LUT vs Curves Profile

[eladrin SourceForge]

Hello, I recently found out that photos look a bit different in Lightroom CC and Photoshop CC with a LUT profile. More specifically the blacks are a bit more clipped in Photoshop (other than that, the same), even in Adobe Camera Raw within Photoshop. I pinpointed the cause to the XYZ LUT + matrix profile I am using. Is that an expected behaviour?

I then created a Curves + matrix profile from the measurement data and now the photos look exactly the same in both programs. I also don’t see any difference in photos between the XYZ LUT and Curves profiles. Does LUT have any advantage over Curves? Is using a Curves profile the solution to my problem or something is messed up with my Photoshop and Lightroom? Thanks.

[Florian Höch]

Hi,

I recently found out that photos look a bit different in Lightroom CC and Photoshop CC with a LUT profile. More specifically the blacks are a bit more clipped in Photoshop

Without more specifics I’m unable to comment. Adobe’s color engine (ACE) is usually very consistent between products.

Does LUT have any advantage over Curves?

Yes, LUT profiles are more accurate (in some cases significantly so). How much more accurate depends on how nonlinear the screen is, I’ve seen anywhere from roughly 1 to 5 deltaE76 average.

[eladrin SourceForge]

Hi, the specifics of my machine are :

-Windows 8.1 64-bit Lenovo W530 Laptop
-Internal Panel http://www.panelook.com/B156HW01%20V4_AUO_15.6_LCM_overview_686.html
-ColorMunki Display for calibration
-Adobe Photoshop CC 2015.0.0 Release with Adobe Camera Raw 9.1.1.461
-Lightroom CC 2015.1 with Adobe Camera Raw 9.1
-Working Space is ProPhoto RGB in Photoshop and Develop module is used in Lightroom (which I think uses ProPhotoRGB aswell)

I’ve attached the LUT profile, measurement reports of the LUT and Curves profiles and some screenshots of a dark area of an image in Lightroom, Photoshop and XnViewMP (I can provide a better comparison image, this is just a random image off the web zoomed to 200%). Photoshop clearly looks like is clipping the shadows a bit.

If you need any more info, let me know. Thanks.

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[Florian Höch]

Thanks. Your woes are coming from using black point compensation for a LUT profile, which reduces its accuracy near black. Fortunately, this is easy to fix (no need to take new measurements):

1. Go to the “Profiling” tab.
2. Disable black point compensation.
3. In the “Options” menu, select “Create profile from measurement data…”, select the existing profile, and save it.
4. After processing is finished, install the profile.

[eladrin SourceForge]

Thank you!! That was it.

[Author]

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