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Raw & Post Processing, Printing => Adobe Camera Raw Q&A => Topic started by: AFairley on February 24, 2010, 02:12:04 pm

Title: Color space/bit depth in ACR
Post by: AFairley on February 24, 2010, 02:12:04 pm
I read the following statement about Lightroom:  

ALL editing is Lightroom is always 16bit per component in the ProPhoto RGB color space, regardless of the original file's colorspace. That's the working colorspace, and it is not changeable. Since ProPhoto RGB is a proper superset of all other colorspaces, this is a lossless transformation.

Is that what happens in ACR, and the bit depth and color space settings that are indicated on the clickable link underneath the preview window applied only upon export to file or opening in Photoshop, or is the image converted to the selected color space/bit depth on import to ACR?  I would expect the former, but want to be sure which it is.

Are RAW files, JPEGs and TFFs treated the same way?  

Thanks
Title: Color space/bit depth in ACR
Post by: michael on February 24, 2010, 02:53:54 pm
Yes, and yes.

Think of 16 bit ProPhoto as a big mixing bucket into which your files are poured. When you work on them the bucket is big enough that nothing slops over and falls on the floor. When you then export it's up to you to decide what space they should be in depending on how they will be used.

Michael

Title: Color space/bit depth in ACR
Post by: AFairley on February 24, 2010, 03:13:37 pm
Thanks Michael, appreciate the response.  I would have been very suprised if it was otherwise.
Title: Color space/bit depth in ACR
Post by: Schewe on February 24, 2010, 03:29:06 pm
Quote from: AFairley
ALL editing is Lightroom is always 16bit per component in the ProPhoto RGB color space, regardless of the original file's colorspace. That's the working colorspace, and it is not changeable. Since ProPhoto RGB is a proper superset of all other colorspaces, this is a lossless transformation.

To be precise, Camera Raw/Lightroom use it's own internal color space based on Pro Photo RGB color coordinates in a linear (1.0) gamma. So, to call it "Pro Photo RGB" is incorrect. And yes, it's a huge color space but it would also not be correct to call a transform from an existing color space into the ACR/LR color space lossless. It's not lossless, but it _IS_ optimal and any data losses would be very, very minimal.
Title: Color space/bit depth in ACR
Post by: fredjeang on February 24, 2010, 04:16:08 pm
sorry for my ignorance, but I do not understand one point.
We have a super and safe space color to work with in 16bits, but then, wich monitor is able to
reproduce al this spectrum?  
So we work in a great color space but we can not see all of it, and hardly reproduce them either.    

If I understand something, the reason would be that working the file in ProPhoto RGB space, some colors that have been captured
by the camera may possibly be visible on screen, if for example onces wants to push a red.
Is that correct? Then, after pushing where you wanted, onces export in a color space that is compatible by the printer, or the web?

I do not get it.

Fred.
Title: Color space/bit depth in ACR
Post by: Schewe on February 24, 2010, 07:20:46 pm
Quote from: fredjeang
sorry for my ignorance, but I do not understand one point.
We have a super and safe space color to work with in 16bits, but then, wich monitor is able to
reproduce al this spectrum?

No printers can print all of it either...but Pro Photo RGB (the real color space) is an ideal archive and master RGB color space because it's the ONLY color space that CAN contain all the colors your camera can capture in raw AND all the colors that recent prints can print.

For a long time, displays were limited to sRGB or less...then came displays capable of all of the Adobe RGB color space...

It used to be that ink jet printers couldn't print any colors outside of sRGB...now recent 10 & 12 color printers can print colors outside of even Adobe RGB...

So, the ONLY color space to future proof your images is Pro Photo RGB....and the ability to contain all the colors a camera can capture is also why Thomas Knoll chose the PP RGB color coordinates for Camera Raw and Lightroom.



Title: Color space/bit depth in ACR
Post by: digitaldog on February 24, 2010, 08:36:01 pm
Quote from: fredjeang
So we work in a great color space but we can not see all of it, and hardly reproduce them either.  


If your final output is a display, thatís an issue. Based on what Jeff said in terms of the gamut of modern printers, you have a choice. Dumb down (reduce the gamut) so you can see, all the colors and be unable to print them, or not see those colors that are there, but use them when you output the color. Most of would rather have option #2.

FWIW, thereís a nice chunk of ďcolorsĒ (quotes on purpose) defined in ProPhoto RGB that fall outside human vision. Some would say if you canít see them, they are not colors but thatís another discussion.
Title: Color space/bit depth in ACR
Post by: Eyeball on February 24, 2010, 09:17:18 pm
I use ACR, not Lightroom, and in ACR the colors DO change inside the ACR window depending on what colorspace is chosen.  I see this in the actual color as well as when the clipping indicators are turned on.  I just wanted to clarify that because I think one could get the impression from the dialogue above that NO change is made to the image for colorspace until the image is saved or moved to PS.

Is that the way Lightroom behaves also?
Title: Color space/bit depth in ACR
Post by: digitaldog on February 24, 2010, 09:30:45 pm
Quote from: Eyeball
I use ACR, not Lightroom, and in ACR the colors DO change inside the ACR window depending on what colorspace is chosen.  I see this in the actual color as well as when the clipping indicators are turned on.  I just wanted to clarify that because I think one could get the impression from the dialogue above that NO change is made to the image for colorspace until the image is saved or moved to PS.

Is that the way Lightroom behaves also?

No because unlike ACR, you donít define the encoding color space until you export (or open in Photoshop). The numbers and histogram are based on Melissa RGB, while in ACR, those numbers and histogram (and clipping of course) is based on what you select in the workflow options.

That said, I donít recall seeing a change in color or tone of the image when toggling the various color space options in ACR. The numbers and histogram, yes indeed.
Title: Color space/bit depth in ACR
Post by: Eyeball on February 24, 2010, 09:44:50 pm
Quote from: digitaldog
No because unlike ACR, you donít define the encoding color space until you export (or open in Photoshop). The numbers and histogram are based on Melissa RGB, while in ACR, those numbers and histogram (and clipping of course) is based on what you select in the workflow options.

That said, I donít recall seeing a change in color or tone of the image when toggling the various color space options in ACR. The numbers and histogram, yes indeed.


That's what I thought.  So the answer to one of the OP's original questions is "yes, there is some difference in colorspace handling between ACR and Lightroom."

And yes, the colors do change in ACR.  I double-checked before posting.  The degree to which the change is visible would likely depend on the extent of any clipping and the gamut of the monitor but it changes.  I would never attempt even a minor correction of the likes of Michael Reichmann, Jeff Schewe, and Andrew Rodney unless I had double-checked and verified.
Title: Color space/bit depth in ACR
Post by: digitaldog on February 24, 2010, 09:47:15 pm
Quote from: Eyeball
And yes, the colors do change in ACR.  I double-checked before posting.

So did I and I canít see it...

The processing color space is the same. The encoding color space might be the same, it might not. Lightroom actually provides more options (you only get four in ACR).
Title: Color space/bit depth in ACR
Post by: Tim Lookingbill on February 24, 2010, 10:06:26 pm
If you have a wide gamut monitor and create certain intense cyans, yellows and oranges in ProPhotoRGB there will be a slight but noticeable shift converting to sRGB.

To see this create a 100% cyan fill in a new standard SWOP v2 CMYK document in Photoshop. Convert that to ProPhotoRGB, then convert to sRGB and watch the cyan gain a bit of magenta and lose intensity. Same thing happens to intense yellows and oranges. This is the most shift you'll ever see converting from ProPhotoRGB to sRGB. If you see something greater, then their something wrong under the hood somewhere or you're working on a low gamut laptop.
Title: Color space/bit depth in ACR
Post by: Eyeball on February 24, 2010, 10:19:44 pm
Quote from: tlooknbill
If you have a wide gamut monitor and create certain intense cyans, yellows and oranges in ProPhotoRGB there will be a slight but noticeable shift converting to sRGB.

I was looking at a shot I took of Monarch butterflies in Michoacan, Mexico, so I think we're on the same track.  I don't have a wide-gamut monitor but I had to zoom to 100% and look carefully to see the change.  At first I thought it was affecting the clipping indicators only.
Title: Color space/bit depth in ACR
Post by: Schewe on February 25, 2010, 12:45:49 pm
Quote from: Eyeball
And yes, the colors do change in ACR.  I double-checked before posting.  The degree to which the change is visible would likely depend on the extent of any clipping and the gamut of the monitor but it changes.  I would never attempt even a minor correction of the likes of Michael Reichmann, Jeff Schewe, and Andrew Rodney unless I had double-checked and verified.


Only the preview and the RGB numbers change in the Camera Raw dialog...the image doesn't change till you actually render the image into Photoshop...otherwise while the raw image is open inside of ACR the underlying processing pipeline keeps the image in the exact same color space regardless of the Workflow Settings.

The last set before opening in Photoshop is a color space transform from the processed file in the ACR color space to the final output profile set in the Workflow Settings...
Title: Color space/bit depth in ACR
Post by: Peter_DL on February 25, 2010, 04:02:15 pm
>>That said, I donít recall seeing a change in color or tone of the image when toggling the various color space options in ACR. The numbers and histogram, yes indeed.<<
Quote from: digitaldog
So did I and I canít see it...
Yes, it can happen, devinitively.
I'm seeing it with sunsets. Subtile though.

I think it's once changing to sRGB output
while 1.0 pRGB > monitor gamut > sRGB for the relevant colors.

Histogram changes once changing to sRGB output
and it seems that the Preview pathway changes as well.

Peter

__
Title: Color space/bit depth in ACR
Post by: FranciscoDisilvestro on February 25, 2010, 08:45:18 pm
From my experience I also see changes in colors in ACR when I change color space from ProphotoRGB to sRGB. It happens in those areas that are out of gamut in sRGB. It is the same change in color as opening the image in PS in ProphotoRGB and then convert to sRGB

Iīm using ACR 4.6, on Windows XP.
Title: Color space/bit depth in ACR
Post by: Schewe on February 25, 2010, 09:05:14 pm
Quote from: FranciscoDisilvestro
From my experience I also see changes in colors in ACR when I change color space from ProphotoRGB to sRGB.

Again, what you are seeing is in effect, soft proofing of the final output color space...in point of fact you are NOT seeing the impact of the final output color space of the raw processing pipeline because that doesn't change regardless of the output space...you are only seeing the preview and RGB numbers of the final color space.
Title: Color space/bit depth in ACR
Post by: FranciscoDisilvestro on February 25, 2010, 09:11:05 pm
Thanks, It makes a lot of sense
Title: Color space/bit depth in ACR
Post by: FranciscoDisilvestro on February 25, 2010, 10:22:09 pm
Thinking about it, If ACR does softproofing (which I'm sure after Schewe explanation), why would you think Adobe did not included it in Lightroom?
It seems to me that it is probably the only one thing missing in the LR print workflow.
Title: Color space/bit depth in ACR
Post by: Schewe on February 25, 2010, 11:52:18 pm
Quote from: FranciscoDisilvestro
...why would you think Adobe did not included it in Lightroom?

To be accurate, it's soft proofing of one of 4 color spaces only...that's NOT the same as soft proofing to arbitrary output profiles...

Yes, I would like real soft proofing in Lightroom...it would save a lot of trips into Photoshop. But I do tend to go into Photoshop for a lot of the retouching chores I need to do so it's not a deal breaker for me.

The bottom line is if you want the best possible output, you'll need to be doing final image optimizing in Photoshop even if only for the last 5-10% of you final imaging...those people who keep harping on getting EVERYTHING in Lightroom fail to understand that Lightroom will NEVER completely replace Photoshop and it's foolish to expect or demand that...

Lightroom for parametric editing, Photoshop for pixel editing...use the right tool for the job at hand.
Title: Color space/bit depth in ACR
Post by: ErikKaffehr on February 26, 2010, 01:04:42 am
Hi,

Monitors may improve with time. Now we essentially have monitors covering Adobe RGB, and future monitors may cover even wider gamuts. Wider gamuts would probably require higher resolution of color tones like 10-bit or 12 bit. According to Karl Lang it is already an issue with Adobe RGB that one bit change can cause a significant change in tonality. For that reason some experts advocate using sRGB if the colors in the image don't fall outside sRGB.

Essentially, use sRGB for weddings and Adobe RGB for flower shots ;-)

Cameras have a pretty wide gamut (although gamut may not be the correct term) so the raw image contains a lot of colors falling outside sRGB and Adobe RGB. So once you truncate the colors in the raw image to a smaller RGB the colors falling outside are gone (If you use a parametric workflow you would always use the original image, so this doesn't apply). Printers can yield colors outside Adobe RGB, but cannot handle all colors in sRGB. Think of this as a screen having a gamut like a cube, and a printer having a gamut like a potato. A potato can be smaller (have a smaller volume)  than the cube but still would not inside the cube.

Unfortunately, sRGB is established as a replacement for color managed workflow. Most people have uncalibrated screens somewhat similar to sRGB, most pictures don't have embedded profiles and most viewers do neither handle screen calibration data nor embedded profiles. So using a wide gamut image is not very feasible unless both sender and receiver know what they are doing.

If we have images in a wide color space we also need high bit file formats. The wide gamut spaces are not very efficient, much of the "binary space" is wasted on non existing or non visible colors. Converting between spaces introduces some round off errors, having more bits can help with that.

One advantage with using ProPhoto RGB is that it is quite obvious if color management is missing. With Adobe RGB you can loose profile and think it's sRGB and still get away with it.

Best regards
Erik




Quote from: fredjeang
sorry for my ignorance, but I do not understand one point.
We have a super and safe space color to work with in 16bits, but then, wich monitor is able to
reproduce al this spectrum?  
So we work in a great color space but we can not see all of it, and hardly reproduce them either.    

If I understand something, the reason would be that working the file in ProPhoto RGB space, some colors that have been captured
by the camera may possibly be visible on screen, if for example onces wants to push a red.
Is that correct? Then, after pushing where you wanted, onces export in a color space that is compatible by the printer, or the web?

I do not get it.

Fred.
Title: Color space/bit depth in ACR
Post by: AFairley on February 26, 2010, 12:07:11 pm
Quote from: Schewe
Lightroom for parametric editing, Photoshop for pixel editing...use the right tool for the job at hand.

Jeff, if I can drift OT for a moment....  Why would you use Lightroom instead of ACR for parametric editing if you are going pixel edit in PS anyway.  LR always has seemed redundant to Bridge/ACR/PS to me (unless one wants the image management and printng engine available in LR, nether of which justify the expense to me).  Is there an advantage to parametric editing in LR vs ACR?
Title: Color space/bit depth in ACR
Post by: Schewe on February 26, 2010, 12:28:04 pm
Quote from: AFairley
Is there an advantage to parametric editing in LR vs ACR?

In terms of the actual editing, no difference at all (other than the fact that Lightroom is a "bit" more usable due to having as many panels open at once as you like).

There is a big difference in terms of being able to FIND my raw files however and after any final Lightroom edits followed by Photoshop edits I keep all my master print files in Lightroom because I greatly prefer to print from Lightroom instead of Photoshop.

I don't have any problems however, using either Lightroom or ACR/Bridge...it all depends on what I'm doing at the moment. If all I want to do is open a raw image and look at it, I would prolly simply point Bridge to the folder it's in and use Camera Raw...

What I don't do much of however is try to alternate back and forth between Camera Raw and Lightroom for edits...it can be done as long as you remember to save out the .xmp from Lightroom after an edit and then read the .xmp from the file after a Camera Raw edit...but that quickly becomes a problem keeping track of the last edit.
Title: Color space/bit depth in ACR
Post by: Peter_DL on February 28, 2010, 06:42:31 am
Quote
... Camera Raw/Lightroom use it's own internal color space based on Pro Photo RGB color coordinates in a linear (1.0) gamma.
Another question is, if such rigid editing space i.e. 1.0 pRGB ("linear gamma" ProPhoto RGB)
was really a good choice.

I tend to conclude that the editing space should be limited and change to the gamut primaries of the selected output space, even down to sRGB if needed (while keeping it at "linear gamma" in ACR). Thus, avoiding to have too much Oog colors created in the course of image editing.  Out-of-gamut colors often enough donít come from the scene itself, but are created unintentionally when we work from "linear Raw" to a pleasing rendition.

Peter

--
Title: Color space/bit depth in ACR
Post by: digitaldog on February 28, 2010, 12:48:12 pm
Quote from: DPL
Another question is, if such rigid editing space i.e. 1.0 pRGB ("linear gamma" ProPhoto RGB)
was really a good choice.

Considering that the raw data is a linear encoding, yes. You can take that up with Thomas Knoll however.
Title: Color space/bit depth in ACR
Post by: Schewe on February 28, 2010, 01:56:22 pm
Quote from: DPL
I tend to conclude that the editing space should be limited and change to the gamut primaries of the selected output space, even down to sRGB if needed (while keeping it at "linear gamma" in ACR).


And this based on what research?

Maybe you should apply for a job on the Camera Raw team...so far they have guys from MIT, Carnegie Mellon and the University of Michigan. One of the guys was even smart enough to co-author Photoshop.

You are welcome to question what Thomas Knoll does (and why he does it) but it's really not a fruitful endeavor. Thomas is right more often than just about anybody else I know.

An "editing space" needs to be able to contain both the original capture data as well as any potential output space. That will requires wasting some gamut. So far as I know, that's NEVER caused a problem for Camera Raw (or Lightroom).
Title: Color space/bit depth in ACR
Post by: bjanes on February 28, 2010, 02:07:21 pm
Quote from: DPL
Another question is, if such rigid editing space i.e. 1.0 pRGB ("linear gamma" ProPhoto RGB)
was really a good choice.

I tend to conclude that the editing space should be limited and change to the gamut primaries of the selected output space, even down to sRGB if needed (while keeping it at "linear gamma" in ACR). Thus, avoiding to have too much Oog colors created in the course of image editing.  Out-of-gamut colors often enough donít come from the scene itself, but are created unintentionally when we work from "linear Raw" to a pleasing rendition.
--
Peter's comment is a good one, but ACR allows you to select 1 of 4 output spaces and the preview and histogram are for that space.  If you are rendering into sRGB, saturation clipping can be previewed if your monitor's gamut is sufficiently high and it is shown on the histogram. In Lightroom, clipping can go undetected.
Title: Color space/bit depth in ACR
Post by: Eyeball on February 28, 2010, 02:35:00 pm
If I read Peter's comments correctly, he is referring to "early-binding" of the colorspace as opposed to "late-binding".  It's nice to have a choice as ACR currently provides, albeit in a somewhat limited fashion.  After reading all of the clarifications here, the colorspace in the ACR workflow options is basically a limited form of soft-proofing - something that LR currently doesn't provide and is handy if you are going directly to final image from the raw developer.  Going directly to output from the raw developer is becoming more and more common as the functionality of the developer increases.

On the other hand, it is also nice to have the late-binding alternative and doing everything in 16-bit ProPhoto, so that you can create intermediate images that can be adapted easily to a variety of output media in the future.

I am sure there is tons of expertise on the Adobe team but it is rather interesting that ACR has this pseudo soft-proofing capability built-in and LR doesn't since I suspect it is more common to go direct to output with LR than with ACR.   There probably was some historical baggage involved and maybe we'll see some changes on this in the new versions of PS and LR anyway.
Title: Color space/bit depth in ACR
Post by: nrennie on April 19, 2010, 08:54:35 am
Quote from: Schewe
In terms of the actual editing, no difference at all (other than the fact that Lightroom is a "bit" more usable due to having as many panels open at once as you like).

There is a big difference in terms of being able to FIND my raw files however and after any final Lightroom edits followed by Photoshop edits I keep all my master print files in Lightroom because I greatly prefer to print from Lightroom instead of Photoshop.

I don't have any problems however, using either Lightroom or ACR/Bridge...it all depends on what I'm doing at the moment. If all I want to do is open a raw image and look at it, I would prolly simply point Bridge to the folder it's in and use Camera Raw...

What I don't do much of however is try to alternate back and forth between Camera Raw and Lightroom for edits...it can be done as long as you remember to save out the .xmp from Lightroom after an edit and then read the .xmp from the file after a Camera Raw edit...but that quickly becomes a problem keeping track of the last edit.

Since I have to teach much more with ACR, I am more used to its workflow than LR, But like you, I always ingest into LR since it creates that database which is so useful.  However, my parallel need for LR comes in the form of a non-disappearing history for the parametric editing.  Am I missing something in ACR?
Neil
Title: Color space/bit depth in ACR
Post by: madmanchan on April 19, 2010, 09:15:10 am
Hi folks, the internal reference scene-referred space in Camera Raw & LR is indeed RIMM (ProPhoto linear). However, that does not mean that all internal image processing operations are performed directly in that space. The actual color space used for an operation depends on the routine (e.g., noise reduction, clarity, fill light, HSL adjustments, etc.). The important thing is that the entire process is color-managed so that we can always get to & from the reference space. All of this is done automatically, starting from the source raw image data.