median_6/
If you want to do focus stacking, then contrib/enfuseAdvanced is your best bet. You should read the enfuse documentation to understand the settings for achieving the best results. enfuseAdvanced also does image alignment.
I really want to be doing this image alignment in DT so that I can then process the image in a single program. Based on the PR it looks not far away for DT. As for focus stacking that would be a bonus, but editing the individual frames in DT and then focus stacking would be practical. However, I might need focus stacking less now I have my tilt macro lens
I think enfuse is a pretty decent program for exposure averaging to reduce noise. It works well. But for focus stacking, it works poorly. It too often has halos regardless of the options tweaked and it’s not as good as Zerene or Shine Stacker, the later of which is open source.
