Two ways of using Filmic RGB

As Aurélien teached us, there are two ways of using Filmic:

  • Expose to the right, without clipping highlights, and use Filmic RGB to “recover shadows” (apologies for the legacy terms)
  • Expose for the subject, do not care about overexposure, use Filmic RGB to recover highlights
    See here below a picture of a typical “HDR” scene, where part of the frame is in direct sunlight and the other part is in shade.

DSC06629.ARW
This file is licensed Creative Commons, By-Attribution, Share-Alike.

Here are my results applying the two methods:

DSC06629.ARW.xmp (6.8 KB)
DSC06629_02.ARW.xmp (6.8 KB)

It seems to me that with the first method you get better contrast in highlights, but shadows suffer a bit, there seems to be more noise, while with the second method you get cleaner shadows, at the price of more compression in highlights.

Thoughts ?

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The raw file didn’t upload properly. Edit It is okay now. Thanks!

I haven’t used the new filmic or enough of the old one but I don’t think it is an either-or. As long as the histogram doesn’t peak in the shadows or highlights prior to applying filmic, you should be fine. If you are stuck, from his recent post, it may be because you are selecting a DR preset too narrowly.

I really like the second version! But your blacks are terribly crushed in the first version…

Yes, this is the point. If you care about what is in the shadows, the second method seems preferrable.

In your edit you somehow have local contrast before filmic rgb. I don’t think that’s correct.

Here’s my edit that only uses filmic rgb and nothing else. I could probably have gotten a little more oomph out of it in terms of saturation, but getting a good start is quite easy with filmic!

DSC06629.ARW.xmp (6.8 KB)

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I think that’s the order it was in for darktable 2.6. If the photo was imported in 2.6 and then processed in 3.0, it will retain the original module order. Discarding the history will reset the order.

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Oooops! You are absolutely right, I don’t know what happened, maybe I was starting from an old edit. Must be more careful with order of modules.
With the correct order the results of the two techniques are actually very similar.

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Since there is no single dominant subject in the picture chosen for demonstration, obviously the first method is preferable. The second method of not caring about highlights works best when you have a strong single point of interest in the frame.

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Aren’t they the same thing? I think the middle gray luminance slider is the equivalent of exposure but with a different name

middle gray luminance = 18 => exposure module = +0 ev
middle gray luminance = 9 => exposure module= +1 ev
middle gray luminance = 4.5 => exposure module= +2 ev

No. Yes. Well…

I’ve come to dislike the term ‘exposure’ in post-processing terms. In @MarcoNex’s first post of the thread I looked forward to poring over two raw files in terms of their different “exposure”, but was dismayed to subsequently find out we’re discussing at a filmic slider or dt’s “exposure” tool.

“Middle Gray Luminance” seems to me to be a more appropriate term, notionally…

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In post-processing, “exposure” means nothing. No post-processing can change the exposure. Exposure is fixed when the camera took the photograph.

Worse, labeling something “exposure” in PP is misleading. The actual exposure by the camera determines what data we have, and what we have lost due to highlight clipping or noise in the shadows. No amount of tweaking something called “exposure” in PP can get that data back.

There is some use for “zones” as described by Ansel Adams. But these are not “exposure stops” after the camera has exposed the film. And digital has so much more flexibility than photochemical emulsions that we shouldn’t get stuck in old paradigms.

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Well, maybe…

Let’s remember there is a reference to Ansel Adam’s zone system, and there is that word “film” not-exactly-hiding in the title. What do you do with film negatives? You print them. What do you do with over-exposed negatives? You change the exposure of the print to compensate. Admittedly, you increase the exposure of the print to compensate an over-exposed negative, but never mind.

In fact filmic is very “enlarger oriented”… you map the mid-grey (select exposure time) and you change the slope (select paper contrast).

Still, exposure really means “pretend like you could go back and change it”. It gets the idea across.

Thing is, dealing with the two in the separate situations has different implications. Increasing exposure at capture can push highlights into sensor saturation, where the data piles up at the saturation point. Increasing exposure in post, with a floating point data representation, lets the highlights grow past the value where one wants to call “white”, preserving the opportunity to use that data to reconstruct some kind of definition below “white”. For shadows, increasing exposure at capture moves the light measurements out of the noise floor; increasing exposure in post just moves the noise…

When I read @MarcoNex’s post I was initially considering the former, when he was really talking about the latter. Graham, I know you get the difference, but overloading the term here opens the door to confusion…

About the term “exposure”, I thought in the context of post it could be short for “exposure correction”. That would at least not pretend to change exposure but its result … Sorry, just my 2c.

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Confession: I call it “Exposure Compensation” in rawproc… :smile:

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How about “xxx Intensity”? Luminance is otherwise well defined.

I’ve struggled with finding a semantically-appropriate term without using more than three words for this. In my hack software, I still call it “Exposure Compensation”, which almost takes the whole width of the toolchain pane. If “stops” weren’t involved, I’d be calling it “Multiplication”, which is fundamentally what the operator does…

if you don’t like exposure compensation, why not gain?

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!!!

Sometimes the best answer is so simple… Thanks!

I think I’ll make ‘gain’ an alias for ‘exposure’ in rawproc, soes I don’t disturb anyone’s prior processing, if there are ‘anyone’ else using…

Because this is the thongue of the dark side … pro video people … ugh! :crazy_face: