Sigmoid module advice and guidance needed

I am really pleased that the new Sigmoid module has appeared in the weekly windows build. Now my questions are about understanding its purpose and strengths. Which modules is it designed to complement or replace? Is it meant to work with Filmic? How do I best get started with using and exploring the new module? Thanks in advance for your help and advice.

Display transform option for filmic… has different chroma preservation and no gamut check…

Summarized in detail here…

Hi Terry,
I expect I might be doubling up to Todd’s reply… but briefly, it’s intended to be used instead of filmic, doing more or less the same job.

I have all of my most used modules on the quick access pane in darkroom, and I’ve added the sigmoid on/off and contrast slider to it so I can easily switch off filmic and turn sigmoid on to see which works better.

So far I often like the colours and contrast that sigmoid gives, but find I need to make use of the tone equalizer more often to bring highlights down and shadows up.
But, that might be due to me overusing the contrast slider in sigmoid!

The two different modes in sigmoid are quite different - I haven’t used the rgb ratio much as it seems to give results quite similar to filmic, whereas the per channel option gives more saturation, to the point where on some images one doesn’t need to add much at all in color balance rgb.

This is all just my thoughts at present… I’m very much only trying things out!

You can also abuse the skew and get a lot of help. I have maxed it out on a lot of images and I am stull happy with the bump in detail and contrast that is needed

Yes, I haven’t quite got a feel for that slider yet. On many images so far I don’t like the tonality if I lower it (slide left) but things usually look good with it increased (right) if the highlights don’t ‘blow out’. I know they don’t literally clip, but they can become compressed to the extent that it looks clipped. But tone eq can sort it if needed!

do you have filmic activated or deactivated when using sigmoid?

For me, filmic deactivated. I saw a post in the main sigmoid thread explaining that using both at once has unintended results. I tried using both - not good! That was only on one or two images but it’s certainly not the intended use, as far as I know.

They are both expecting scene data not display so using both makes little sense…

Yes. Here’s the post I was thinking of: Evaluate the new sigmoid tone mapper just merged into master ... - #85 by jandren
Near the end of the post @jandren says the same thing…

Haven’t tried to use it, but looking at that GitHub explanation, I’ve no idea what it’s trying to do. With filmic, after reading some stuff and watching a video or two, I can understand the concepts behind it and what any changes are used for, even if that’s just a gross simplification of the activity under the hood. That’s what sets DT apart for me, rather than the ‘waggle the sliders randomly until it looks ok’ approach of other soft. Hopefully someone will explain at some point what the aim of this function is (that doesn’t involve wading eyeball-deep in a squillion post thread). Thanks

Basically the same thing as filmic using different math…its a based on a log - logistic curve so not the same space as filmic…

As for use pretty simple contrast slider… pretty self explanatory and skew… slides the point for the peak contrast and then a couple of hue preservation modes… no gamut mapping I don’t believe and of course no filmic highlight recovery tool either…

So the math of the curve is handling the global tone mapping and you can tweak contrast and where that peaks with the skew… and then address color shifts as you like…

Simple thing is to just try it on a few images and if you prefer one over the other just use it…

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Thanks Todd. I will obviously give it a go when I get chance. I guess filmic is more intuitive theoretically because its interface is like a souped up tone curve that most ordinaries understand. That quote you used above kind of makes my point. (I have no clue). It’s a knife edge giving a certain amount of control and comprehension to people so they don’t feel like they’re a dimwit who needs their shoelaces tying on the one hand or in need of a phd on the other

It’s early days, obviously, but it seems this is going into DT at some point, right? I guess there’ll be a need to get across to relatively avg users what they’re waggling with those sliders at some point, in the same way different people managed to do with filmic.

Really Tony its not that hard and there was a massive 700 plus thread documenting the evolution with lots of test images and comparision…even this thread already has many so its not going to be that challenging…use the first two sliders to manage your tone and then slide the chroma preservation to your liking…rgb ratio is more like a filmic method of hue preservation so you will see the salmon colors at times other times it can be nice… Thats really it…set your exposure and then tweak sigmoid module…and really often IMO so far not much waggling needed…

Edit sorry not this thread but the one I started for evaluation of Sigmoid …

I think I already mentioned the 700 post thread as a negative. My point is not that it will be difficult to use, I’m making the case that at some point it would be useful for people not into reading 700 unstructured posts what it’s all about in terms somewhere between teaching your grandma to code and teaching her to suck eggs (excuse the sexist, ageist metaphor). Trying to be helpful. Thanks

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I often use the dehaze preset of D&S…this is plenty sharp and contrasted for me so much so often I even need to pull it back a little so I don’t work too hard initially to really bump contrast/detail until I see what that does first…

There will be documentation as there is for all items and for sure the release blog post will have an entry. Technically it has just been merged so it is in testing. You can fairly rapidly scroll the 700 post thread and see where the image clusters and descriptions are…Filmic has been a very difficult module to get people to grasp and it has evolved and matured. I suspect that there will be some progression in the same way with Sigmoid but its simple and not trying to do too many things so I think it will be a much easier sell… I think in the link I provided above there are selected links provided to target most questions so if its not enough to learn it via self discovery there are definitely already some pointers to some basic information…

Great. Thanks

It really is all summarized pretty nicely here just incase you didn’t peek at it…

I did…

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