Principled processing workflow in DT 3.2.1 (Filmic)

Processing
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Hi all,

IMHO, something that is still missing in Darktable and is hindering a more widespread use is a concise, clear guide to a principled approach to basic raw development. I have watched quite a few video from Bruce Williams and Aurelien Pierre, but I still feel I don’t quite have a sure footing about how to proceed in general. I understand that in DT you can do similar things in many different ways, but that is not too helpful unless you understand in depth all the details of the different procedures (and their combination).

Aurelien did publish a quick guide that addresses this aspect a while ago, but it is written for a previous version of filmic. Would it be possible to update it for the new version?

Perhaps I should clarify better my point by illustrating where in the workflow I get a bit stumped:

  1. import an image into DT using the new scene-referred workflow (ok, here!)

  2. use the Exposure module to adjust the overall exposure…. but according to which criteria? I can think about at least two alternatives here:

    a) move the exposure slider so that the average image exposure looks right. I understand that the default values are conceived for average exposures using matrix metering in the camera, but if one uses manual exposure (eg, for ETTR), the defaults won’t work well. So, for example, if I have exposed the picture taking care not to blow highlights, by raising the exposure slider in this module to a reasonable middle grey value, the highlights are going to clip now.

b) move the exposure slider taking care not to clip highlights (toggling on overexposure indication): I think, though, that Aurelien advised against this, saying that highlight management will be done later on in the Filmic module.

And what about Black Level Correction? Should I adjust that so to avoid clipping or should I pick a value that just “looks good” for the image?

The problem with this is that, whichever one of the above strategies I use — even when the image has no clipped highlights or blacks in raw — I find it quite difficult to adjust the parameters in Filmic to get an image with nice contrast and no clipped highlights or blacks. (I have to say that I go back and forth moving sliders by trial and error, and hence my plea for a principled approach).

Now, if the purpose of Filmic is simply to do a nice, natural tone mapping, why couldn’t Exposure simply set the black and white point automatically according do the image data (min and max intensity values) and then use Filmic to add contrast without clipping extremes? Indeed, shouldn’t a curve like Filmic’s, which is anchored to the max and min point, never produce clipped values barring floating point precision limits (i.e., it should go asymptotically towards the clipping values)? What I see instead, that as I adjust contrast (or other sliders in Filmic) in order to regain some contrast, it is very easy to clip both highlights and blacks.

And while we’re at it, a final question… (sorry for the lengthy post :-). If there are indeed highlights that are really clipped in the image (= clipped in raw), couldn’t the Reconstruction part of Filmic automatically set a mask for those pixels? That would be another step towards simplification.

I don’t mean at all to criticise Aurelien and the all the others DT developers who are doing an outstanding job, for which I am deeply grateful. I just feel that some clarification in the sense described above would greatly help in increasing the adoption of DT. I myself am using Lightroom (last standalone version) as my main software, and would really like to switch to DT as I can see its better potential, but as of today I am still unable to match LR results in a reasonable amount of time. BTW, if somebody was willing to write such a principled guide to DT workflow, I, for one, would be happy to buy it.

Thanks
Giuseppe

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Simplest processing: activate scene referred workflow in presets - so the required modules are already activated.
Then adjust exposure until the midtones are ok. Since filmic is activated it will take care of the hightlights.
The you can adjust the sliders on the look tab to increase contrast.

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If there‘re clipped highligts, you can use the settings on reconstruction tab to mitigate the effect (maybe also set highlight reconstruction module to „reconstruct in lch“)
Colorbalance is the last step to tweak for a simple basic editing.

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I think, method a) is correct. Trying to avoid blowing the highlights while taking the shot is crucial. “Overexposing” while setting the exposure module is okay and can be corrected later.

With regard to black level, I try to set this in filmic or even later in other modules and not via exposure module.

Because this may not look like the original scene. Personally, I also like to do my own interpretation and will not go for just “nice”.

Concerning clipped highlights and automatic correction: There might be possibilities but it is certainly not enough to mask overexposed pixels. The mask has to fade out and for this you need some choice.

The automatic “nice” exposure is in general done be the camera software for the JPEGS. If one develops RAW there should be more choices.

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Ive only explored filmic for test purposes so take that into account.

  • forget highlights when using the exposure module
  • shadows and black clipping are really hard to control with filmic. It is more focused on midtones and highlights. You are better off using other modules to handle shadows.
  • apparently (people who actually know might correct me) its impossible/hard to auto detect correct blacklevels due to noise or somrthingy.
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To me it sounds a bit like you are maybe in the trap of looking for the magic “correct” solution with filmic, ie the “right” settings. This is so common with many of the darktable modules. I think you use the histogram as a guide and your eyes and use the tools to come to point where “you” like the look of the image…there is no magic auto setting for something like filmic at least that is my understanding of how to use it…also I think if anything filmic desaturates highlights and shadows so it often appears to remove contrast in some image. I believe AP clearly states this on numerous occasions as the intent of filmic and suggests the use of local contrast, color balance an contrast equalizer to provide saturation and contrast back to the image…so certainly you can play with white points, black points, and contrast in filmic…I think its real role is a nicely tone mapped image not a contrasted near final product…that has always been my take on the use of filmic…if you look at video editors using log to cram everything in to the dynamic range they are such a flat looking things at the start but all the information is there and its easier to add back contrast etc to a balanced image…Just post an image on the playraw forum at pixls.us and see how widely it will very…each person thinking they have a good edit and they do …to their eyes it is a good edit…it can be a trap to take a module with an expectation that plugging in a set of numbers will have it produce the look…with raw images your eyes are the best tool and you massage the look with the modules but you can create it with them…

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Way back in the early days of filmic it was suggested to temp turn on raw de-noise with a high strength and then use the picker to set the black level and then turn it back off and proceed with the edit…this was as you say I believe to deal with noise in the shadows affecting an accurate black level

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Lots of jpgs look great but check out the histograms …often stretched with some clipping at both ends…

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This is how I work with Exposure and Filmic. Make sure the linear workflow is enabled by default. Also realize that the default of +0.5 is supposed to be a general starting point. If your exposure is consistent in general, you should tweak this value using a preset so that the value is closer to how you like it.

  1. Open the image
  2. Adjust the Exposure module until the midtones look good. Pay no attention to clipping highlights or shadows. Exposure is for the mid tones
  3. In Filmic, adjust the highlights until they don’t clip
  4. In filmic, adjust the shadow until they don’t clip.
  5. Fine tune highlights and shadows in Filmic until I’m happy.

Now that I get the hang of it, this process takes 30 seconds to a minute.

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I find that I enable the grey slider again from options instead of going back to exposure or trying to guess how much to add. The default settings work pretty well for me and I just tweak the color preservation model starting from none until the color looks right and then adjust with the grey slider rather then mess further with exposure…above I think there was a comment about filmic being anchored at the ends and I think that is not really correct it is more anchored by the middle grey/exposure and then you map to a range of EV on either side that you set…if your image has extreme dark or highlights then you are going to need more ev in the range. I do like the new way to handle the midtones…I find it very intuitive to set the range based on the latitude and then to add or subtract saturation with the new mid-tone slider. All in all it works pretty well most often

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@gpagnon: that’s my problem, too. I’ve played with filmic and basecurve and, filmic looks much more naturally than basecurve. JOF’s even don’t look naturally. Now, I’ve really (I see it) understand what AP means.
But, I guess, I want to have a module group or a list which modules are safe to use. There is a (outdated) list and there is information about this at several places. F. e. I find “local contrast” bad in most cases, although it is recommended.

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I used to do it this way, but although filmic white relative exposure slider can prevent clipping, it doesn’t bring back detail lost through clipping exposure. So now my process is to boost exposure only to the point there is no clipping, or that the details clipped are of no great loss, and adjust overall brightness using middle grey luminance slider in filmic (which needs to be enabled firstly in the options tab).

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My understanding is that the middle gray slider in Filmic RGB and the Exposure module do exactly the same thing. So the white slider can bring back detail that has been pushed past the histogram’s edge by the exposure module. I just tried to blow out the mid tones of a file using exposure and thing bring them back with Filmic RGB’s white slider; it doesn’t look good, but it works

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Why use exposure and not basic adjustments? I like the auto feature in basic adjustments for a ultra quick starting point, and as a bonus I get contrast, saturation and vibrance.

Generally I think a quick start guide would be helpful to people new to darktable. I often read that people get it, play with it a little, delete it.

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This article tells you which modules are recommended and why and is not outdated: PIXLS.US - Darktable 3:RGB or Lab? Which Modules? Help!.

You can still use all of the modules but some must be used with care (don’t push the sliders too far) and, as with anything in darktable, there is usually more than one way to do something, so prefer the methods recommended in this article.

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That is my understanding too, I may have been incorrect in saying “it doesn’t bring back detail lost through clipping exposure”, but I have certainly seen detail lost that couldn’t be recovered - it’s why I changed my workflow. Perhaps there was another module used in between exposure and filmic which clipped values irretrievably. So the main difference is that middle gray adjustment occurs late in the pipe, whereas exposure occurs early. Perhaps if you boost exposure beyond 255, and don’t use any modules in between it and filmic that irretrievably clip the data, then your process will be good. But if you push values beyond 255 then clip them in another module, they are lost to filmic. So how do you know which modules clip irretrievably and which don’t? I’m quite sure the current channel mixer does (but the new one in the works won’t). Not sure about the other modules.

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Hi,

thanks for the reply. This is exactly what I do, but getting good results is not quite easy and requires a lot of going back and forth.

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Hi,

thanks, I agree with your comment that mapping the black and white level to the min/max will change considerably the image look for some pictures, but I thought you could then refine the tone mapping via the Filmic module.

As for the automatic masking of the clipped-in-raw areas, for the purpose of highlight reconstruction, isn’t the degree of fading out of the mask already controllable by the Transition slider?

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Thank you, it does make sense.

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Thank you. When you say “In Filmic, adjust highlights and shadows”, do you mean the White Relative Exposure and the Black Relative Exposure sliders in the “scene” tab? And do you not touch the Look > Contrast slider at all?