P: Photoshop 26.10 Incorrect alpha blending on canvas for gamma 1.00 at different zoom levels

[welk171]

Issue: 

• Photoshop version: 26.10.0 20250811.r.7 x64 (final, Release)
• OS: Windows 11 64-bit (10.0.26100.4946), 4070 RTX (mobile), i7-13700h, Windows HDR enabled

Steps to reproduce:

1. Create a new 1000 x 1000 px document., RGB, 8 bit.
2. In [Edit > Color Settings...] enable "Blend RGB colors using gamma 1.00".
3. Enable [Settings > Technology Previews > Precise color management for HDR display], but
   it seems to be irrelevant (that's the only other setting I changed since Photoshop installation).
4. Create 200 x 200 px, #00f blue raster square with 50% opacity ("Normal" blend).
5. Ctrl + J to duplicate this layer.
6. Group them.
7. Fill bg to say #eee.
8. Notice that the color they have is #6767f8 (correct I assume).
9. Move the group with the Move Tool (V) and notice the color changed to #7f7ffb.
10. Use zoom/pan (Z) and notice it flickered back to #6767f8.
11. It's even possible to duplicate this group and fix both copies by the zoom tool
    and then drag only one of these groups with Move Tool (V) and screenshot this
    and clearly see the bug being screenshottable only on the group that was just dragged.
    
    
    

Expected result: 
Blending works consistently and produces always only #6767f8 blend.

Actual result:
Wrong blending only when gamma is 1.00.
It works with default settings for [Edit > Color Settings...].

[creative explorer]

@welk171 learn something new! I guess I really didn't notice this on a MAC?

[welk171]

It was supposed to be a bug report but someone from Adobe moved it to "Discussions".

I think this is clearly a bug because simply using Move (V) and Zoom (Z) tools changes the canvas preview and at random alternates between correct and incorrect colors.

There is no response or interest from Adobe though but on Windows it's impossible to work in Gamma = 1.00 mode.

[welk171]

Same here in 2025, this is still not fixed, using Move (V) and Zoom (Z) tools changes the colors of my layers in gamma = 1.00 mode.

Legacy compositing is now gone and can't be enabled.

Photoshop version: 26.10.0 20250811.r.7 x64 (final, Release)
OS: Windows 11 64-bit (10.0.26100.4946), 4070 RTX (mobile), i7-13700h, Windows HDR enabled

[Sameer K]

Hey, @welk171. Thanks for the detailed post. Although I don't have an HDR-certified primary display, one of my secondary screens was recently calibrated and HDR-certified. 

I've tried to recreate this with the detailed steps, and Photoshop behaved as expected (No color shifts). Could you include a video of the steps and your precise workflow? 

Awaiting to hear from you. Thanks!

Sameer K
(Type '@' and type my name to mention me when you reply)

[welk171]

I'm attaching a video @Sameer K 
I don't think the display makes any difference but HDR and gamma = 1.00 workflows will be gaining popularity for sure.

[Srishti Bali]

Hi @welk171

Sorry to hear you’re running into this issue, and thank you for sharing details about your setup. Could you please share a short video showing the error, along with a sample file if possible? Also, can you confirm whether this happens with all files or only specific ones?

This information will help us reproduce the issue on our end and share the details with the Product team.

Regards,

Srishti

[welk171]

Thanks, the video is here: https://community.adobe.com/t5/photoshop-ecosystem-discussions/wrong-alpha-blending-for-gamma-1-00/m...

It happens with all files.

[Sameer K]

Thanks for providing the video. I've shared it with the team internally for an early review. 

Best,
Sameer K
(Type '@' and type my name to mention me when you reply)

[Sameer K]

Thanks for sharing the video. The team has investigated this, and we can reproduce this. 

For now, could you try disabling GPU compositing? Here's how you can do it:

1 - Go to Photoshop in the top menu > Preferences, then Performance.
2 - Click on Advanced Settings.
3 - Uncheck the GPU Compositing option.

After doing this, restart Photoshop and see if the issue exists. If it doesn't help:

1 - Go to Photoshop in the top menu > Preferences, then Performance.
2 - Disable GPU usage altogether and check how it goes. 

Thanks!
Sameer K
(Type '@' and type my name to mention me when you reply)