Do you know if darktable has a lightness control tool?

(Mica) #65

To be quite honest, using Harry Durgin’s video to prove that editing in darktable is slow is very disrespectful and disingenuous. He’s making a video to teach people how to edit, he talks through his decision making, often pauses to explain things, and shows the viewer the effects of a filter he is working with. Because he is making an educational video, it is at a slower pace.

(Roger) #66

No, I am making an factual comparison, because making the same with the Ligh EQ without explanation takes 10 seconds instead of 40 (WITHOUT USING THE AUTO BUTTON). I tested it by myself in case a comment liker yours would come.
I also verify if the video uses a common method and at least in YouTube, most people do the thing the same way, no matter what tool they use (Even ACDSee suggests such method to promote its Editor).
The method is time consuming by itself, no matter what SW you use, specially because you get new results with every adjustment instead of watching them all together.
How long may you take? Give a chance to Light EQ in mode STANDARD (including learning curve) to note the difference by yourself.

(Mica) #67

@R_O I think you missed the most important part of my last post:

I’d say two of those three things would be bare minimum to getting this discussion back on track, otherwise I think you’ve lost everyone’s attention somewhere in the paradigm void.


There have been a few points I’d like to answer to, but since they are scattered all over the thread I’ll just have a single post.

  1. darktable, RT and all the other tools don’t use a gamma curve for exposure, they use the correct and trivially simple approach of multiplication. Of course that brightens the shadows, too, but that’s the very definition of exposure. So complaining that changing the exposure of an image doesn’t increase the contrast in the image in just silly.
  2. The proposed feature is supposed to be able to add new shadows on objects. For that to work a simple approach that takes the existing brightness in the image isn’t enough, thus it’s not a tone mapping operator. Instead you need a depth map of the scene, which regular cameras don’t give you. An exception being systems with more than one camera (stereo cameras or more) and lightfield cameras, and even for those the results are not working great in many cases.

(Mica) #70

More or less, yeah. Divide the image into N luminosity sections. I guess the interesting part is that it gives you both highlights and shadows, so you can increase contrast in a particular zone.

(Gustavo Adolfo) #71

@paperdigits So the point is how they define those zones. In conventional luminosity masks, a shadows slider applied to a pure highlights band would have no effect at all, correct?

(Mica) #72

I’ve never used ACDC, so I don’t exactly know, but I’d guess the shadows are relative to dynamic range of the luminosity mask, so the tool on some clouds would darken the darkest part of the luminosity band.

(Christian Kanzian) #73

The Look of this example reminds me on the Old Oak - A Tutorial

You can so the same in dt with two instances of the tone curve with different modes.
Here is an Image where tried to copy that Look

(Christian Kanzian) #74

I watched this video

But what is the difference between a tone curve in dt divided in 10 to 20 points compared to this light eq?

(Gustavo Adolfo) #75

@pk5dark Do you mean scale chroma automatic in XYZ for the first curve and automatic in RGB for the second?

I did this a saw some results:


EDIT: But… what does it mean doing that?

(Christian Kanzian) #76


IRC one curve with L only in manuel mode and the second with automatic mode.

Tone curves looks like that for the example posted above.



If I understand correctly, these two curves give you ability to control the amount of desaturation in shadows (automatic scale chroma decreases saturation in the shadows). If so, you can use just a single instance of tone curve with its scale chroma set to “automatic” and blending mode set to “color adjustment”. Then you can control the amount of the desaturation with the blending slider.

(Gustavo Adolfo) #78

I couldn’t get good results with that, not sure if I’m missing something. If you could provide the raw and sidecar file it would be great.
As for my results, look for Tone Curve and Tone Curve1. Turn them off, then on. It really makes the image pop up, similar to LightEq results. But, like I said before, I’m doing this blindly, I don’t know what I’m doing with that.

CRW_2887.DNG (19.4 MB)
CRW_2887.DNG.xmp (18.5 KB)
(licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License 2)

(Christian Kanzian) #79

Your are boosting the contrast by this S-shaped curve.
The midtones are stretched over a wider range in the histogram. By pulling down the curve on the left side dark tones getting darker (left hill in the histogram after). On the right side light tones are pushed a little bit to get lighter (right hill in the histogram).


There is a nice thread here about histograms and tone curves were you can find much better explanations what is going on:

You can set the blend mode to difference to see what parts of the image are effected by the module and the changes.

Watching the last video I noticed the halos this tool could create. It looks like what shadows and highlights module in dt produces if pushed too far with the Gauß filter. So I guess there is some bluring filter around the tonal range controlled by the sliders to avoid harsh tonal breaks. Sorry, for this silly describtion, but I have no idea about the correct terms.

(Gustavo Adolfo) #80

I’m ok with S curves resulting in higher contrast. What I meant was that I don’t understand the meaning of tweaking the scale chroma for the L dimension on RGB and XYZ like I blindly did. But that it gave interesting results, similar to LEq, that is for sure (at least for this photo)

good tip, thanks.

I’m more illiterate in this terminology than you, that’s for sure, but your description didn’t sound different from what I’ve seen so far.

(Eduardo Battaglia) #81

Maybe a stack of “fill light” modules could work like op wants… although there are more controlled ways to work on an image like everyone here just explained

(Aurélien Pierre) #82

You might want to see that : A tone equalizer in darktable ?

Is that what you asked ?

(Roger) #83

Amazing job!
I could not see it until now because somehow pixels emails ended in the spam box.
It is amazing how you manage the dynamic range avoiding the mess that the ‘old’ multiplication method produce.
As you may see, my suggestion was not intended to copy cat ACDSee but to implement the exposure control of the modern mirror less cameras. The ultimate goal is SW in computers to work with the same scope than the SW in those cameras, gaining the advantage to modify the shadow levels in a per levels/zones basis.
You are a genius to achieve such results in 4 moths with no previous C knowledge and can not wait to try your module in Darktable.

(Pascal Obry) #84

@R_O: you can wait? You’re lucky I’m hardly sane since I’ve seen that and waiting eagerly for the final version :slight_smile:

(Roger) #85

Fixed :stuck_out_tongue: