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Author Topic: LR Color Space varies by Module?  (Read 2441 times)

jtmiller

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LR Color Space varies by Module?
« on: May 10, 2010, 07:54:00 pm »

I've received some opinion that LR uses different color spaces in Library, Develop and Print modules for reasons of performance. I was under the opinion that LR always worked in ProPhoto and displayed through appropriate device specific transforms to the printer or monitor.

The claim was made that the Library and Print modules actually display an aRGB jpeg rather than a realtime transformed ProPhoto as I had assumed.

My reason for asking is that if this is true then one should always be in the Develop module when comparing print to screen on multiple print attempts to ensure an apples to apples comparison. Inadvertent use of the Print (seems obvious choice...) or Library (often first module open) may give the wrong comparison.

We often start a print job then leave and come back after closing LR. Failure to go to Develop module to compare print to screen might be giving us the wrong idea of what we were trying to fix.

Is it really necessary to go back to Develop to get to the unvarnished "truth" after being in the Print module?

Doesn't seem right.

tnx
jim
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digitaldog

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LR Color Space varies by Module?
« Reply #1 on: May 10, 2010, 09:02:54 pm »

Depends on the version to some degree and we’re talking thumbnails/previews. The actual processing is always ProPhoto RGB in a linear TRC.
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jtmiller

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LR Color Space varies by Module?
« Reply #2 on: May 10, 2010, 10:19:13 pm »

Quote from: digitaldog
Depends on the version to some degree and we’re talking thumbnails/previews. The actual processing is always ProPhoto RGB in a linear TRC.

We're using 2.7. What are the versioning implications?

I'm not sure what you mean about actual processing. I process to achieve a visual result so the process is what I perceive with my eyes on a color managed display.

If there is a difference between the displayed image among the various modules I'd like to know about it so I make sure I remove that variable from my editing and evaluation process. Since editing is done in the Develop module it seems as evaluating a print should be done in that module rather than the Print module. But the Print module is the one displaying the image during printing and would be the one used for evaluation if I didn't know that the Develop module is actually "truth."

Is this explained anywhere in the LR documentation?

tnx
jim
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HickersonJasonC

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LR Color Space varies by Module?
« Reply #3 on: May 10, 2010, 11:00:15 pm »

Quote from: jtmiller
Since editing is done in the Develop module it seems as evaluating a print should be done in that module rather than the Print module. But the Print module is the one displaying the image during printing and would be the one used for evaluation if I didn't know that the Develop module is actually "truth."

tnx
jim

I believe that the only way to see exactly what LR is going to do upon export to view at 100%, which is obviously not the ideal for printing. On the other hand, iff you are printing out of LR without soft-proofing through PS, how are you getting accurate prints anyway?
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dgberg

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LR Color Space varies by Module?
« Reply #4 on: May 11, 2010, 05:49:33 am »

My say on this would be once you are in the print module you are done evaluating anything from a photo editing view.  Develop module for evaluation and editing. The print module screen in my eyes is only for a final check on your print layout and borders, nothing else.
« Last Edit: May 11, 2010, 05:51:53 am by Dan Berg »
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digitaldog

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LR Color Space varies by Module?
« Reply #5 on: May 11, 2010, 08:47:55 am »

Quote from: jtmiller
We're using 2.7. What are the versioning implications?

The implications are that in 3.0, things change in terms of the color space (everything is Adobe RGB (1998)) for previews in modules other than Develop as far as I understand it. In 2.X, depending on the quality you set for previews, you might get ProPhoto. Doesn’t matter much unless you use draft printing in terms of what comes out of LR. Otherwise its just used for previewing the images to screen. The underlying raw processing in 2 and 3 fixed at ProPhoto RGB linear TRC (gamma 1.0). That’s what is used to get a rendered image out of LR.

Quote
I'm not sure what you mean about actual processing. I process to achieve a visual result so the process is what I perceive with my eyes on a color managed display.

One mechanism is for previewing your images in various modules. As I said, that is kind of changing and can depend on the preferences you set. It has zero effect on your output. Then there is the processing color space, again its fixed as ProPhoto 1.0 TRC.

Quote
If there is a difference between the displayed image among the various modules I'd like to know about it so I make sure I remove that variable from my editing and evaluation process. Since editing is done in the Develop module it seems as evaluating a print should be done in that module rather than the Print module. But the Print module is the one displaying the image during printing and would be the one used for evaluation if I didn't know that the Develop module is actually "truth."

The modules other than Develop use one kind of preview. They use the previews you build and live in the Irdata file that you’ll see grow as you add images or update a library for larger previews. Develop uses a cache found in the ACR cache which is akin to a raw file. For important decisions and the most exacting preview, you should be viewing images 1:1 in Develop. That’s where you’d make critical decisions anyway right?
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