Auto adjust ETTR exposure

DxO PhotoLab Feature requests
9

My interpretation is he wants a quick way to view the image at whatever the original settings were in his camera for the exposure. This is before he re-adjusted the exposure to over-expose, or under-expose. Whether or not this is useful is not the point - he just wants a quick way to view the scene "the way the camera saw the scene before he made changes to the settings.

Regardless of what the exposure was that the camera actually used, he wants to see the scene the way his camera saw the scene, without any changes.

If the camera records how much he over-exposed by (say, +1.7 stops) he wants to view the scene without those 1.7 stops, to see what the camera would have captured, had he not made any changes.

Or, the way I would think of this, does the camera record the “plus 1.7 stops” in the EXIF data". …and if so, he could view the image as usual in PL, find that value, and change his exposure in PL by lowering the exposure by 1.7 stops - same end result. Easier for everyone - but only if the “exposure change” was recorded in the EXIF data.

(Might or might not be useful in processing, but it would show what the camera wanted to do, before he did the +1.7 adjustment, which I think is what he wants to see on his screen.)

(I don’t think he wants to use this in processing - I think he just wants to see the change before and after the exposure compensation, on his computer screen. I would also like to be able to do that, not for processing, but just to show the difference, but if the exposure compensation is recorded in the EXIF data, as I see it, that’s all that is needed, and I can modify the exposure in PL by that amount.)

Aha! It does get recorded!
https://www.geofflawrence.com/photography_tutorial_exif_data.html

So, is this change listed in image data while using PL?

10

Except you never know what the right exposure was. See by example how Joanna sets the exposure.

George

11

But not only that. Before people had screens on the back of their cameras, we used to “place” an exposure to suit the film type and to maximise capturable dynamic range. Thus, “exposing to the right” of the available dynamic range.

ETTR, as you describe it, is a technique of letting the camera work out what it thinks is the correct exposure, taking a “test” shot, adjusting to move the histogram and trying again. If you are going to go to all that trouble, you might as well put the camera into manual mode and spot meter the scene correctly - then you will know exactly what the histogram will look like in processing without even looking at it on the back of the camera.

If I put Mike’s shot back into my camera, the in camera preview and histogram show…

IMG_1205
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Are you really saying that Mike should have placed the histogram further to the right? I’m sorry, but that would have simply blown the sky to smithereens.

Don’t forget the histogram you see on the back of the camera is that of the JPEG preview, not the RAW file.

Here is the JPEG extracted from Mike’s RAW file, as viewed in PL…

Capture d’écran 2021-10-23 à 10.36.15
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This is what the histogram on the camera was constructed from, not …

Capture d’écran 2021-10-23 à 09.09.32
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… which is the SOOC RAW.

It is incredibly important that you don’t base a RAW file’s histogram on what you see on the back of the camera. The only way to get reliably exposed RAW files that will process easily in PL4 is to get to know your camera, and measure the light correctly, according to the lighting conditions, using an appropriate metering mode, which for contre-jour shots is invariably spot metering

But never, ever over-expose a RAW image - you will never recover blown highlights.

1 Like
12

True, but he want’s the choosen by camera exposure.
Right exposure is “ETTR” level. But sometimes you expose accoording to a certain subject to get that right, like a face or group of people or… The right exposure is the one who give’s what you intended to get. :slightly_smiling_face:

1 Like
13

ETTR is just a trick to minimize noise by overexposing the image and later on correcting that again. The idea is that some noise is a constant of the sensor. By adjusting the overexposed image later one is also lessen the noise. Of course overexposing without clipping. Your histogram doesn’t have space left on the right side so you can’t use that trick.

George

14

In case of a camera with user settings it’s easy to store the equivalent setting
(exposure mode, metering mode, exposure compensation).

For example with the Nikon D750 → @mikemyers

  • Metering Modes (manual pdf p.167 / print p.139)
    • Center-weighted
    • Spot
    • Highlight-weighted → close to Auto ETTR
  • User Settings (pdf p.127 … / print p.99 …)

User setting [ U1 ]

  • Manual exposure
  • (normal) Spot metering
  • Exposure compensation fixed to +1 2/3

User setting [ U2 ]

  • Aperture priority
  • Center weighted metering
  • no (fixed) Exposure compensation

That way, one has 2 (3) different settings at hand.

15

Thank you, Wolfgang.

I think that the original poster wanted something that compensates exposure shifts automatically in PhotoLab and I answered with that in mind.

I’m sure that Mike will try your proposal…

16

Totally true, but we’re all assuming things - why not also tell him how to get the answer he was asking for, along with our better suggestions?

He just wants to see the photo he would have gotten, at the recommended settings, with no adjustments. Maybe he’s just curious, and wants to compare that the captured image would look like had he not made the adjustments? Maybe someone asked him to show that to them? It may not be a useful tool for anything, but I too would like to be able to see that, and now I know how, as long as the exposure compensation is captured in the EXIF data. :slight_smile:

That might be what he really wanted, but it’s not what he asked for, twice. He repeated himself to make sure there was no mis-understanding. To do what he asked for is trivial, once someone uses the “exposure compensation tool” and changes it to eliminate the exposure compensation he dialed into the camera.

17

Actually, having aired the discussion, it might be interesting to put a “hotspot” on the Exposure Compensation part of the EXIF palette that could be clicked on to “normalise” it.

What do folks think of that?

1 Like
18

Both false and true…

True: Blown highlights are gone and cannot be recovered. They can still be “improved” e.g. for printing by tone curve manipulations that you’ve illustrated a few times.

Not universally true: Never over-expose. Overexposing is common practice for bright low contrast subjects…

19

Hmmm. I remain unconvinced but open to examples of how this would work :wink:

20

You’re right, Mike.

I’d vote for a normalizer tool too, be it as proposed by Joanna and/or for something more universally applicable, like the normalizing tool that exists in Capture One (pick up a colour and apply it to a few images by clicking on the respective areas in these images)

21

It doesn’t “work”; it just shows him what he wants to look at, no more, no less.

(I wondered about doing that also, but didn’t realize how easily I could un-do my exposure compensation setting… I wonder about far too many things, but I only concentrate on what you suggest, as that’s something I always need to learn.)

22

Ok, got it :slight_smile: → ‘discard’ the camera’s exposure compensation setting, readout from metadata …

Being not very familiar with ETTR +1,7 (doing people and concerts, but seldom landscape) I don’t know really, if to simply revert the +1,7 in-camera-correction is suffcient.

Tried now with Mike’s pic, but also had to use SmartLighting spot weighted

Screen Shot 10-23-21 at 04.18 PM.PNG
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and Selective Tone / Shadows

Screen Shot 10-23-21 at 04.19 PM

To revert exposure correction didn’t work on it’s own → such a drop down option is questionable.

23

Yup. I always create a new VC before I do anything at all to an image. That way, I can go back or compare a VC with it at any time. If I want to try something out, without being sure of it, I just create another VC, try it out and, if it works, delete the previous VC and carry on from the new one.

That way I can select which previous version I want to compare the current one to when I press the Compare button.

24

ETTR was a technique originally developed for early sensors and is not even worth considering using on modern sensors. I read an article some some back which completely debunked ETTR for modern sensors.

I have never bothered with ETTR because my photography is generally wildlife and birds and you very rarely get the time to do ETTR. Besides, the noise reductions in PL now are so good that it gives way better results than what ETTR would give. Another thing that Joanna mentioned is that the histogram is for the jpg and not the raw so if you rely on the histogram to implement ETTR then you will not get the best results. Concentrate on your composition, the result you are after and the exposure you are after. ETTR gives you so little it is not worth even considering.

This is my opinion and I am sure I will take some flack for this but I hear of so many people trying to implement ETTR and miss the shot they are after in the process.

25

The Nikon has a “Highlight-weighted” exposure mode that I find very useful for shooting concerts

Capture d’écran 2021-10-23 à 16.19.25
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Now that is interesting. I tend to use the expression when trying to explain to “students” about placing exposure rather than get into too much complexity with explaining how the Zone System works when adapted to digital sensors.

Indeed. If you have to shoot, chimp, shoot, chimp, etc., it all takes time. On the other hand, getting to know your camera and its limitations will win you shots hands down.

26

see Auto adjust ETTR exposure - #22 by Wolfgang – addendum

27

There’s no figure you can use to correct the over exposed image. In the image from @mikemyers there is no overexposure. The +1.7 EVC is due to the way they determine the right exposure.

I didn’t know that. Must check that out.

George

28

Sure, it was about how to revert …

Highlight-weighted:
When I checked my cam, I realized this possible setting and had to look up in the manual
→ Auto adjust ETTR exposure - #14 by Wolfgang
So, I quickly took some shots – not precise, but to get an idea. And it looks like the measured Spot metering value is corrected by about 1 EV. I have to check more. :slight_smile:
Screen Shot 10-23-21 at 05.43 PM
Center weighted

Screen Shot 10-23-21 at 05.47 PM
Spot metering Highlight-weighted