Sorry for my English, but I don’t know the language and I use a translator. I’m switching to Darktable from Rawtherapee because I’ve noticed that DT gives me better photos. I like them better and the “RGB color balance” module is fantastic. I have a question about focus. In RT, it was enough to turn on the “sharpen” tool and possibly increase the strength and the effect was very good. There is a diffusion and sharpening module in Darktable. I watched a few episodes but can’t figure it out to work on it. Too many sliders. Too much fun. That’s why I wanted to ask if the “contrast corrector” module will be a good choice for sharpening the photo? Is it rather not recommended? I haven’t seen any tutorial of anyone using this module
For diffusion and sharpening, you can just use a preset. I usually use a lens deblur, but there is also dehaze.
Hi @Damian_J,
Use duckduckgo and search for
darktable “contrast equalizer”
After that, search youtube for the same phrase.
Have fun!
Claes in Lund, Sweden
Use a preset of diffuse or sharpen and increase the iterations to increase the effect.
I don’t think I want to use the diffusion and sharpening module. It’s complicated. I wanted to know if a contrast equalizer module would be a good way to sharpen or add local contrast? I’ve seen a lot of Boris Hajdukovic’s videos on photo editing, but he doesn’t use this sharpening module. I wonder why? This module is simple and intuitive, and the results are quite good. Are there people who use this module at all instead of diffusion and sharpening?
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If you like it and have good command of it, then use it.
It works in LAB space and thus is prone to artifacts.
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I use the Contrast Equalizer for sharpening. Open the module, right-click in its controls, and select “deblur:fine blur:strength 3”. If you want to increase the effect, create new instances of Contrast Equalizer and repeat the same action. I do this as many as three times. You can try it and see if it meets your need.
Could you just boost the mix slider instead of the extra instances??
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Thank you. DT contrast corrector can cause artifacts. In fact, the RT sharpening module can also be prone to artifacts if I overdo the sharpening power 
For D&S module just stick to presets you will find one that is close and easy to modify… 2 new ones have been added recently as well for sharpening…
I often use the dehaze preset I like the amount of sharpening but it can boost noise in some instances if you are not managing that well. I also use the No AA filter preset and use 2 or max 3 iterations… I find if you go higher then the artifacts start… So those 2 are good and local contrast preset is also good… That one you can add a good few iterations to as well if you machine can keep up. there is a fast sharpen and now a sharpen and sharpen strong preset if you are on a new version of the code…
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Contrast and sharpness are related, but not the same.
Don’t worry about the diffuse or sharpen sliders. Start with the presets. I normally apply the local contrast preset, and, on top of that, add sharpen demosaicing: AA filter.
Later you can try more:
- speed: negative values sharpen, positive values blur
- 1st and 2nd order speed don’t increase noise (found this in one of Aurélien’s videos)
- if shadows turn black after sharpening, increase edge threshold.
- more iterations, higher ‘speed’ magnitude: stronger effect.
So, I start with the presets, and if needed, tweak them according to the rules above.know.
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Thank you for your suggestions. I will try to start with the presets in the D&S module, although I like to use the contrast equalizer module. It is simple and clear. I wanted to know its shortcomings and why it is so rarely used by users.
I use it because I understand it better than the D&S module. Yes, it works in LAB space and yes it can cause artifacts, but I have never had this issue because I don’t use high values for it. And no one should be trying to sharpen that much anyway because it invariably looks awful, just as it starts to look awful with D&S if you push it too far.
So, don’t be afraid to use the contrast equalizer. Push up just the far right for fine details, or push up the far left for softer contrast. You can get some really nice results with it once you figure it out, which won’t take long if you have an understanding of wavelets.
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Did you ever try ‘Contrast By Detail Levels’ in RawTherapee? Should do what you’re looking for, in combination with RL deconvolution, even more sharp.
hi @Damian_J the diffuse or sharpen module is great to use. It is very complicated and I I don’t understand all the sliders, but I have great success using just the presets. I apply sharpen demosaicing (AA filter) as my initial sharpening. This is sufficient on its own for a portrait. For images that I want more sharpening, such as landscapes, I create a new instance of diffuse or sharpen and use one of the lens deblur presets. The soft one is sufficient for most images but the hard one helps if part of the image is a little bit out of focus or a strong sharpening is needed.
The diffuse or sharpen module is too good to ignore. Just stick with the presets and accept the great results it gives.
Good luck with darktable. I chose darktable over rawtherapee because of darktables superior ability to localise adjustments through masks.
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Hmmm, I don’t know. When I learned that method of sharpening, the “teacher” said to do it with additional instances. It has always worked for me, so I’ve never looked into it any farther.
I still find a bigger problem is the actual preview. If you export your images and use no for high quality resampling it seems to be a more accurate representation of the preview. If you choose yes there can be sections with what appears to be more detail but the blacks seem to wash out a bit so perceptually contrast is reduced and to a degree the perception of sharpness. There have been issues many times over with people trying to assess noise and sharpness and having issues with the output not matching… so the issue extends a bit beyond even what tools you are using but what is the real truth of your selected sharpening/contrast adjustments… Taking into account issues that might be introduced around scaling and monitor calibration I am often not confident how my image comes across on other monitors wrt to color contrast and sharpness…
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Yes, the sharpening capabilities in Rawtherapee I have mastered. Currently I only edit in Darktable, because as I wrote above it gives me better results than RT. It also has a great masking tool.
Thank you all for your kind responses. The contrast corrector gives great results, so I will continue to use it. Of course, I will also try using the D&S module with presets. I’ll see what works better for me.
Just so I am understood correctly. I get better images in Darktable in terms of color and tonality than in Rawtherapee. That’s why I switched to DT. Focus adjustment in RT is not a problem for me
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