A lightweight red screen filter for Windows that reduces eye strain
simple, no overlays, no gimmicks.
RF-DEX applies a system-wide red colour filter to all your monitors using the Windows Magnification API (MagSetFullscreenColorEffect).
The effect is applied at the DWM compositor level — the same mechanism Windows itself uses for colour filters in Accessibility settings — so it works across all applications, including fullscreen games and system dialogs.
Download the latest release from the Releases page. Three options are available:
| File | Description |
|---|---|
RF-DEX-x.x.x-portable.exe |
Single file, no install required. Just run it. |
RF-DEX-x.x.x-setup.exe |
Inno Setup installer with optional startup entry |
RF-DEX-x.x.x.msi |
MSI installer for managed/enterprise environments |
The portable exe requires no installation and supports all features.
Once running, RF-DEX lives in the system tray (bottom-right notification area). Right-click the tray icon to access the menu.
| Action | How |
|---|---|
| Change strength | Right-click → drag the slider (0 %–100 %) |
| Toggle on / off | Right-click → Toggle On / Off |
| Start with Windows | Right-click → check Start with Windows |
| Exit | Right-click → Exit |
Settings (strength and active state) are saved automatically and restored on next launch. The filter is removed when the app exits.
- Windows 10 / 11
- .NET 9.0 SDK or later
git clone https://github.com/MyDrift-user/RF-Dex.git
cd RF-Dex
dotnet run --project src/RF-DEX.\scripts\build.ps1Produces artifacts/RF-DEX-x.x.x-portable.exe, RF-DEX-x.x.x-setup.exe, and RF-DEX-x.x.x.msi. Requires Inno Setup and WiX Toolset for the installer targets.
RF-Dex/
├── assets/ # Logo and branding assets
├── installer/
│ ├── installer.wxs # WiX MSI installer
│ └── setup.iss # Inno Setup installer
├── scripts/
│ └── build.ps1 # Local build script
├── src/
│ └── RF-DEX/
│ ├── Core/
│ │ ├── MagnificationApi.cs # P/Invoke bindings for Magnification API
│ │ └── ScreenFilter.cs # Filter logic and strength control
│ ├── Settings/
│ │ └── AppSettings.cs # Settings persistence & startup registration
│ ├── UI/
│ │ ├── TrayIcon.cs # System tray integration
│ │ └── TrayMenu.cs # Context menu
│ ├── Program.cs
│ └── RF-DEX.csproj
├── LICENSE
└── README.md
RF-DEX calls MagSetFullscreenColorEffect with a 5×5 colour-transform matrix that scales the green and blue channels down while leaving red at full:
| 1.0 0 0 0 0 |
| 0 keep 0 0 0 |
| 0 0 keep 0 0 |
| 0 0 0 1 0 |
| 0 0 0 0 1 |
Where keep = 1.0 - (strength / 100.0). At 30 % strength, green and blue are at 70 % of normal. At 100 %, only the red channel remains.
This project is licensed under the MIT License — see LICENSE for details.
Made with ❤️ by MyDrift