Mac OS colosync may be broken.

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  • Updated 7 days ago

This question/comment is regarding Mac OS colorsync mistmatch with PS/LR rendering.


Problem: Despite proper calibration and ICC profiles, rendering of shadows in quicklook/preview differs from PS/LR. My inclination is to trust PS/LR rendering, as the OS (I'm assuming Metal api) rendering of the same image (grey patch ramp from 1-40) crushes the blacks in the first row. Could have future implications for PS/LR if Metal rendering is further integrated.

 

Testing conditions: Mac OS 10.14.5/6
2018 Mac mini, 2015 Macbook Pro 13"
Latest versions of each app.

Monitor calibrated with i1Display Pro to sRGB target colorspace, gamma 2.2, 120 cd/m2, native contrast

Proper monitor profile selected in system preferences.

Same image (located at www.lagom.nl) loaded in PS and Preview.
Issue can be replicated on both machines reliably.

Comments: This issue has been driving me insane, though the effect is obviously more subtle in real-world examples of images (photography). From what I can find online, it appears to be a longstanding issue at the OS level by Apple. For whatever reason, applying different gamma/blackpoint is suspected. Most visible in near black tones as demonstrated above. I've been in contact with NEC's director of software development for a number of problems relating to this.

Additionally, GPU rendering in LR is also subtly different than off for the same image. Not as severe as the above example, but noticeable when knowing what to look for.

It's likely an OS issue, which is very disappointing. I'm hoping Adobe can work with Apple to get to the root of this problem.

Any insights would be greatly appreciated. If you can replicate the issue on your own machines, please do chime in. It'll help develop a case.

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Steven Chung

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Posted 1 week ago

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Andrew Rodney

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It's a bug, it affects Preview, Photoshop and LR (app's using ACE) are fine (they are correct). Apple knows about this. 
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Steven Chung

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Thank you for letting me know. I've been talking with a number of people that support that idea. Unofficial release notes for MacOS do mention changes to ColorSync. The difference is actually much worse in 10.14.6 (I've reverted to 10.14.5 for now), which is what tipped me off to the change. I'm just surprised something like this would slip through. We've fortunately found a valid workaround for the issue, which involves using a point curve for gamma in the ICC profile, instead of a parametric function that requires interpolation of intermediate values by ColorSync.
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Andrew Rodney

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The 'we' might be the same people, who after asking me to do some testing, told me it's an Apple bug and Apple knows about this..... People I know that do know. I haven't spoken with Apple so I don't want you to believe they absolutely know about this bug. But I can say my testing didn't show any abnormalities with Photoshop. 
(Edited)
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Steven Chung

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I've come to the same conclusion with Adobe apps. In my case, I've been in contact with NEC's software dev team (Spectraview). Hoping it'll be resolved soon.
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SaltLife561

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I see it too and it's very frustrating, especially when previewing raw files from the memory card, before importing into LR, for quick culling. I've also noticed when using the quick view on Mac (space bar) it first does not crush the blacks, but if playing a slideshow or opening the same image in Preview, then it crushes the blacks and after that opening it in quick view also crushes the blacks. I've learned to just ignore it (color) and check focus only.

Anyone know if same problem exists in Photo Mechanic?