Screen Dimmer

A tiny, dependency-free screen dimmer for Windows 10/11.

It darkens the display below the hardware minimum and shifts its colour temperature towards warm — the two things the built-in brightness slider cannot do. Useful at night, in a dark room, or when you want a warm, low-blue-light screen.

Why another dimmer?

	Windows brightness slider	Screen Dimmer
Minimum brightness	hardware floor	almost black (95 %)
Colour temperature	fixed	6500 K → 2700 K (warm)
Click-through overlay	—	yes, nothing is blocked
Footprint	—	~30 MB RAM, no installer, no admin rights

Features

• Dim 0–95 % on top of the hardware brightness.
• Warmth 6500 K (neutral) → 2700 K (warm), like a night-light for the screen.
• Screen off — turns the monitor off while the session keeps running (any key or mouse move brings it back).
• Global hotkeys, works while the panel is hidden.
• Tray icon, remembers your settings and the panel position.
• Start with Windows (optional, one click in the tray menu).
• Multi-monitor aware, DPI aware, single instance.

Quick start

1. Download ScreenDimmer.exe from the Releases page.
2. Run it. The panel appears in the bottom-right corner.
3. Drag the sliders, or use the hotkeys.

Nothing to install: it targets .NET Framework 4.x, which ships with Windows. No admin rights, no background services, no network access.

Hotkeys

Shortcut	Action
Ctrl+Alt+↓ / Ctrl+Alt+↑	dimmer / brighter (5 % steps)
Ctrl+Alt+→ / Ctrl+Alt+←	warmer / cooler
Ctrl+Alt+O	turn the screen off
Ctrl+Alt+D	show the panel
Ctrl+Alt+Q	quit

How it works

Each monitor gets two layered, click-through windows (WS_EX_LAYERED | WS_EX_TRANSPARENT, WM_NCHITTEST → HTTRANSPARENT):

1. a black layer that lowers brightness;
2. an amber layer above it that shifts the white point towards warm.

Using two layers instead of one keeps the two controls independent: warmth still reads at strong dimming levels. Everything is plain GDI/WinForms — no drivers, no gamma-ramp hacks, so a crash can never leave your screen stuck in an odd colour.

Screen-off uses the standard WM_SYSCOMMAND / SC_MONITORPOWER broadcast.

Settings

Stored in %APPDATA%\ScreenDimmer\settings.txt (level, warm, x, y). A small log lives next to it as dimmer.log.

Build from source

build.cmd

which calls the C# compiler that ships with .NET Framework and writes dist\ScreenDimmer.exe. The equivalent one-liner:

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe /target:winexe `
  /out:dist\ScreenDimmer.exe `
  /reference:System.Windows.Forms.dll /reference:System.Drawing.dll `
  src\ScreenDimmer.cs

build.ps1 does the same for CI and PowerShell users (run it with powershell -ExecutionPolicy Bypass -File build.ps1 if script execution is restricted on your machine).

CI builds the same binary on every push and attaches it to tagged releases.

Limitations

• It dims the picture, not the backlight: it does not save power the way lowering hardware brightness does.
• Warmth is a coloured overlay, so at maximum settings dark areas take a slight sepia tint — the usual trade-off of overlay-based dimmers.
• It does not cover the Windows sign-in screen or exclusive full-screen games.

License

MIT — see LICENSE.