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Question

ACR (adobe camera raw)/LR vs PS shadow/highlight adjustment?

Forum|Forum|7 years ago
August 31, 2018
9 replies
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Just curious what the difference is between both. I see most photographers use Lightroom and a few use only Photoshop and know they use ACR within PS and also the shadow/highlight adjustment. What I find even more interesting is the fact that sometimes using PS shadow/highlight adjustment, you can squeeze more information from the shadows and then use curves increase contrast because the image becomes super flat afterwards. Is there any benefit/negative to using shadows/highlights adjustment in PS compared to using ACR?

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Hannibal ChangAuthor

Participating Frequently

how would I go about testing that though? Is there a way to tell how many stops I'm able to pull in correspondence to perhaps, how much shadow I can recover in Lightroom? Because I honestly cannot tell.

Yeah I have had my sigma ever since I was still a Canon shooter but after selling my Canon, got the A7ii then purchased a Zeiss 55mm 1.4. Both are incredible lenses. Just missing a 70-200 L lens from Canon now (Sony is just too expensive for what it is) as I currently have the F4 non L lens but I snatched it for $100 and given the right timing, still puts out incredibly sharp photos.

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Hannibal ChangAuthor

Participating Frequently

Hang on, how do you know how many stops of DR you have? People always tell me how many stops I have and I keep responding with I have no clue how to actually tell the difference when shooting. Only way I can is by looking at the light meter and adjusting in PP from there, so in a sense I can actually only tell how many stops I have based on my light meter haha.

D Fosse

Community Expert

https://forums.adobe.com/people/Hannibal+Chang wrote
Hang on, how do you know how many stops of DR you have?

That's a property of the sensor, how many times you can go from threshold and double the amount of photons before the sensor reaches saturation point. Sony claims 14 stops, and I see no reason to doubt it. I'm duly impressed with this sensor. It clearly outperforms the Nikon D810.

BTW, the Sigma Art line is outstanding. I have the 24/1.4 and love it. In most lens tests these days, you'll find the 35/1.4 at the top of all rankings. It's considered the reference 35mm. As I wrote in another thread in the lounge, Sigma is about to become the Carl Zeiss of the East. They just need to up prices a bit and get rid of the old "knockoff" image - and I suspect that's what they're in the process of doing.

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Hannibal ChangAuthor

Participating Frequently

I see what you're saying with your A7RII. I have an A7ii and shooting with a sigma art, the combination itself gives me an incredible dynamic range but wish I had more, I'm always almost pushing highlights right before they blow out, nearly max out the shadows [to 95 in LR], then bringing the exposure down to 'normal'. However, for what I shoot, I don't expose for the overall photo, I expose based off of my subject (I'm an automotive photographer so I expose based on the vehicle).

Stephen Marsh

Community Expert

These old white papers from Adobe provide a fundamental background to some parts of this discussion:

https://www.adobe.com/digitalimag/pdfs/understanding_digitalrawcapture.pdf

https://wwwimages2.adobe.com/content/dam/acom/en/products/photoshop/pdfs/linear_gamma.pdf

https://www.adobe.com/digitalimag/pdfs/highlight_recovery.pdf

Raw sensor data has the obvious advantage in highlights, with an equally obvious disadvantage in the shadows. With the ability to render the raw data into a standard RGB gamma colour space, raw data has great benefit for exposure challenged images. It is also possible to make a secondary render into a non-standard RGB gamma that may provide more latitude for working the shadows using the Shadow/Highlight tool.

I agree with “both sides” – that not all tools are equal and that there are different places and different tools that perform similar but differently. The right tool for the right job at the right place and the right time!

D Fosse

Community Expert

I think it depends a lot on the camera sensor. Doing highlight recovery in ACR from a 14-year old Nikon D70, or a phone camera for that matter, might not yield very spectacular results.

My example above was shot with a Sony a7RII, which has a staggering 14-stop dynamic range. This means you can push exposure way beyond what you would normally even consider, and still effortlessly recover highlights that would appear totally blown out. I thought my Nikon D810 was good, but the Sony beats it hands down. It's just a newer sensor.

At the same time, Stephen is right that this is nowhere near as effective in the shadows. The linear TRC of a raw file means that the vast majority of the recorded levels are up there in the highlights.

But OTOH it does indirectly benefit the shadows - because you can give more overall exposure without blowing out the highlights. So taken as a whole production chain, the ACR highlight recovery also, as a side effect, gives you less noise and better separation in the shadows.

At the bottom of it all lies this: a rendered file uses only a subset of the data available in the raw file. It's a one way street.

D Fosse

Community Expert

BTW, to fully appreciate what a 14 stop dynamic range means, consider that transparency film had about 5 stops, and B&W negative film at most 10. Ansel Adams' famous zone system was based on a 10 stop range, and he used slow large format negatives.

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Hannibal ChangAuthor

Participating Frequently

but in a sense, which one would give you more of a dynamic range without killing color? based on D Fosse's example, using highlights/shadows adjust to kill highlights literally desaturated the highlights and ACR retained color but the few times I used solely highlights/shadows adjustment, I didn't notice a difference. In D Fosse's example, it does look as if the picture's rendered data was modified and not the raw data itself.

davescm

Community Expert

Raw data is never modified - the rendering from that data is modified.

ACR/Lightroom can do genuine highlight recovery by taking data from a single raw channel and recovering luminosity from that one channel. This would put detail into a blown sky, for example, as grey detail. Working with rendered RGB data cannot do the same.

Dave

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Lumigraphics

Legend

:sigh:

Lets not miss my ORIGINAL point which is that its NOT either/or. These are different tools, they do NOT do the same thing, they do NOT have the same usage, and fighting a straw man is not helpful.

OP, both ACR and Photoshop have useful tools. Don't let anyone try to distract you by veering off into nonsense arguments.

D Fosse

Community Expert

From the original post:

Is there any benefit/negative to using shadows/highlights adjustment in PS compared to using ACR?

That question has been answered.

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Lumigraphics

Legend

i answered in the first reply.

This has turned into someone asking if it better to eat using a fork or a knife and you claiming that a fork is always the right answer.

You can ignore my point if you have to be “right” but your answer is incomplete. Now let’s quit clogging the dead horse shall we?

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Lumigraphics

Legend

OP- just take this away. These are different adjustments that do different things. Its not a choice of using one or the other, its picking the right tool for the job.

D Fosse

Community Expert

Lumigraphics wrote
These are different adjustments that do different things. Its not a choice of using one or the other.

Of course they are different adjustments, one works on raw sensor data and the other on rendered RGB data. Those are very different things. But they both attempt to accomplish the same thing: highlight and shadow recovery. Which is what the OP was asking about.

The original point still stands - highlight and shadow recovery are both more effective and less damaging, executed on raw data in ACR. That is so well established by now as to be almost an axiom. You're the only one disputing it that I've heard of in recent times.

Of course nobody's stopping you from masking the result in Photoshop, if that's what you were concerned about.

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Lumigraphics

Legend

ACR does coarse global adjustments. And it’s not recovery, it’s setting the level of a tonal range.

The Photoshop effect is different. Not the same thing. It doesn’t work the same way or yield the same results.

If you want a coarse global adjustment, you do that in ACR. If you want targeted recovery with more settings to adjust, you use Photoshop.

I’m not sure why you are putting words in my mouth and being combative but please stop. You are claiming that I’m “disputing” something which I never said.

Oh and you can’t mask a global adjustment that you made before you opened a file in Photoshop, so I’m not sure where that comes from.

So, OP... it’s not either or. im not sure why some commenters are posing it as such but you use the programs at different times in the process for different things and you will get different results.

D Fosse

Community Expert

Doing this in Photoshop, you're working with rendered RGB data, a very limited subset of the original raw sensor data. You may be able to get the effect you're after, but at the price of grain and artifacts, simply because you're stretching limited original data.

Doing it in ACR, you have the full sensor data at your disposal. That means you can make much more extreme adjustments without noticeable image degradation. Shadows and highlight adjustments in ACR are image adaptive. It's not a "fixed band", the effect and depth depends on image content.

In short, you should absolutely do this in ACR if you want the best quality.

There is a golden rule for all of these things, which applies to the whole chain from original scene to final output: Do everything as early as possible in the process. Do as much as you can in ACR, then move to Photoshop when ACR adjustments are exhausted.

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Lumigraphics

Legend

Sorry but I disagree with most of this.

Highlight/shadow in Photoshop is more like a filter. In ACR, it absolutely is a tonal range. Move your mouse across the histogram and it shows you what brightness level of the image will be affected.

As for applying adjustments early as possible, that’s is NOT a rule. Apply them in the order that you need. Altering shadow level in ACR is global while in Photoshop you can select a particular area to adjust.

D Fosse

Community Expert

I think you'll find that the consensus is clear about this. You have much more editing latitude with the raw data, than you have with RGB data. There is no point in arguing about that.

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Lumigraphics

Legend

Highlights and shadows in ACR covers a specific tonal band which cannot be adjusted. If you put your cursor in the histogram area and move it across, you'll see what tonal range the adjustments cover. All you can change is the level of that tonal band.

In Photoshop, you can use masks, complex selections, you can change the highlight/shadow parameters, you can Fade the effect after you apply it, you can apply it to a single layer (I often use it on a duplicate layer which I blend in.)

Other than the name, these are really two different things.

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