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Author Topic: Adobe Camera Raw Smart Objects  (Read 1583 times)

Andy800

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Adobe Camera Raw Smart Objects
« on: August 21, 2020, 07:30:11 am »

I was watching a YouTube video the other day in which a well known US landscape photographer and teacher exported a raw file from Lightroom to Photoshop as a smart object - saying that this maintains full 32 bit raw computation in a Photoshop 16bit layer (I know it's 15bit+1).
His next move is to duplicate the smart object via copy, and to re-process this via ACR to favor the highlights in the sky, then use blend if to blend the new highlights into the image.  He then makes a stamp visible layer over the top so he now has 3 layers and then labels the layers as 32bit RAW virtual image, 32bit RAW virtual image and 16bit rasterized TIFF.

So I have to ask - is this correct? He has been saying this in his videos for more than year, and no one has asked him for verification - and I can't find any verification of this myself, though I may be looking in the wrong places!

I use Lr and ACR equally as much as I use Raw Therapee, and I know Raw Therapee uses a 32 bit float processing pipeline, but I thought the Lr/ACR process pipeline was 16bit.  The way I see it is that the 'bits' in this case are nothing to do with image bit depth but everything to do with adjustment accuracy and computation.

But it's frustrating me that I can't find anything to either confirm or refute the validity of the information in the video(s) the chap has made, so if the learned members of this forum can help then that would be great  :)
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digitaldog

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Re: Adobe Camera Raw Smart Objects
« Reply #1 on: August 21, 2020, 09:28:32 am »

The way I see it is that the 'bits' in this case are nothing to do with image bit depth but everything to do with adjustment accuracy and computation.
It's both but it's just math used to divide up the existing data and precision of the edits on that data.
If you have a pie that is 3lbs and you cut it into 16 or 32 slices, it's still a 3lb pie. You can divide up what you have as fine or coarsely as you wish.
Or put it this way; if you can edit the existing data you have in 8, 16 or 32 bits and produce the output (hopefully san's banding due to the edits), does it matter?
And yes, the path (math) used in whatever software will play a role. You can have a 10-bit document, editing in a 15+1 bit editor doesn't increase that bit depth of the original captured data.
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Andy800

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Re: Adobe Camera Raw Smart Objects
« Reply #2 on: August 21, 2020, 10:18:40 am »

Cheers for the reply, but it doesn't really answer my question - is the information in the aforementioned videos - HERE or HERE - correct or not? I didn't link the videos in my original post because it might seem a contentious thing to do, so please PM me if you feel it necessary - a simple yes it's correct or no it isn't would suffice.   
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digitaldog

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Re: Adobe Camera Raw Smart Objects
« Reply #3 on: August 21, 2020, 12:07:32 pm »

"32 bit is totally lossless unlike 16-bit or 8-bit" In about minute 4.

It's not lossless if edits are applied to rendered data. Now parametric edits produce RGB data and one could suggest it's lossless but that's got little if anything to do with bit depth since all raw data is 'high bit' (more than 8-bits per color). The raw's capture bit depth is what it is no matter what a software product may call it (15+1, "32"). The pie is still 3lbs no matter how sliced.

"It is a raw layer"
I have no idea what he's suggesting. If it's raw, it's raw. As a 'layer' if so (I suspect it isn't) or as a Smart Object. Now with an SO, you edit this parametrically in ACR. If it's indeed rendered as a layer in RGB, no matter the bit depth, edits will apply rounding errors. It isn't lossless. But because it's high bit (16 or 32-bit), it's moot; the edits do not apply damage that is ever visible at that bit depth or when printed.
Layers are not truly lossless anyway. Sure, while you are in Photoshop, you can always revert an edit (you can do a Save As too and the original did not undergo data loss). But at some point, outside of Photoshop, layers must be flattened and the data loss, moot or not, will exists. IF you print the image from Photoshop, PS has to flatten all the data to make the print. So same condition.
This talk of 'lossless' is mostly marketing hype and misunderstanding of what, how and where data loss occurs. Outside parametric edits, any edits to any RGB data in any bit depth will undergo 'some' data loss. The edits and if it's visible is the key here.

He seems somewhat confused by the ACR Histogram too. The fact is, ACR has highlight recovery IF (bit if), one or two channels is clipped. But the only way know how much or how little is to examine a raw Histogram which ACR, Photoshop, LR etc cannot provide. Highlight clipping in raw is based upon Exposure and that means the amount of light striking the sensor (or film), nothing else (including ISO). The way to view exposure of raw is by viewing a raw Histogram in a product like RawDigger. So there's some minor Highlight recovery in the ACR engine. There is its Histogram which is always based not on the exposure or the actual raw data, but based on the current rendering settings applied.

"So here is a 32 bit raw file". 5:15 in to the video
No, the raw file's bit depth is what it is.

"Not rasterized yet"
Well mostly yes and a little no. It hasn't been fully rendered from the original data, there is a preview that's rasterized so you can see what you've done so far. But then that's true too of the SO from raw; not rasterized yet, maybe never until the SO and other layers are flattened.

Look you can take ONE raw file, in its native bit depth and render it multiple times to blend it as you desire. There's nothing new in what this guy's showing here. You can't recover highlight data that's fully clipped due to true over exposure of the raw and visible with a raw Histogram. He's taking a very old concept (multiple rendering and blending of one raw) and adding some complexity by speaking of bit depth etc.
IF you have a 12 bit raw capture with clipped highlights, that's what you have, no matter how ACR or Photoshop slices up that pie. You gain no more highlight data or recovery using more bits; it's there or it isn't.
Now IF you bracketed the shot, then used multiple raws, that's a totally different technique and process but again, the recoverability isn't due to the bit depth per se, it's due to the data actually being in one or more of the raws.
All this talk of "Raw Layers" and "32-bit" in the video kind of reminds me of an old saying by the late, great Bruce Fraser:

"You can do all sorts of things that are fiendishly clever, then fall
in love with them because they're fiendishly clever, while
overlooking the fact that they take a great deal more work to obtain
results that stupid people get in half the time. As someone who has
created a lot of fiendishly clever but ultimately useless techniques
in his day, I'd say this sounds like an example."


Bruce Fraser
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fdisilvestro

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Re: Adobe Camera Raw Smart Objects
« Reply #4 on: August 21, 2020, 06:07:26 pm »

The smart objects are not 32 bits, the raws are not 32 bits. Now if ACR or LR do the math in 32 bits floating point or not, I cannot prove, but my guess is not.

Besides the obvious tests, which the author disregards, to tell if a layer / image is 16 or 32 bits (image tab or file info), just try the "Filter menu" and you will see that all filters are active, which does not happen in 32 bit files.

Second, going to Photoshop to apply only global edits? Seriously? The same thing that he achieves by creating the second smart object and then "Blend if" can be achieved with "Range mask" directly in LR.

The last step in the first referenced video, which is to stamp a new layer on top with the visible content to then apply a levels adjustment because he had "Room in the histogram" is absurd. First, the same thing could be achieved with an adjustment layer, whitout the need of creating a new bitmap layer (increasing unnecesarily the file size). Second, that adjustment should have made in ACR or LR beforehand. Even if it were true that the smart objects were 32 bits, all would have been lost when he created the stamped layer to then adjust the levels.

One additional note: I find the term "Rasterize layer" that Photoshop uses as a poor choice of words. The content of the smart object in this case is already a raster image. I suppose this is a legacy term, used to convert "vector" graphics or texts to bitmaps, and they (Adobe) keep applying it to smart objects regardless of the content of the smart object itself.

Anyway, "32 bit raw virtual image" is nonsense to me.

Andy800

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Re: Adobe Camera Raw Smart Objects
« Reply #5 on: August 22, 2020, 10:13:40 am »

Andrew, many thanks for clearing that up for me - I thought I was going mad  8) And yes, double processing has been making my life easier for years.

Frank - yes, it's the math bit that I was wondering about.
I had always assumed Lr/ACR was 16bit math, but once I got heavily into Raw Therapee with its 32 bit float pipe it set me wondering about the truth of Lr/ACR, and whether or not it could actually be 32 bit math after all.
The way I 'understood' what he was saying was 'it's 32 bit math on the raw file" and all I've been wanting was confirmation of that fact one way or the other.

Again, Andrew and Frank, many thanks for your replies  :)
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fdisilvestro

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Re: Adobe Camera Raw Smart Objects
« Reply #6 on: August 22, 2020, 05:49:37 pm »

The last step in the process makes all that irrelevant
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