Colour Shift between Lightroom Library and Develop Modules

[Richard Wozniak]

I wonder if you could help me with a conundrum I have been trying to get my head around?

In Lightroom, sometimes a file displayed in the Library module looks different to the same file in the Develop module.

My understanding has until now been that the Library module simply honours the original profile and keeping the file in its original colour space saves the preview as an 8-bit JPEG and displays it via the monitor profile. So say a ProphotoRGB file is saved as an 8-bit AdobeRGB JPEG and is displayed via the monitor profile (say AdobeRGB for wide gamut).

In the Develop module things are handled differently. The original file is passed through the Lightroom internal colour space (ProphotoRGB with a linear gamma rather than 1.8) and then filtered through MelissaRGB (Prophoto with a tweaked sRGB tone curve gamma 2.2) before being displayed via the monitor profile say, AdobeRGB gamma 2.2 for wide gamut.

My understanding has been that these different processing paths through widely differing colour spaces and architectures (and therefore with scope for quantisation errors?)  is what can lead to a colour shift between the two modules.

Also, I understand Lightroom does not rebuild the standard or 1:1 previews in the Library after changing develop settings but I am sure it updates them on the fly as I never see a difference when switching from one to the other.

The other probably more commonly quoted reason in the real world is inaccurate prosumer monitors which have been poorly calibrated - if at all. Garbage in, garbage out.

A friend of mine came across this colour shift and ascribes the phenomenon to something else.

He has a high-end monitor (NEC PA272W) which he claims can display colour beyond AdobeRGB (which it probably can in the reds and magentas probably with trade-offs elsewhere) and it is this which he claims explains the phenomenon.

(I have never seen this phenomenon on my Eizo but then again I have not gone looking for it. I have checked a range of images and can’t find it. Library and Develop previews look the same to me.)

Anyway, as proof, he created a Prophoto JPEG containing 6 colour blocks - red, green, blue, magenta, cyan and yellow. Each block has three colour strips with the most saturated colour that can be contained in ProphotoRGB, AdobeRGB and sRGB respectively - using RED RGB 255,0,0 in each strip.

When displayed in Library the ProphotoRGB and AdobeRGB strips match, with sRGB looking darker and undersaturated.

However, when displayed in the Develop module, there are distinct differences between between all three strips especially in red and magenta but also in green, blue and cyan but virtually none in yellow. While I agree with his findings, I am not sure they explain the problem as very few people use high end, wide gamut monitors - most use cooking quality sRGB screens or at best, prosumer grade devices yet still report seeing such a shift.

I can reproduce these findings on my Eizo CG318-4K but have struggled to explain it to my own satisfaction.

This is what I have come up with:

In the Library module, the ProphotoRGB file is saved as an 8-bit AdobeRGB JPEG and displayed via the wide gamut AdobeRGB monitor profile.

The ProphotoRGB contains more colours than Prophoto allows and so can only display AdobeRGB.

The AdobeRGB contains all the AdobeRGB colours and displays the full gamut correctly.

The sRGB contains too few colours for the AdobeRGB space and so displays truncated colour.

This agrees with what I see on screen.

In the Develop module the preview is live, the file following the route > LR RGB > MelissaRGB > monitor AdobeRGB.

The ProphotoRGB contains more colours than the 'expanded’ AdobeRGB of the monitor and so displays somewhat more than standard AdobeRGB.

The AdobeRGB contains fewer colours than the monitor is capable of displaying and so displays AdobeRGB correctly - but less than the full capability of the monitor.

The sRGB contains fewer colours than AdobeRGB and so displays truncated - but even more so than before given the "Adobe-plus" gamut of the monitor.

1. Is this what is happening?

2. Does this explain the colour shift between modules?

3. It seems to me that this test is as extreme as it gets, it’s relevance in real world imaging is pretty marginal and would in any event be masked by similar but opposite shifts for other colours.

So, bottom line, what causes the occasional colour shift between the Library and Develop modules in Lightroom?

1. Quantisation errors/use of different colour spaces/different preview architecture - however you want to put it.

2. Insufficiently accurate monitors/inadequate calibration and profiling.

3. Use of highly accurate, well calibrated, expanded gamut monitors.

One, two or some of all three?

Yikes.

Please correct any nonsense and please forgive the length of this email.

[JohanElzenga]

Yes, the Library previews are AdobeRGB, the Develop previews are MelissaRGB (a kind of ProPhotoRGB). So if your monitor can display more than Adobe RGB, then you could see a difference between the two previews (providing that the original file contains more saturated colors than AdobeRGB can hold).

[rune flaatenb40175640]

Thank you for these informative questions and answers!

I recently upgraded from a Microsoft Surface Pro 4 to Pro 7, and to my bewilderment on my new Pro 7 colors in the photograph changed (from hazy greenish to vibrant reds) when swithing from Library to Develop Modules. From the screen specs in Windows, it looks like both screens are sRBG. I first tried to turn off an on the graphics accelerator i LR. When it was off colors were permanently in "Library mode".

I then ran a color calibration in Windows (https://www.digitaltrends.com/computing/how-to-calibrate-your-monitor/) and like magic the problem disapeared. Colors on my Pro 7 now resembles that of the Pro 4, and colors are not changing when I switch between Library and Devlop modules (with graphics accelerator turned on). I can't explain why, but I am very happy with the result. 

Best, 

Rune 

[johnrellis]

"I recently upgraded from a Microsoft Surface Pro 4 to Pro 7, and to my bewilderment on my new Pro 7 colors in the photograph changed (from hazy greenish to vibrant reds) when swithing from Library to Develop Modules. ... I then ran a color calibration in Windows (https://www.digitaltrends.com/computing/how-to-calibrate-your-monitor/) and like magic the problem disapeared. Colors on my Pro 7 now resembles that of the Pro 4, and colors are not changing when I switch between Library and Devlop modules (with graphics accelerator turned on). I can't explain why, but I am very happy with the result."

There've been a few recent reports about color issues with Surface Pros, and it seems that they may be shipping with default color profiles assigned to the display that are not compatible with LR (whether it's a problem in LR or with the profiles, who knows). Re-calibrating to create and assign a new profile, or assigning the standard "sRGB IEC61966-2.1" profile seems to fix the issue. According to a previous report, there may be other profiles containing the characters "sRGB", and those may be part of the problem.

[Use the blue reply button under the first post to ensure replies sort properly.]

[josephlavine]

It sounds as though there are a couple of different things occurring.

1. As you mentioned, the Library and Develop modules use different color spaces and gamut curves, so images will display slightly differently. This can be amplified when using monitors that can reproduce very saturated colors as you'll see tones outside the Adobe RGB spectrum.

2. Monitor to monitor there will be differences simply because of how they are calibrated and profiled. I've seen expensive monitors that reproduce inaccurately and low-end ones that do a great job all based on proper calibration and profiling.

Warmly/j