Bug 495248 - Show info whether the backlight of the screen is changed or it's just a visual software effect
Summary: Show info whether the backlight of the screen is changed or it's just a visua...
Status: RESOLVED INTENTIONAL
Alias: None
Product: plasmashell
Classification: Plasma
Component: Power management & brightness (other bugs)
Version First Reported In: 6.2.4
Platform: Other Linux
: NOR wishlist
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2024-10-23 15:41 UTC by postix
Modified: 2025-08-20 13:58 UTC (History)
3 users (show)

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Description postix 2024-10-23 15:41:07 UTC
SUMMARY

In the applet I can change my screen's brightness, but it seems the backlight isn't changed actually, but a rather a software overlay is used. 

It'd be great if this were communicated to the user, so that one doesn't just dim it in software only in the end and forgets about the actual backlight.

SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20241021
KDE Plasma Version: 6.2.1
KDE Frameworks Version: 6.7.0
Qt Version: 6.8.0
Kernel Version: 6.11.3-2-default (64-bit)
Graphics Platform: Wayland
Graphics Processor: AMD Radeon RX 580 Series
Comment 1 Nate Graham 2025-06-04 19:52:26 UTC
Can you mention why this matters? What's the problem with the software brightness being used, and why is it important to know the actual backlight level?
Comment 2 postix 2025-06-04 20:49:22 UTC
> What's the problem with the software brightness being used, and why is it important to know the actual backlight level?

I can change the brightness now in two ways and that's indeed pretty nice: 
a) directly adjust the panel background lightning via a menu of the desktop monitor (in a range of 40 cd/m^2 up to 350 cd/m^2)
b) in software by the kde applet :-)

When I opened this issue, it was not directly clear to me if the applet influences a) or b), since in principal you can also adjust the monitor's brightness directly via DDC if supported.

That means to save energy, a) is the way to go. To get minimal or maximal brightness a) and b) should be considered.

Or am I mistaken and the applet always only controls the brightness by an overlay and never by adjusting the panel's backlight?
Comment 3 postix 2025-06-04 21:04:27 UTC
> Or am I mistaken and the applet always only controls the brightness by an overlay and never by adjusting the panel's backlight?
Actually I'm not, on the laptop the backlight is directly adjusted by the applet, I cannot lower the brightness further as it doesn't offer an additional software overlay.

Maybe a twofold slider would work in those cases: [ additional software darkening |  screen backlight ], similar to "raise maximum volume" for audio. 

Anyway, that would be something for another issue, but should hopefully give some more background information on the reasoning for this one.
Comment 4 Nate Graham 2025-06-06 17:08:45 UTC
The applet controls the backlight if the hardware allows software control of it. If not, it uses a darkened overlay. So only one method is ever in use.

Unsure if this is worth doing.
Comment 5 Nate Graham 2025-08-19 21:16:27 UTC
Gonna be bold and say this isn't worth doing, sorry.
Comment 6 postix 2025-08-20 10:16:43 UTC
(In reply to Nate Graham from comment #5)
> Gonna be bold and say this isn't worth doing, sorry.

No worries ;) I do development myself and I know you can't grant every wish. Thanks for your great work everyday anyway! :)
Comment 7 Nate Graham 2025-08-20 13:58:39 UTC
You're welcome!