P: Photoshop 27.8 & later Rendering Artifacts, Exposed Previews and Color Banding

Doing some research, apparently this is a known bug that will be patched soon. The fix for now is to go into Settings:Technology Previews and to turn on “Precise color management for HDR display”, then quit and restart. (I tried this and it does fix the issue)

This is using a fairly new Mac M5 Max laptop with Lightroom Classic and Photoshop installed. Everything was “normal” as of a month ago (I normally work on images in Classic, then Edit in Photoshop to print, and I’d done some prints on this system, with the latest Tahoe and Adobe software, at that point).

This week, I went to make more prints, and now: Edit in Photoshop, from Classic, is “broken”: the image in Photoshop is lighter and desaturated. No way around this from the Lightroom side: any attempt at changing settings; or bypassing the direct Edit In step by saving to a JPG or TIFF; produces the same results. (I’m a color management expert, this isn’t “user error” by a novice).

Next step was to try on a different system. I have a Mac M4 Max laptop that’s running the latest version of Sequoia - not updated to Tahoe - with the same current version of Photoshop and Lightroom Classic installed. Moved my external drive (images and catalog) to that system, tried it: everything works fine, the color is correct. Implication is, the problem is the latest Tahoe release. (I have Golden Gate developer beta on yet another Mac laptop but haven’t tried it there yet). But anyway:

I went back to the M5 Max, played with Color Settings some more, then decided to try something obvious. I switched the rendering engine from Adobe Color Engine (ACE) to the Apple CMM. And doing that fixes it. Now the color is fine.

So the problem ends up being: Adobe Color Engine is broken and/or unavailable on the M5 Max with Tahoe 26.2. Doesn’t -seem- to be inherent in the Photoshop 27.9.0 build itself since “that build works on the M4 Max Sequoia system”. So my question (also as a developer) is: is ACE supposed to be built into MacOS, independently of Adobe software, and did it go “missing” in the latest Tahoe release? That would be one explanation. Or, is it installed as part of the Photoshop installation, and is it somehow “not installed” on my M5 Max with Tahoe 26.2, but yet it’s “still installed” on the M4 Max with Sequoia, where it’s functional?

I can work around this simply by switching to the Apple CMM for now. I’d prefer to get back to Adobe ACE for this workflow “just because”, even though I don’t expect the color processing pipeline to produce visibly different results that way.

Someone should look into this; I’m surprised that I’m not seeing any other reports. (Unless this is potentially a problem with my Photoshop install; in which case, should I remove it and reinstall it?)

I updated to the latest version and the result is the same. This problem only occurs when converting RGB to CMYK. Creating gradients and painting is fine.
I had to install an older version of PS to do that, as I had some basic errors ;)

Title

Photoshop 27.9.1 (Apple Silicon): 16-bit Gray Gamma 2.2 documents display severe posterization with GPU enabled; TIFF data and prints are correct

System

Photoshop 27.9.1
macOS Tahoe 26.6.1
Mac Studio M2
Eizo 10-bit display
GPU enabled

Steps to reproduce

Create a new 16-bit Adobe RGB (1998) document.
Draw a smooth black-to-white gradient.
Convert to Gray Gamma 2.2 (or Image → Mode → Grayscale).
Observe severe tonal stepping in Photoshop.

Expected

The gradient should remain perfectly smooth.

Observed

The Convert to Profile preview is smooth.
After the conversion is committed, Photoshop displays strong posterization.
A screenshot captures the posterization.
Saving the 16-bit TIFF and opening it in macOS Preview shows a perfectly smooth gradient.
Printing the TIFF with PrintTool/QuadTone RIP produces a perfectly smooth print.
Converting the grayscale TIFF back to Adobe RGB in Photoshop also displays smoothly.
Disabling Use Graphics Processor completely eliminates the posterization.

Conclusion

This appears to be a GPU/Metal rendering issue affecting Photoshop's display of 16-bit grayscale documents. The underlying image data are correct.

Photoshop Beta – GPU ON causes incorrect color/saturation compared with Camera Raw and GPU OFF

Bug description

Şunu olduğu gibi kopyalayıp Adobe Community'deki Leave a reply alanına yapıştırabilirsin:

I have identified a reproducible color rendering issue in Photoshop Beta when the Graphics Processor is enabled.

The same image is displayed correctly in Camera Raw and in Photoshop Beta when Use Graphics Processor is disabled.

However, when Use Graphics Processor is enabled, the image appears noticeably different, particularly in terms of color saturation and color rendering.

I have tested this several times with different images and obtained the same result:

Camera Raw → correct colors
Photoshop Beta + GPU OFF → correct colors
Photoshop Beta + GPU ON → incorrect/different colors and saturation

The difference disappears when I disable Use Graphics Processor and restart Photoshop.

This makes me believe the issue is related to GPU-based rendering/color management rather than the image file itself or the Camera Raw settings.

Photoshop Beta version: 27.11.0
Operating system: Windows 11
Computer: ASUS Vivobook Pro 16X OLED

I can provide screenshots showing the same image side-by-side with GPU enabled and disabled if needed.

Please investigate the GPU color rendering/color management behavior in the current Photoshop Beta.

Ok, I'll check,

Known bug. IIRC there’s a fix in the latest beta, but can’t recall if it has made it to the production version yet. But it will.

It was the same in the previous version: when converting an RGB photo to CMYK, banding appears in gradient areas. The same photo converts perfectly in Photoshop version 27.5.

Orginal

PS 27.9  Convert to CMYK  - problem gradient

PS 27.5 Convert to CMYK  - gradient Ok

An update on the two bugs mentioned in this thread:

• Washed-out colors: The fix is included in the latest Photoshop release, PS 27.9.1.
• Banding during RGB → CMYK conversion: The fix is available in the latest Photoshop Beta build 27.11.

Ah, c’était bien la mise à jour Photoshop qui a créé ce bug! J’ai réinstallé l’ancienne version, le problème a disparu!!