Darktable to GIMP workflow question (open as layers, auto-align)

I am relatively new to the whole FOSS scene, but I’ve tried to really dive in. Despite that I find I don’t know how to do certain things, which seem like they may already be supported. Furthermore, searching for those proved rather unproductive. So here I am. Thanks to all at PIXLS.US though, I’ve found this site a tremendous help as I make the switch.

I have a particular workflow I used to use in LR/PS that was highly automated, however I have been able to break that up in to individual steps, because the automation does not yet exist in the FOSS world, to my knowledge. The following bits of that workflow are what I am wondering about.

I have selected 20 (or more/less, the point being it can be a fairly high number) images in darktable which I would eventually like to open as layers in GIMP

  1. I know there is a way to open images in GIMP via darktable, I have installed a lua script to do so, however, I am unsure of a way to command they be opened as layers in a single project. Is this possible and I am missing it?
  2. Within gimp is there an automated/quick way to combine all open images into a single image as layers? This would then allow me to send all images to gimp via dt, and then have gimp reorganize them all as layers instead of individual images.

All these images are Astro-landscapes, I would intend to mask out the foreground in the hopes of using an auto-alignment tool that could then align all the “sky” images so a median stack mode could be applied to them. I would do a similar thing for the foreground as well, then later mask the two median stacks together for a final astro-landscape image. My question in regards to this revolves around the image-alignment. How can that be done? I have seen mention of people using hugin (which I’m familiar with as I use it heavily for enfuse on my day time landscapes and panos). However, seeing as I want to mask out the foreground to ensure the stars get aligned properly, not the foreground, there starts to be a lot of overhead in the workflow if I had to send them to hugin after masking each. I’d like to stay inside gimp at this point if possible, and it seems likely to me gimp already supports this. I’m just not familiar enough with it.

I apologize if this should be obvious to me. I have not had as much time to play around and experiment as I would like.

Thanks to all.

@BzKevin Welcome to the forum! I was a newbie not long ago. Here are some links to get you started:

I’d just export them all in one go from darktable, then start GIMP and open them as layers. You can select more than one file in the open dialog there.

@BzKevin - first of all, welcome to PIXLS.US!!!

In order to provide some help, it would be really useful to have a minimal example of a “typical” image stack you would like to process. I think that for a proof-of-principle three images would be enough. It would also be useful to know which operating system are you using, as solutions might be different depending on this…

In the past I tried myself to do some alignment of astronomical pictures, and what I realized is that the alignment works better when the dark areas of the image are converted to pure black. This allows to avoid associating control points to sensor noise, and lets the alignment procedure to focus on bright stars.

Also, if the images to be stacked are very similar it is probably possible to apply the same foreground mask to all of them, thus reducing the amount of hand work needed for the processing…

Anyway, I’ll be glad to give you some help!

Certainly, the mask would be generated on one image, then copied to all the rest.

I am running Ubuntu 16.04

Here are some sample images, Tiff’s are just darkroom exports of the .CR2s. The “Beach Vertical” is the results of stacking 20 or so images in the manner described above (when using different software than I now use…).

Let me know if the link below doesn’t work for you.


This thread is very similar to what I want to do as well. However, I feel as though I am placing more emphasis on foreground than was done in this post. The images I provided aren’t the best example of this, but they were readily available.

I can find lots of options out there for aligning/stacking images containing sky only, but finding one that allows you to define a sky region and a land region so that it handles them differently has been impossible to find. On windows I used Sequator, which was a handy tool that automated this process. Mac has a similar program called Starry Landscape Stacker. I was hoping I could get down the workflow in gimp, and then eventually work it into a semi-automated script.

However, I’m not having a ton of luck. I was able to get OK results by remapping the images in hugin to get their alignment close (it didn’t seem to get them all perfect for a stack of 20). Then I opened these as layers in gimp and manually fixed any alignment issues. Finally I individually changed each layer’s oppacity to emulate and averaging filter, because G’mic seemed to be treating my layers as though I hadn’t gone in and manually fixed their alignment when attempting their Layer (Median) filter.

I hope to keep playing with things as I have time. I’m sure there has got to be a good way to do this. I just don’t know my way around the tools well yet.

Welcome, from newbie to newbie.
In regards to star alignment, I would try this if you’re on Linux, or DeepSkyStacker, if on Windows.
I’ve never used Freeastro, but did some experiments with DeepSkyStacker for the sky, then merge it with the foreground in PS.
But I’m also new to FOSS in photography, so there should be more to come.

how do you export them? i can not export raws in darktable and i can not import sony raws to gimp 10. i basically have to work with 8 bit jpegs

thanks, D

You should export 16 or 32 bit tiffs from darktable and open the tiff in gimp.

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