Gamma Control (gammactrl)

A graphical utility to adjust display gamma on KDE Plasma Wayland sessions.

Wayland does not natively support legacy X11 gamma adjustment tools like xgamma. This tool works around that limitation by copying your active ICC color profile (or generating a neutral one), patching the VCGT (Video Card Gamma Table) tag with your desired gamma multiplier, and applying it seamlessly using kscreen-doctor.

Note: HDR is not supported yet.

Prerequisites

To build and run this application, you will need the following packages installed on your system. The exact package names may vary slightly depending on your Linux distribution.

Build Dependencies

• A C compiler (gcc or clang)
• cmake
• pkg-config
• GTK4 development headers (e.g., libgtk-4-dev on Debian/Ubuntu, or gtk4-devel on Arch/Fedora)

Runtime Dependencies

• kscreen-doctor (typically included with KDE Plasma via the libkscreen package)

Building and Installing

1. Make the scripts executable:

   chmod +x build.sh install.sh

2. Build

   ./build.sh

3. Build and install:

   ./install.sh

Alternatively, you can run the CMake commands manually:

cmake -B build
cmake --build build
cmake --install build --prefix ~/.local

Usage

After installation, launch gammactrl in your terminal or search for "Gamma Control" in your application launcher.

Use the slider to dynamically brighten or darken your display.

The application uses a default baseline. This should be fine unless the baseline does not align with your actual screen default gamma. To set a custom baseline for a monitor, use the Resync Baseline button.