Link between in-camera exposure adjustment and RAW adjustment

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Idea for Lightroom & the RAW converter - if the EXIF data shows an exposure compensation value from in-camera, the exposure slider could reflect this. Eg. -2 in-camera starts the slider at -2
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Ryan Riopel

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Posted 7 years ago

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jdv, Champion

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The assumption is that this value is stored in something like ExposureBiasValue, and isn't one of the many proprietary fields that wouldn't be there for most cameras, or would require scanning the various vendor-specific blocks.
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Ryan Riopel

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Adobe already reverse engineers the whole RAW format for each camera. How much more work can it be to figure out which field the exposure bias is stored in?

And as far as I can see, Canons use ExposureBiasValue
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jdv, Champion

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Not quite.

Adobe decodes the raw info, and either reverse engineers or has permission to decode necessary things like white balance.

In order to do further stuff, only some of the many, many ways vendors abuse EXIF is decoded, and there are all sorts of fall-back situations they have to take when doing so.

The core of EXIF is treated as if it is standard (it isn't) but the various vendor additions and private blocks are, generally, ignored. The reason for this is that chasing them is a fool's errand.They are subject to change, are not intended to be shared beyond vendor software, and are generally a huge development and testing pain in the rear.

I'm not saying this isn't a good idea from a user POV, but Adobe is constrained by realities of the situation here.
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Steve Sprengel, Champion

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In your example with a camera EC of -2, are you asking that LR/ACR's exposure slider be centered on -2 and have a range of -6 to +2 which is just changing the labels under the slider, or are you imagining the exposure slider being set to -2 and have the same range as now of -4 to +4, which would limit the negative adjustment range to -2 stops and expand the positive adjustment range to +6 stops?

The first instance is just changing the labels under the slider, the purpose and usefulness of which is not clear, and the second instance is limiting the adjustment range on one end or the other, which seems less than good if the exposure was done correctly.

The other day I took a picture of a hummingbird resting on an old trumpet vine branch in between making the rounds of all the flowers. The hummingbird was illuminated by overhead cloudy lighting, but almost the entire background was in the shade under the trumpet vine. Because the average scene was overall darker than mid-tone, I set my camera EC to -1 to avoid washing out the hummingbird, and the hummingbird came out exposed correctly.

Just because I purposely set my EC to get a proper exposure. I don't want LR/ACR limiting my exposure adjustment range on one end or the other because of this. I also don't see the need relabel the exposure-slider values based on my use of the camera EC which is relative to the camera's light-meter that I really could care less about now that I'm adjusting the photo in LR/ACR.

LR/ACR's exposure slider should be telling me how much correction I have applied to the photo, not where the camera's light-meter guessed the overall scene midtone was.
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Ryan Riopel

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I definitely agree with the limiting of the adjustment range... What if there was just a little mark on the slider to note the bias? Seems like the best of both worlds, no?
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Steve Sprengel, Champion

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You say you agree with the limiting of the adjustment range. Are you agreeing that your original request would limit the exposure range and therefore would be bad idea, or are you saying you want the exposure slider range limited merely because the camera EC value was non-zero?

Assuming you are agreeing that limiting the slider range is not good, then regarding having a mark on the exposure slider scale to indicate the camera EC, to be relavent to the LR/ACR exposure slider operation, it would need to be in the opposite direction from the camera adjustment. For example, if the camera EC was -2, then the LR/ACR exposure slider having a mark at EV+2 would mean that if you move the exposure slider, here, you'll see the scene as the camera's light-meter guessed it should be exposed, which while perhaps being interesting sometimes, I can't see the usefulnes of, in general.

If you're saying that a camera EC of -2 should result in the exposure slider having an extra mark at -2, then why would this be a good idea? Moving the exposure slider to that mark would make things even more dark. If you merely want the EC value displayed, somewhere, then just ask for that, rather than mixing it in with the LR/ACR exposure slider that really has nothing to do with it.
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Ryan Riopel

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Yes, sorry, I meant that I agree it would be a bad idea to limit the range of the adjustment.

I also agree with having the mark in the opposite direction, so that it could be adjusted to see the camera's light meter's guess.
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Steve Sprengel, Champion

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The camera's EC is displayed in Bridge for my Canon DSLR so it shouldn't be that much of a problem for some cameras.

The biggist issue is that while you would like to see the inverse-EC indicated on the Exposure slider so you can play and see what the camera light-meter thought, this is really not something that is critical to photoprocessing in LR or ACR and more of a curiosity for you at the current time, but after a while, you'd probably not learn anything new until you got the next camera or lighting equipment and wanted to see how well the camera performed, again.

About the best you could expect to see is Adobe might add the EC alongside the few bits of information exposure information they currently display below the histogram, now. Personally, I'd like to be able to configure another line or two of customizable information from the metadata, perhaps Camera or EC or Flash or metering mode or whatever I had a particular curiosity about at a point in time, but I would't want Adobe to pick what they thought was the most important item out of the vast set of possible things based on a particular user's wants at the moment.
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Chris Cox

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OK, aside of decoding the metadata: you're confusing 2 unrelated things.

The camera exposure compensation changed the time or aperture relative to how the camera metered the scene. That change is now present in the time and aperture metadata, and baked into the raw data captured.

The exposure slider in ACR does not reflect the exposure compensation from the camera, and has nothing to do with the exposure compensation from the camera. The slider in ACR is an additional correction that you can apply to the raw data that you have already captured.

The slider in ACR should not show anything from the camera exposure compensation - because what the camera metered and how you compensated no longer matter at all. You have the image you have, regardless of how it was metered.

If you want to see how the light meter thought the scene should have been captured - that should be in the metadata. And it already is because it's the negative of the exposure compensation value.