That is a perfectly fine use case, and a lot can be done with that module.
However, this application is not what most people would call “local contrast”, which is an algorithm family amplifying the deviations from a local average.
The two would give different results when a relatively narrow area dominated by midtones is surrounded by dark or bright pixels. A cb-rgb instance masked to the midtones would introduce contrast there, while a local contrast (either its proper module or via D&S) would add additional contrast in the highlights and shadows, too.
In addition to Boris and Nicolas , Gus has some nice videos with a technical slant on some DT topics and related theory, and the the Darktable landscapes channel is pretty good … Also in tutorial form Avid Andrew has some articles…
And the manual is also a good source for many basic topics and module details…
Even then I think some of the best results are likely to have little to do with techinical editing unless maybe you are doing reproductions. If I even knew what a technically sound or rules based edit would look like I am certain it would look nothing like these images which I just love. Arek had his camera stolen and bought a second hand Olympus 16MB sensor camera and until not that long ago was using DT 3.01. I know he did upgrade some time ago now and he may have gotten a newer camera but many of these images came from that older kit and software without using the newer more “technical” modules/workflow…
I am sure his photos have gamut clipping and other technical deviations but that is the last thing I think about when I seem them. I love his color and compositon and I just love the way the photo’s look… I’m pretty sure he doesn’t bother too much or edit to the histogram or gamut clipping warning and has a vision when he edits and drives the photo to that…
Yes, me too. The fulcrum feature is really useful. The only slight annoyance I have with it is that you very soon introduce clipping in either the blacks or whites, so it’s best used with a parametric mask to protect the extremes.
I feel its functionality could be even more useful if you could also pick your black and white points, similar to how RGB Levels works. That way, you can restrict its effect from the start without needing parametric masks.
Actually, you can (and I think should) pick a white level in color balance rgb, but it is not used with the contrast calculation (which changes the brightness relative to the selected fulcrum using a power function, where the selected contrast value is the exponent).
Yes, you’re right, but that white point picker is for the Power function as you mentioned. I was referring specifically to the contrast slider. I like the idea of a picking your extremes as well as the fulcrum for contrast adjustments.