Filmic RGB vs in-camera Exposure Compensation

darktable is a raw software. It needs to care about raw workflow.

Creativity comes in your camera through the pictures controls (brightness, contrast, saturation, sharpness etc.), that drive the raw → JPEG internal conversion. What you may want to do is dial down the brightness in there. Exposure has nothing to do with the final look.

Again… I do believe that filmic needs to take into account whatever params are set in exposure module. However, I’m against duplicating the exposure bias setting in filmic. What needs to be done is to allow a pipeline “metadata” in darktable that lets critical modules share info, such that filmic can adjust its default to whatever is set in exposure.

That was already discussed with Parafin and @houz on IRC last week, so far, clean ways to do so are still to find. I don’t want to hack the pipeline (I barely understand it) in a hasty way.

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That is good to hear! And lest there be a misunderstanding, I am absolutely grateful for the work you and others are doing, and am in no way angry or bitter about your responses and comments. After all, Filmic does produce fantastic results, even for my non-standard workflow.

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Yes, well, my Fuji doesn’t have a brightness control (right?), so I have to make do with what I have instead, and that is the workflow I described. There are three DR modes that lower exposure but compensate brightness with the tone curve. And there are “shadows” and “highlights”, which modify the tone curve. So I lower exposure using the DR modes, and adjust “brightness” with the Exposure Bias.

It gets me the JPEGs I want, and gives me reasonably-exposed RAW files with no blown highlights if I need them. I think that’s just the Fuji way of doing what you proposed.

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It should have three: aperture, shutter speed, and ISO. My X-T20 has these three. I adjust my aperture, have the shutter speed on auto, and the iso locked at 160. I then use the exposure comp dial to ETTR my exposure, usually -1 or so.

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Why don’t you just deactivate the setting for the scene referred workflow in the options or make your own preset in the exposure module?

I guess the preselected correction of the exposure bias is due to the users feedback of wanting a fast and more automated processing.

But regarding your observation of the different default values for white and black exposure in filmic I also wondered why these settings are chosen in contrast to the default settings of +4/-8 of filmic without the scene referred workflow preset. Especially the black level of -0.002 in the exposure module.

Funny, but by @anon41087856’s definition, that’s exposure, not brightness. As he said, exposure is about capturing light, while brightness is about the rendered JPEG (if I understood him correctly).

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Brightness is a “curve” like this:

Screenshot_20200824_215322

Exposure is changing the amount of light that enters the camera (diaph or shutterspeed), or simulating that change by an electrical gain (ISO setting, which electrically “multiply” the signal) or a digital one (exposure correction, which numerically multiply RGB values).

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So it sounds like what we need is for the modules to be able to expose an API that can be used by other modules to request information, and for modules to be able to publish updates to other modules that are interested. This sounds like some sort of message queue solution that supports subscriptions could be useful. I guess the first step is to understand what are the message flows we would want to support.

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To me, that’s a reason to have it disabled by default, rather than the other way around.

You’re making a deliberate choice on your exposure - processing software should not be trying to second-guess your intent.

I don’t agree. If the camera rendered the scene’s brightness correctly (people, grass, road), but blew out the sky, which is much brighter, then it’s not an ‘artistic decision’ on my part to apply -1…2EV, but a technical one (kind of what your Fuji does, and my Nikon does not do, or not as well). You could call it a ‘desparate choice’ instead of ‘deliberate choice’. :slight_smile: The sky is preserved, but the subject is recorded too dark. Then, loading the image into darktable, it’s very nice that the software can restore the correct exposure for the subject, while pushing the sky over ‘100%’, from where I can bring it back to display-land using filmic’s tone mapping.

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May I revive this old thread?

I totally agree that exposure is like microphone gain.

But exposure compensation as dialed-in in the camera is only one component of total exposure. That’s why I do not understand why in the filmic rgb workflow, the exposure module by default reverts camera exposure compensation.

I may arrive at the same exposure in multiple ways:

  • dialing-in exposure compensation
  • using auto exposure lock
  • using spot metering
  • shooting in manual mode

Only in the first case will the exposure module interfere. Isn’t this inconsistent?

Perhaps filmic assumes that the metering of the camera is to be trusted (and is used correctly by the photograph) and the exposure compensation dial is only used for ETTR?

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I think that sums it up well. To add to it slightly: you are using a raw processor, so it is assumed you are shooting in a manner that will enable you to get the best output image from processing the raw. And that leads to the assumption that the exposure compensation dial would be used for ETTR.

That is I have to say a very strange assumption. Five minutes after using a camera most people have learned that the camera metering must always be compensated. Not for SNR reasons but basic photography reasons. Besides subject and framing it’s the whole thing with photography.

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I agree. My DSLR is cheap and old. When left to its own automation, it overexposes just about everything.

Even a new super good camera can’t know how the photographers want to expose a scene. The decisions around exposure are as I mentioned a huge part of photography.

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Only you know what you shot, what your subject is, where it is located in the frame, and how you want it to look in the final picture. Would you like darktable to automatically figure out the correct exposure? Can you define what ‘correct’ exposure is?
Darktable is not sentinent. Relying on camera exposure as a sensible, close-enough default (or baseline) is, I think, understandable. You can always change it if it does not suit your way of shooting.

Thanks. I guess there’s no other way. Having two separate exposure correction dials (one artistic, one technical) would not work that well…

There are people here who are much more knowledgeable than me, but I think the assumption that exposure compensation was used for ETTR is implicit in filmic’s reversing that exposure compensation. And that clearly can conflict with raw files taken with the aim of getting a well-exposed SOOC JPEG.

That’s why we have presets and styles: if the defaults don’t correspond to your workflow, you can correct that.

But as there are about as many workflows as there are users, no default setting can satisfy everyone… (E.g. the standard +0.5EV exposure doesn’t fit my camera, but is that a reason to change the default? I trust the devs enough to pick a default that’s more or less correct for most users)

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For me and my Canon 80D the default +0.5 EV does pretty well. But I still don’t get why darktable should care how I did my exposure. The compensation is only a tool to get the exposure I want when I use a semi automatic mode. I could just as well have the same exposure in manual. The goal will always be the same, ETTR or not, and the only things that matter are the actual ISO, aperture and shutter speed, not which tools I used to find them.

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