[GH-ISSUE #1376] Change Backlight instead of Luminance on LCD screens? #783

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opened 2026-05-05 06:41:50 -06:00 by gitea-mirror · 1 comment

gitea-mirror commented

2026-05-05 06:41:50 -06:00

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Originally created by @torik42 on GitHub (May 24, 2023).
Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1376

Before opening the issue, have you...?

Searched for existing issues
Read through the Monitor-Troubleshooting Wiki
Updated MonitorControl to the latest version (if applicable)

Describe the issue

Thank you for the great App, it is (would be) much nicer to control a monitor via the OS than with the OSD.

My problem is, that changing the Brightness on a Fujitsu B27‑8 TS Pro does change what is called “Black level” in the OSD. Changing the contrast works as expected. Instead, I would like to change what is called “Brightness” in the OSD. I guess, it controls the backlight, which should also be accessible via DDC. The reason seems to be that MonitorControl changes “Luminance”:
03355a0fa9/MonitorControl/Enums/Command.swift (L171)
Instead of what I guess is the backlight control:
03355a0fa9/MonitorControl/Enums/Command.swift (L110)

I found this source explaining the three terms mainly for old CRT displays, but also mentioning LCD screens. The same issue exists when using other tools like ddcctl. And I haven’t found a way to test as I have not yet found a tool for mac, which easily lets me send other commands. That might even be a bad idea because some people have bricked their monitors by sending unsupported controls (ddcctl issue). I also haven’t found a tool for mac, that allows to easily ask for the capabilities of the monitor (ddcctl feature request).

I am not sure, whether also other users have this problem, or whether some monitors actually implement luminance as backlight luminance (see above’s source again). Then it would be great to have a switch between these options, or even a third control.

For now, I have the following questions:

Do you know a tool for macOS which lets me query the capabilities and send custom commands? (This fork of ddcctl has the ability to send, but not query the monitor to my understanding)
There is a VCP list in the advanced settings section for which I could not find any documentation. Does it allow sending custom commands?
If 2 is the case, does MonitorControl ask the monitor for supported commands and only send those?

Expected behavior

MonitorControl to set the Monitors Brightness (probably backlight luminance) instead of black level.

Anything else?

see above

Environment Information (please complete the following information)

- macOS version: 13.2.1 Ventura
- Mac model: MacBook Pro (16 inch, 2019)
- MonitorControl version: 4.1.0 Build 7034
- Monitor(s): Fujitsu B27‑8 TS Pro
- Monitor Cable(s)/Connection(s): USB‑C to DP cable
- Apple Silicon/M1 (yes or no): no

Originally created by @torik42 on GitHub (May 24, 2023). Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1376 ### Before opening the issue, have you...? - [X] Searched for existing issues - [X] Read through [the Monitor-Troubleshooting Wiki](https://github.com/MonitorControl/MonitorControl/wiki/Monitor-Troubleshooting) - [X] Updated MonitorControl to the latest version (if applicable) ### Describe the issue Thank you for the great App, it is (would be) much nicer to control a monitor via the OS than with the OSD. My problem is, that changing the Brightness on a Fujitsu B27‑8 TS Pro does change what is called “Black level” in the OSD. Changing the contrast works as expected. Instead, I would like to change what is called “Brightness” in the OSD. I guess, it controls the backlight, which should also be accessible via DDC. The reason seems to be that MonitorControl changes “Luminance”: https://github.com/MonitorControl/MonitorControl/blob/03355a0fa9f94d5789b7b266c4ef8dc1bcdbca53/MonitorControl/Enums/Command.swift#L171 Instead of what I guess is the backlight control: https://github.com/MonitorControl/MonitorControl/blob/03355a0fa9f94d5789b7b266c4ef8dc1bcdbca53/MonitorControl/Enums/Command.swift#L110 I found [this source](https://www.poynton.ca/notes/brightness_and_contrast/index.html) explaining the three terms mainly for old CRT displays, but also mentioning LCD screens. The same issue exists when using other tools like ddcctl. And I haven’t found a way to test as I have not yet found a tool for mac, which easily lets me send other commands. That might even be a bad idea because some people have bricked their monitors by sending unsupported controls ([ddcctl issue](https://github.com/kfix/ddcctl/issues/89)). I also haven’t found a tool for mac, that allows to easily ask for the capabilities of the monitor ([ddcctl feature request](https://github.com/kfix/ddcctl/issues/58)). I am not sure, whether also other users have this problem, or whether some monitors actually implement luminance as backlight luminance (see [above’s source again](https://www.poynton.ca/notes/brightness_and_contrast/index.html)). Then it would be great to have a switch between these options, or even a third control. For now, I have the following questions: 1. Do you know a tool for macOS which lets me query the capabilities and send custom commands? ([This](https://github.com/itxch/ddcctl) fork of ddcctl has the ability to send, but not query the monitor to my understanding) 2. There is a VCP list in the advanced settings section for which I could not find any documentation. Does it allow sending custom commands? 3. If 2 is the case, does MonitorControl ask the monitor for supported commands and only send those? ### Expected behavior MonitorControl to set the Monitors Brightness (probably backlight luminance) instead of black level. ### Anything else? see above ### Environment Information (please complete the following information) ```markdown - macOS version: 13.2.1 Ventura - Mac model: MacBook Pro (16 inch, 2019) - MonitorControl version: 4.1.0 Build 7034 - Monitor(s): Fujitsu B27‑8 TS Pro - Monitor Cable(s)/Connection(s): USB‑C to DP cable - Apple Silicon/M1 (yes or no): no ```

gitea-mirror closed this issue

2026-05-05 06:41:52 -06:00

gitea-mirror commented

2026-05-05 06:41:55 -06:00

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@waydabber commented on GitHub (May 31, 2023):

Hi @torik42 - you can use both MonitorControl and BetterDisplay to override the control code for Brightness/Luminance.

In BD, you can do it here:

In MC, you can do it here:

@waydabber commented on GitHub (May 31, 2023): Hi @torik42 - you can use both MonitorControl and [BetterDisplay](https://betterdisplay.pro) to override the control code for Brightness/Luminance. In BD, you can do it here: <img width="942" alt="Screenshot 2023-05-31 at 16 30 28" src="https://github.com/MonitorControl/MonitorControl/assets/37590873/628a1f45-b330-4373-8266-22d6f9215a62"> In MC, you can do it here: <img width="842" alt="Screenshot 2023-05-31 at 16 31 10" src="https://github.com/MonitorControl/MonitorControl/assets/37590873/a8d34ee9-0ca4-4780-b8eb-a432a524440b">