Edges-dedicated sharpening tool in DT

There is one fantastic tool in RT, called Edges. I use it especially for birds in flight, also tried on some trees, cables etc. landscape details. It’s absolutely halo-less. Pushed too much gives “oil paint filter” effect known from GIMP. But if used reasonably, it’s worth exporting TIFF from DT to RT just to use this particular tool.

100% crops. Not used, used reasonably and pushed to max:
lat1 lat2 lat3

Is there any way to achieve something similar using DT?

Here is description and some example https://rawpedia.rawtherapee.com/Edges_and_Microcontrast , they even posted a link to (nonexisting but archived) site with open code algorithm of this filter.

1 Like

How about the very versatile Contrast equalizer?

Have fun!
Claes in Lund, Sweden

1 Like

I have few modules in default style, just turned on with zero settings (to not search for them). Contrast equalizer is among them, I use it in every picture.

For sharpening detaily textures (like birds’ feather) it’s a perfect tool. I get more than expected, by setting different curves for luma and chroma.

But for sharp objects on soft background (like such lighthouse details on sky) i don’t have “initial idea”. You say that Contrast Equalizer can be mastered&tweaked to such purprose?
Shoul it be tweaked very steep? Let’s say high contrast for one detail level, but rest not as high? In separate instance of Contrast Equalizer module?

Normally, I use sharpen with a threshold in such cases. Contrast EQ, with the right frequency band selected, can also work well.
There was a thread here with a technique for sharpening edges (I have not tried it): Darktable Tricks

2 Likes

@Igor64 Test it!
Try all presets, one by one, to learn what the contrast equalizer module can do.
Drag the curves up – and down. That is the only way to learn how it works.

Try several instances of the module.

I have an X-trans camera. In many cases the denoise preset in the contrast equalizer module is sufficient; no need to invoke the denoise (profiled) module.

Have fun!
Claes in Lund, Sweden

High pass module with blending mode set to overlay

1 Like

Suggestion:

Enable Sharpen module, change blending mode to difference. Move radius slider until show edges. If is not enough to show edges, adjust amount slider until show others details. Come back blending mode to normal option.

1 -

2 -

3 -

1 Like

even in your “used reasonably” example I’m getting a strong oil paint filter feeling. I actually really like the way the untouched version looks to be honest lol.

the contrast equaliser is a fantastic tool though. I’m not sure how you would replicate that edges look from RT, but I pretty much always just lift the far right point of the contrast equaliser up (with a moderate to large selection area to also effect the adjacent point a bit) and it emphasizes the fine details in an image beautifully.

I do a lot of bird photography as well and on a related note, I’ve found that the capture sharpening in RT is far superior upon import than with DT. Fine feather detail always seems a bit blurry under DT and have yet to find a way to overcome that, although tools like the contrast equalizer can help a bit.

1 Like

Thanks for the compliment :+1: Convince the dt devs to port it to dt. The code is freely available and also not very complicated (~1000 lines):

1 Like

My pleasure. Perhaps I’ll submit a feature request to the DT team. Can you explain how the algorithm works? I’m comfortable with math but not so much in coding… Thanks!

1 Like

Yesterday I got much better results with Contrast Equalizer than before.

@judsonab will try more in evening. Sounds nice. First tries have failed as it produced halos every time.

1 Like

I will do that in PM to not hijack this issue.

1 Like

There is no such feature in darktable.

Yes, but would it make sense to add it, or something like it? Maybe I should raise the question in a new thread to avoid derailing this one

If you feel like you’d like to have it added, open an issue on github.

2 Likes