Auto Brightness

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Auto Brightness is a Windows desktop utility for controlling monitor brightness and contrast from a compact PyQt6 tray app. It supports DDC/CI external displays through native Windows DXVA2 APIs, WMI brightness fallback for compatible built-in displays, global hotkeys, content-aware automatic brightness, and LAN-based remote monitor control.

Features

• Adjust brightness and contrast for supported local monitors.
• Link all monitor brightness values with one global slider.
• Automatically adjust backlight brightness based on screen content luminance.
• Configure global mouse-wheel and keyboard shortcuts.
• Keep monitor settings available even when a display is temporarily disconnected.
• Re-detect hot-plugged displays without restarting the app.
• Run from the Windows system tray with a live brightness icon.
• Optional DDC over LAN mode using TCP and mDNS discovery.
• Optional DXGI capture acceleration through dxcam and numpy.

Requirements

• Windows.
• Python 3.10 or newer is recommended.
• Monitors that support DDC/CI for external brightness and contrast control.
• Python packages: PyQt6, zeroconf, numpy, dxcam, wmi.

Installation

git clone https://github.com/XPRAMT/Auto-Brightness.git
cd Auto-Brightness
python -m venv .venv
.\venv\Scripts\Activate.ps1
python -m pip install --upgrade pip
python -m pip install PyQt6 zeroconf numpy dxcam wmi

All listed packages are imported at startup. If one is missing, the app exits immediately so the missing dependency can be installed before use.

Usage

python .\brightness.pyw

The app starts as a tray application. Open the tray menu to show the main settings window, configure monitor ranges, tune automatic brightness, set shortcuts, or enable network mode.

Settings are saved in settings.json next to the application file. The file stores monitor ranges, global link value, shortcut configuration, automatic brightness settings, startup preference, and network mode.

Network Mode

Network mode allows one machine to expose its local DDC/WMI monitors and another machine to control them over the LAN.

• Server mode listens on TCP port 9876 and advertises _brightnessddc._tcp.local. through mDNS.
• Client mode discovers servers with Zeroconf and displays remote monitors in the same UI.
• The protocol is JSON line based and supports listing monitors and setting brightness or contrast.

Enable either Server or Client from the app's Network tab. Make sure Windows Firewall allows the app or Python process to communicate on the local network.

Automatic Brightness

Automatic brightness samples screen luminance and gradually adjusts monitor backlight toward the configured target. You can tune the target brightness, threshold, weight, capture interval, step percentage, and resource-saving idle behavior in the settings UI.

The app uses dxcam and numpy for DXGI screen capture.

Notes

• DDC/CI must be enabled in the monitor OSD menu for most external displays.
• Some monitors or adapters do not expose brightness or contrast controls through DDC.
• WMI brightness fallback depends on Windows and display hardware support.
• If a display is missing at startup, use the refresh button to re-detect monitors after it becomes available.