colours are not right on iMac 2020

[ThomasWaldmann]

input-dockstation branch

I have the same wallpaper on the iMac 2017 (macOS 13.7.8) and the iMac 2020 (macOS 26.5).

Same 5K@48 stream params, both extended desktop, both audio.

On the iMac 2017, the wallpaper looks good, colours are smooth.

On the iMac 2020, the wallpaper looks worse:

• blacks not deep
• i see steps in the gradient of gray to black

[ThomasWaldmann]

The framebuffer contents seem to be identical:

If I screenshot the bad wallpaper and preview it, looks bad also on the iMac 2020.

When I move the preview window to the iMac 2017, it looks good.

[ThomasWaldmann]

Note: Rebooting the 2020 iMac did NOT help.

[swellweb]

I think it's an issue of refresh buffer.

[ThomasWaldmann]

I tried fixing it, but did not find a solution.

If you can find one, that would be nice to have in next release.

Will have to check whether this is actually a regression from past releases.