My hassle with signatures - please get that right in darktable and GIMP

I happen to publish a lot of my amateur photography. 90% of my pictures go from darktable GIMP, the latter is especially used for slight skin-healing and some dodge-and-burn. The GIMP doesn’t have a “signature” workflow, so I do that in darktable, where I saved a text, font, color, position and size as standard-setting.

Sometimes I need to turn the signature upgight, because I dont want to “tattoo” my name on the skin of a model - I need to cram my name-tag sideways and upright. For a reason that I can’t understand, there is no “lock” at 90°. I can spin the text around, but fixing it at 90° is pretty much impossible. Can you please add a “lock” or “notch” at that angle?

Sometimes I will be asked to deliver print-files, so I have to get rid of the signature. Unluckily I added that in darktable, so I have to get back to dt, export the file without signature and reproduce every step in the GIMP afterwards. It would be easier, if I could “sign” my photos in the GIMP (with a dedicated signature-tool, not using the text-window everytime from scratch). This way I’d save a “print” and a “signed” JPG.

You may say “oh Stefan, if you keep every XCF, the work can be easily reproduced”, but have you ever seen the sheer size of those XCF-files? I work on a notebook and I connect that to some external hard-drives in order to do back-ups. I skip the XCF format because it is too heavy on the disk-space, so I’d rather save two JPGs than a XCF plus JPG.

Are you talking about the rotate slider in darktable’s watermark module? You can just enter 90 there, no need for any lock.

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This is not something I do, so I could be wrong, but couldn’t you create a separate JPG containing the signature on a transparent background, and just drop it on top of your photos?

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Make your feature request in the right place:

This IS something I do for my various overlays on my YouTube videos. Just create one or two xfc files with a transparent “signature” in horizontal and vertical orientation. When you want to work in GIMP, open up this xfc, and “paste as layers” the image you want to add. Move the signature layer to the top, you are done. Easy peasy.


This could be something you can theoretically script and bind to a hotkey if I’m not mistaken (@Ofnuts does something like this already exist?).


  1. Open (as a layer) a PNG saved on your machine somewhere.
  2. Move to the top of the layer stack.
  3. Make active (so you can immediately move it around, rotate, whatever).

Then it should just be a keystroke to invoke the script and automatically place your signature.

Also, if you save your signature/watermark as a transparent PNG file somewhere, you can also just drag and drop it over your canvas in GIMP.

You could even got a step further and save a couple of different versions of your watermark, normal and rotate 90° in both directions - then just choose the one you want.

[edit] - there’s also a thread here where we looked at doing this bulk with imagemagick - so if you wanted to automate it further you could possibly try on of these:

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I’m afraid I can’t punch in any number. The only way is to move the little marker - and that’s not precise at all.

I’m not a fan of watermarks, and luckily, a few people came up with this: Annotation with Imagemagick (Watermark -ish)

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In Darktable you can right-click in “rotation” and then write a 90 (This method works in every slider of this kind).

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Oh man, that is non-obvious, but awesome to find!


Plenty of signature scripts around, but none that does a stylish signature worthy of a member.

Personally, I sometimes put a logo in a corner, it is just a PNG with some transparent margin, to add it with Gimp, File>Open as layers, View>Snap to canvas edges (or Alt-Ctrl-E), and then drag the image to one corner where it will snap. Using a script would entail about as many clicks…

I just tried that for the first time. Daktable-user since 2011 and today I already learned about the right-click in the modules. Gosh - my learning curve is steepening-up at an awful speed.


The custom slider widget is by far my favorite darktable feature, but I fear that it is not easily discoverable by new users who are accustomed to traditional sliders. @houz should consider adding a dedicated section to the DT site for the slider at least.


The original blog post that introduced them: bauhaus widgets | darktable

The usermanual page about them:

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For convenience of those that follow this link, the first of the five mentioned ways of interacting with these sliders is incorrect.

And @houz has the documentation fix in the pipeline:

Now this little tidbit is worth it’s weight in gold! Been using dt for a few years now, and never knew about this. And I swear I even read the manual and everything! :rofl: