Recently I have started to exclusively use a scene referred workflow in Darktable. Hence, I stopped using the tone curve and started to use only the tone equalizer to change the tone of my pictures (because the tone equalizer is scene referred while the tone curve is display referred).
However, I feel quite limited when using the tone equalizer by its low number of bands, I would like to more precisely adjust the contrast on certain areas of the histogram. Is it possible to increase the number of bands of the tone equalizer, or keep using the default number of bands (8) but on a narrower part of the histogram?
I’ll dig it up but there are one or two very extensive threads on this and why the module works as it does…I will edit this later when I have time to look or you can search…
I will just add that you should be careful when restricting the tone equalizer to a narrow range. When you do that, it can have some weird artifacts, and EIGF for “preserve details” doesn’t always give good results, so experiment with some of the other ones like guided filter or even “off”, which is more like a traditional tone curve.
The tone equalizer is primarily designed to do things that DECREASE contrast (raise shadows, lower highlights) without too many negative side effects on local contrast. It is a better, more precise and scene-referred version of the shadows & highlights module.
If you want to use a tone curve for increasing contrast (“s curve”), you may prefer the RGB curve module.
If you really want to use TE for this, turn off the guided filter, as it will work against you. However turning off the filter will make you loose the contrast compensation control (this might change in my next version).
I will admit that even after fine-tuning the tone equalizer, I still prefer the tone curve-style with unlimited numbers of points. Seems more intuitive to me. But I try to use the tone equalizer whenever I can. However, for doing something like a local adjustment (brightening catchlights/darkening bright spots), using the tone curve is just plain easier even if the tone equalizer can accomplish the same thing.
The Tone EQ is a spacial adjustment, it changes the brightness of areas, but leaves the relationships between pixels in the area alone.
The Tone Curve is a tonal adjustment, it changes the brightness of all pixels equally, with no regards to their neighborhood.
As such, I use the tone EQ for brightening a foreground, or darkening the sky – that’s thinking about areas. The Tone Curve (or more likely Color Balance) I use for raising the black point, or increasing brightness – those are pixel changes.
While I do tend to think about the modules like this, I do have a generic “brighten shadows” preset that uses the tone EQ indiscriminately over a very broad tonal range. This doesn’t fit the metaphor, but it just works very well .
One would think that points 0-8 would be more precise than the four brilliance sliders of Colour Balance RGB — but, for most of my pictures, I find that they are enough. And even when I have used TE, I’m likely to adjust CBRGB as well.
I’d find it hard to use without the “simple” tab. There is some curve maths that is the god of TE. It can be very hard to adjust the relationship between two adjacent points on the curve tab. One is soon riding a bumpy road!
Yes, I’d probably prefer a point free curve. But it can probably be filed with the old joke in reply to asking directions to some place: “If I wanted to go there, I wouldn’t start here!”
It is a very useful tool. In the hands of experts (watch Boris’s videos), it is a grand-master tool.
It is also evolving. Who know… one day we might have a Tone Parametric Equaliser!
I agree with this because I also like to be able to add my own points to a curve for maximum control. Previous discussions have talked about adding more control to Tone Equalizer or adding Tone EQ’s guided filter to RGB Curves to get the best of both worlds. I’m looking forward to trying out @JovianSettler’s Tone EQ redesign…
For now, I mainly use Tone Equalizer for broader changes rather than fine contrast work. I now rarely use it without the EIGF because the simple tone curve doesn’t offer enough control.
It’s best used to decrease contrast and preserve details, although I’ve found that the EIGF can give a nice soft contrast effect if you keep it activated and ADD contrast. Used judiciously, it can produce a soft diffusion and glow that can look quite appealing.
Yes it is, but I’m not sure this was made clear when the module was first created. The module’s author called it a “dodging and burning” module, and the manual still says this about it:
“this module replaces the need for other tone-mapping modules such as the base curve, shadows and highlights, tone curve and zone system (deprecated) modules”
I think there’s a suggestion there that you can replicate the functionality of those other modules, but in reality it’s quite different.
I’ve made my peace with it over the years, but I was initially frustrated that I couldn’t easily control the 8 zones that the nodes create, which you could do with the old Zone System module (albeit with display-referred issues). I’d say you can only control about 3-4 zones max with ToneEQ, and it works best on just 1 or 2 zones.
Oh yes… confusion of terminology. I was jokingly referring to the kind of parametric equaliser found in audio, where, for each point, one can change not only the frequency and the value, but the slope of the curve and the breadth of effect.
It was a throw-away line. Sorry for the confusion.
Yes absolutely! I feel the same way. And a guided filter (not EIGF but maybe average) would be cool in a tone tool. The only thing is, which I think can be confusing to some, is that both the Tone Curve and RGB curve are display-referred, and are somewhat discouraged by various entities… but IMO they still are necessary.
And I don’t really agree (with the manual) that tone curves make no sense in a scene-referred workflow just because there is no strict definition of zero or 1. In my mind, it doesn’t really matter as long as they are defined over some tonal range. The fact that they appear to be limited to 0 or 1 in their graphical representation doesn’t mean that they aren’t intuitive from an artistic sense even if they appear to have hard 0/1 points.
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