Tone equalizer problem

why is histogram shrinked on Tone equalizer for some pictures (mainly JPGs)?
It shows -1.3 EV for almost black tree! I am not able to increase brightness on the tree, without increasing overall brightness.
It is nicely possible in old not recommended Shadows and Highlights, but not in new Tone equalizer.

Do I miss anything?
Thanks for help

P.S.: Darktable 3.0 on Windows 10

Take a look at Aurelien Pierre video on tone equalizer.
But basically, that histogram is not the image histogram, but the blur mask histogram used by that module. In the mask tab, you can tweak the exposure and contrast sliders to get a more spread out mask histogram. Again, this is shown in that video in details.


Those two aren’t the same kind of histograms. The top right one is the histogram for your image and the one in the tone equalizer is for the mask in the tone equalizer. Not the same thing!

Have a look at B. Williams video about this module:


Go to the masking tab, adjust mask exposure comp. so that the line is in the middle, then adjust contrast to adjust the span, be sure there’s no orange. This does not affect the image, only the equalizer histogram so that it’s using the full range. Then adjust it to your needs.

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if you disable guided filter then the histogram is similar to the main histogram (depending on the rgb to luminance setting).
If you disable “guided filter” the tone equalizer behaves as a bunch of exposure correction using parametric masks for several luminance ranges.

Yup. Probably this playlist:


this video in particular:

and this:

Honestly it’s one of more powerful modules but requires a bit of watching and learning :slight_smile:

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Agreed, but I do find that I have to do a lot of back and forth fiddling with the mask exposure and contrast compensation sliders in order to get a properly spread and centered contrast mask. I’m also still trying to understand how mask should look like when displayed

But it is a great tool to work with.

Yeah, it was like that for me too. Basically mask should be smooth over fine details, but follow edges.
In Aurellien’s video you can see him working on very though picture of a dog with sunlight in full view in the background and that part gives detailed info about tone equalizer’s masks and their look. Also you’ve gotta take into account any exposure corrections done previously and thus requiring you to adjust masks etc.

Another thing to note, but IMO very important one: While tone equalizer is great tool when it’s needed, it’s not a “universal” module. Some pictures just do not need to be messed with in a way of tone equalizer :slight_smile:


It took me a few hit and misses before I realized this. I get the impression that the wider the dynamic range the more you need to use the tone equalizer.

For those people that want to have a go at the images that Aurélien Pierre uses in his video’s: I looked them up when he posted his video (all of them are here on

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Yep, and sometimes I get better and faster results by using the exposure module with a simple parametric mask. Especially when the Tone Equalizer starts crashing DT… but that’s a different story. :wink:

Sometimes I wonder if a web page tutorial with some use cases would help some of us get through the learning curve

And that really depends.

I think @anon41087856 did an awesome job with his darktable 3.0: video series and it’s a bit more “edible” than say 50-pages long essay/tutorial on whys and hows and ins and outs of tone equalizer.

However some people who would bail out on 1.5h long video would gladly read that 50-page long essay/tutorial… It’s all about choosing what to focus on. IMHO - videos are great way and get 80% of cases. For those needing reading material instead - maybe somebody will take a task and do it, like for example translating Aurellien’s article:

PIXLS.US - Darktable 3:RGB or Lab? Which Modules? Help!


As mentioned by me and @johnny-bit in this thread: There is really good material out there (out here at mostly).

But nothing beats loading an image an having a go at it (probably multiple go’s :wink:) That’s when you specifically run into things and can go back to the articles/video’s to get the answer(s).

I love to copy and play with the examples that are shown in the video’s (hence my search for the images used). I think it took me about 4 hours to watch/copy/play AP’s tone equalizer video.

One thing that I still don’t really get is the luminance estimator setting. The video and the pop-up shown talk about choosing the one that gives the highest contrast: That is always the RGB sum setting. When to use the other ones? And why is RGB euclidean norm the default if the hints point to something else?


I hear what you’re saying, there’s plenty of people with good ideas but never willing to take them on. For my part, I would try to put something together, but I’m a beginner at best, and my only language skills are English and math.

For the record, Aurelien’s videos are outstanding, and I’ve gone through them as well as his white papers, his “which modules help” and also Bruce Williams’ tutorials as well. So I’m not knocking anyone’s effort… What I’m suggesting is that something like Pat David’s GIMP tutorials could help bridge the gap between the concepts and the “button-ology”

That’s what I have ultimately done and finally got to the point began to see the forest from the trees, and found that the fundamental concept was pretty easy… once you get past all the different settings and they way they interact with one another.


Thanks all for hints, now I understand difference between picture histogram and mask histogram in the Tone EQ:) It means I am able to get similar results with Tone EQ and Shadows&Highlights (ok, sometimes better).

And that’s my biggest concern now with Darktable, all these new tools (ToneEQ, Filmic, ColorBalance) are very powerful, but to get the same result involves much more playing, attempts and experience against ´´classic´´ straightforward workflow with curves, saturation, sharpening etc.

It reminds me, why to have car with simple steering wheel when I can have plane cockpit to be able to turn left.

It is just my opinion, but main idea should always try to follow KISS principle and go into more complex stuff just in case there is no other option!

If you don’t agree, try to get similar results on picture with old/new workflow (tools) and we can compare costs (number of steps, time, complexity) vs benefits (simplicity, ease, quality).


This is just the cost of learning a new tool. Once understanding is achieved, the new tools are quite efficient.

The “classic” tools were not easy to learn either, its just that we have been using a tone curve for like 25 years.

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Oh my godness how true. I recently had a convo on reddit where a person claims that darktable is simply unintuitive and ignores “well-established standards” (as if something like that exists).

And quotes like that make me a bit angry. Previously I symphathesized with “a bit harsh” replies from Aurellien, now I completelly agree with all Aurellien’s critiques about users :wink:

Well, honestly some tools do need more options. Have you seen video editors? Those aren’t dumbed down at all, yet allow editors to edit, colorgrade etc whole freaking movie (standard movie has ~24 frames per second and is say 2h long - that’s roughly 172800 RAW frames to edit :scream:)

As for your challenge - I checked. I re-edited my edits and to my amazement it’s faster with better results, less halo-ing etc :stuck_out_tongue: linear editing for teh win :stuck_out_tongue:

AMEN :pray:

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Around 2002 I took an “Photoshop for photographers” class and watching people struggle with the tone curve was interesting. Even after a 2 hour lecture on jus the tone curve, the whole class working on the same image, a Q&A session, about half the people didn’t get it.

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I must admit that Tone curve example was not the luckiest choice:)

I have experience with Video editors and for example with Color corrector in Vegas I am simply able to do white balance even some color grading together. But so far very hard to do the same (white balance) using Color balance in Darktable.

I am just saying with new workflow I sometimes need more steps, maybe I just need more practice and experience.


Yeah. I found out you’ve gotta learn it and understand it. Nowadays most of my edits are “2-3 modules tops” with less fiddling than ever. Previously I spent up to 1h per photo achieving “acceptable” look, now I can crank them out (my record was 15 mins + export time for 130+ shots from some event. some though are way more challenging than others :wink: )

TBH there’s code to create those circles in color balance ui but it’s “not yet there”. @anon41087856 done phenomenal job with it and other modules. And for white balance - I’m working on a bit of white balance ui improvement myself :slight_smile:

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But white balance is a separate module and probably shouldn’t be done with the color grading, right?

White balance = fairly objective, technical correction

Color grading = subjective, artistic enhamcent