Filmic - adjusting with Levels vs Exposure module

Greetings all, first-time poster here although I’ve already conversed with some of you on other forums

I’ve gone through the extensive tutorials and white papers on Filmic and Tone Equalizer and I think I have a pretty good understanding of their principles.

As I understand the workflow, I would adjust exposure for the mid tones prior to enabling Filmic but I found that I seem to get better and faster results if I adjust exposure with the levels module instead.

Can someone tell me if there’s any merit to that approach, or conversely, I’m working against the intent of the Filmic process?

Thanks
Dave G

I advise to set filmic middle grey to 18%, then use exposure to compensate globally the mid-tones, then come back to filmic to set up the white and black relative exposure.

Why ? Because it’s more fool-proof, because it anchors the full dynamic range mapping around mid-tones, which can safely be assumed to contain most of the important details in an image, and because it results in a better-balanced filmic curve (where black exposure ~= -white exposure) which is easier to control.

TL;DR : it makes a better-behaved and safer workflow.

But setting filmic middle-grey from 18% to 9% is exactly the same as adding +1EV in exposure. Except for the modules that come between exposure and filmic (because if you push exposure by 1EV, then your RGB values could go past 100%, which is not a problem for the pipeline, but the parametric masking GUI gives you control only in the [0;100] % range, so you can’t set up a key-framing between 50% and 120%, for example).

In future versions of filmic, the scene-middle grey might be hard-coded to 18.45% and disappear from the GUI, because it’s redundant with exposure, and on second (third ?) thought, it only duplicates features.

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is changing the exposure with the waveform (the tooltip says “drag to change exposure”) the same as doing so in the exposure module?

Yes, histogram and exposure are linked.

A feature which was discussed to be removed.

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That would be unfortunate. Why?

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Thanks, I think that answers my question.

FWIW, if you decide to hard code the middle grey to 18%, I hope that you’d also add an exposure slider within Filmic. It would be a lot easier than hoping over to a separate exposure module…

I have to agree that removing the Levels modules would be unfortunate. While they may be redundant, they are of great help to people like myself who are familiar with that format and new to DT. I dropping that tool will make it harder for new users to adjust to this program.

To clarify, I wasn’t talking about levels.

I was just observing from a UX efficiency standpoint it’s better, I think, to open filmic, set middle gray, and adjust the exposure from the histogram, rather than to switch to another module, and then back.

But … I’m new to DT also, so may be missing something.

Out of interest - regarding the Levels module - Dave OP queried whether it was against the intent of Filmic. I think using Levels must generally make the image data non-linear. But am I right?

Exactly… that’s why I asked

Dave G.

There is RGB levels which you should use to keep the adjustment linear.

Does it keep the adjustment linear? I’m not sure it can if it allows you to set black, white and mid-grey points. Perhaps if it just let you set two of those values, but not three (but then it would just be the exposure module).

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It’s working in linear RGB space.

Yes, but it’s a non-linear operation. It’s essentially equivalent to a curve with 3 nodes (black, white, grey)

Something like this:

Screenshot_2020-02-09_17-15-57

Though you could set the grey point such that it remains linear. Again, though, that’s just the same as the exposure module gives you.

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No, having one and only one place to set the exposure is better for a workflow. You can have filmic and exposure in your favorite modules, so you have both under your eyes anytime.

Now, you can already do that solely from keyboard shortcuts + scrolling. The problem is the “active histogram” is an hidden function, it works badly with touch events/screens and, more importantly, you never know how much exposure you add for the amount you dragged.

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RGB levels work in whatever RGB space, but surely de-linearize the signal if you use the grey point. The levels algo does:

RGB_{out} = \left(\dfrac{RGB_{in} + black}{white}\right)^{grey}

So you see that the white correction is a simple exposure compensation (same as the exposure module, or the slope in color balance), the black one is a simple offset (same as the offset in color balance or black level in exposure module), and the grey is the only non-linear part (same as the power/gamma in color balance, same as applying a curve with raised midtones).

In my opinion, levels are fully redundant, feature-wise, with other tools, but are also more limited since you can’t reduce contrast (you can’t set white to more than 100% because… the GUI is grounded into the display-referred workflow).

That’s also the true limit of knowing a soft only from its GUI. Deep inside, you might have 3 tools doing exactly the same operations, and be mislead into thinking they are different tools just because they have different UIs.

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It might be funny from UI perspective to merge modules doing exact same math on image and have module GUI mode switch.

This does bring up a follow-on question. This advice seems to depart from the guidance that I’ve seen from the write-up and video tutorials (including your excellent 3+ hours on Filmic and Tone Equalizer), where the recommendation is to first set exposure and then adjust the mid-grey slider. Would setting Filmic middle grey to 18% followed by exposure compensation give me a different result than adjusting the middle grey slider alone (that assumes the original exposure is already satisfactory)? Just trying to understand the best way to use these tools… thanks in advance.

I’m not completely sure I agree with that. I understand the argument of having one control in one and only one place. But in the same light I would think a better workflow for a module is to have all the necessary controls for a module within that module - even if it does cause some redundancy elsewhere. However, your suggestion of placing the exposure and Filmic module in close proximity within favorites is a pretty good work-around

I would only argue for keeping levels, while redundant and possibly limited compared to other modules, because its a standard tool that most reasonably experienced users recognize and use and is therefore helpful for newcomers to transition to DT.

There is no point in setting both exposure AND scene mid-grey, they do exactly the same thing. It’s either on or the other. I mean, you can set up both, but that will only add one step, and no benefit.

As I said, set filmic grey to 9% or set filmic grey to 18% AND add +1 EV in exposure, you will get the exact same result. The difference is, in the former, your filmic S curve will be de-centered so adjusting its shape might be more wonky.

But that’s just a matter of ordering the UI so both controls are close from each other. Duplicating features is only a less straightforward way of doing it.

I would just love if users focused more on what the tool does, rather than on how the tool looks. Because the critics we hear most of the time is darktable having 5 different ways to do the same exact thing, and then people get confused because, in their head, there is an exact 1:1 correspondence between UI widget and image processing filters, so 2 different widgets should perform 2 different operations, and they try using them all while they only undo in one what the did in the previous.

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That’s fine saying that, but for someone that’s trying to get to grips with how darktable works, I’m not even sure what you mean there. I for one don’t care how a module looks, I only care about how any of it works, and what it does.

Having so many modules duplicating functionality, but often with different names, or even a completely different interface. It’s not wonder that it’s confusing for newcomers.

I agree though, that when I read this article, it was only apparent to me that this was opposite to any information I’d read up to now.

For a user coming from other software, that is used to working a different way, none of this is as obvious as it is to those that are programming it.

The more I’m studying this forum, and other articles, the less clear it’s becomiong as to a sensible workflow.

I did get some reasonable results editing my newer Nikon images, but have so far completely failed to get anything usable from my older Olympus images.

I appreciate that darktable has some fantastic editing tools, and has the potential to produce some of the best images possible. But, there appears to be absolutely no consistancy in how I go about it.

For now I have abandoned darktable, and removed it from my system, but I still monitor progress, and this forum, for any revelations that might make it work for me.

It’s clear that a lot of work goes into darktable, but IMHO it fails miserably with regard to UI and workflow. I’m not one for pretty interfaces, but they do need to be reasonably well laid out so that a normal human being can understand what is going on, and how stuff should be used.

Sorry of that comes across as a bit of a rant, it probably is one, but I am finding some of the comments here are very much looking down on the poor peasants that never got an education.