I am glad that we were able to clear up the misunderstanding.
I never questioned the quality of your explanation. I just realized that the way it works is too “high” for me and I understand so little about these numbers.
I just wanted to know how to apply log tone mapping. It was my mistake for asking how it works - there’s a big difference.
The video was very descriptive, but your text is hugely important to me because now I understand much better what the sliders do. This makes it much easier for me to see what they do in practice, I know what I have to pay attention to in order to see and understand the effect.
It has clarified a lot and now I have enough knowledge to practice and gain my own experience with it.
It’s not the lightest, it’s just the user selected value. The tool doesn’t clip anything, and brighter tones can still be compressed later (e.g. by a lut or by the new “base curve” options in the tone curve).
For me, “Target gray point” changes the mid tones the most, but also the dark tones and the black. Only the white remains untouched. Is that different for you?
It’s not different, it works the same here. But it does not change the black point for you either. In your screenshot, the black point is set to be 13.5 stops below mid gray (that’s what “-13.5 Ev” means in the GUI), but the darkest band in the test picture is only 10 stops below mid gray. If you set “black relative exposure” to -10, you will see that the darkest band will stay at zero no matter what value you set for “target gray point”.
Hello @jonathanBieler
I don’t know if this is the right way, maybe you want to know something completely different: But I manage to make all white levels visible with RT, just with “Dynamic Range Compression” > Amount > Maximum = 100.
I may be missing something but aside from reading the tools’ absolute values out of the sidecar (arp) we can’t tell anything without the raw file. We need both to really see what’s happening.
That said, a few points:
If at all possible try some kind of lens profiling, whether from LensFun (auto or manual) or from an LCP file.
Make sure you’re not double-correcting for CA. Both Profiled Lens Correction (Transform tab) and Chromatic Aberration Correction can potentially correct CA. But if they’re both enabled it can overcorrect. For my lenses, I’ve found the Raw CA tool works better than even the custom LCP profiles I made with the Adobe Lens Profile Creator. Who knows – Maybe I just did a poor job on the LCPs…
The Defringe tool (Detail tab) and correct for fringing beyond what CA tools can do, across the color spectrum. Just be careful to not introduce artifacts.
It’s theoretically possible to use the Local Adjustments Color/Tone Correction tool with a finely tuned Color Similarity mask to mitigate this but it would be a last resort for me.
@micha@jonathanBieler
I modified (a little) the code of “LA Log encoding” and “LA Cam16” (when Log encoding is activated in Pre-Ciecam).
From scope = 50, “ΔE scope threshold” and “ab-L balance (ΔE)” are modified internally, as well as the reduction of deltaE. Maximum effect since scope=90.
Hello @agriggio
I have worked through all the information on this page again and again.
I now understand a lot more.
Now I also see that you have given everything you need to know to understand Log Tone Mapping. You went to a lot of trouble and were very patient, even though it took me so long to understand the technical background.
Once again, my heartfelt thanks for your commitment - and of course for the great software.
In my personal opinion, any tool (and lessons on working with light, too) is well tested when working with photographs that contain people’s faces, people. All the flaws of any tool and lesson come to the surface. And houses, eagles, cats, mountains - all this is about nothing. When interfering with the tone curve with this tool, no matter how you look at it, the picture is killed, or something. It becomes unnatural. The tool is funny, but you need to handle it very carefully, so as not to be tempted by the result once again, which will then not only disappear when viewed again, but will push the viewer away.
Again, this is purely my personal opinion. It’s clear that I can push it into…))
These are very interesting thoughts that you express here. These thoughts are enormously important in what we are doing. And you can’t ask yourself often enough, what am I doing, why am I doing it and where do I want to go with what I’m doing?
Yes, the pivotal point is always the person and, above all, their face.
In evolutionary terms, it was extremely important for us to be able to correctly interpret the intentions of our counterparts. We are highly specialized in correctly assessing the intentions of other people.
And this is also evident in photography. Nothing is as exciting as images of people. And appearance plays a very important role in this. Also the brightness and, above all, the color of the skin on the face.
However, contrary to what I think you mean, I think I have understood that manipulating the tone curves is sometimes very conducive to creating a suitable image. The results out of the box from the camera are already interpretations and not reality itself.
And that brings us back to ART and why I like this software so much: The operation is extremely intuitive. The science and technology is well hidden under the surface. I can concentrate fully on what I’m looking at and when I’m experimenting with the relatively few sliders, I’m not distracted much. So I can concentrate on what’s really important.
And what is a saturation control one under all sliders? I turned this item on and off, but I still don’t understand what it affects. There is no difference in the image, ever. Is this some kind of experimental tool that hasn’t been fully developed yet?
And further. When we change any values anywhere with these tools, the saturation does not change. Do these tools work in L curve (lab)? Lightness seems to be detached from the saturation channel.
