A small, free eye-comfort tool for Windows. It does four things and tries to do each of them properly.
| Warm | Colour temperature from 6500 K down to 1500 K |
| Dimmer | Screen brightness from 100% down to 10%, below what the monitor itself allows |
| Break | Eye-rest reminders on the 20-20-20 pattern, with a calm full-screen countdown |
| Text | Windows' own text rendering and UI font sizes: ClearType, stroke contrast, per-element sizes |
Warmth and dimming are written straight into the graphics card's gamma ramp, the same path f.lux and CareUEyes use, so they cover everything on screen including games, video and full-screen apps, with no overlay and no measurable cost.
Python 3.8 or newer on Windows 10/11.
pip install -r requirements.txt
Then double-click WarmDimmer.pyw. It starts in the tray with no console window.
If something goes wrong, run WarmDimmer-debug.bat to see the error.
For a single .exe, run build_exe.bat and look in dist\.
Each section carries its own toggle, because they do unrelated jobs and one master switch for all of them is a blunt instrument.
| Switch | When it is off |
|---|---|
| Warmth | Colour returns to neutral, dimming keeps working |
| Dimmer | Brightness returns to 100%, warmth keeps working |
| Eye rest reminder | Reminders stop, nothing else changes |
| Rendering (Text tab) | Windows' own font rendering comes back |
| Size (Text tab) | Windows' own text sizes come back |
| ON in the header | Pauses warmth and dimming together |
The two Text sections start off, so the app does not touch a single Windows setting until you ask it to. While a section is off you can still set everything up inside it: values are remembered and applied the moment you flip the switch.
Based on the 20-20-20 habit: every 20 minutes, look at something far away for 20 seconds. Both numbers are yours to change.
Two decisions separate a useful reminder from an irritating one:
It does not count time you were not there. Windows reports how long the keyboard and mouse have been idle, so stepping away counts as a break already taken. You will not sit back down to a reminder that was waiting for you.
It never covers a full-screen app. A video call, a game or a film is left alone; the reminder waits and appears the moment you are out of it. This matters most when you are sharing your screen in a meeting. You can turn that off if you would rather always be interrupted.
Every break can be skipped or postponed, and Esc skips. Take a break now
works from the tray whenever you want one.
This tab reaches what gamma cannot: the shape and size of Windows' own text. All of it is ordinary per-user settings, no administrator rights, applied instantly.
Rendering — ClearType on or off, subpixel or greyscale smoothing, subpixel order, and a contrast slider from 1000 to 2200. Contrast is the one that actually changes how heavy and how crisp the letter shapes are. A live preview line follows your changes.
Size — the Windows 11 accessibility text scale, plus per-element point sizes for the title bar, menus, dialogs, tooltips, small captions and icon labels. Windows removed the interface for those years ago; they still work. Bold is available for all six, and there is a desktop icon spacing slider.
Restoring. The first time you switch either section on, your original Windows
values are saved to %APPDATA%\WarmDimmer\windows_text_backup.json. Restore
Windows defaults puts every value back exactly and switches both sections off.
That file is never overwritten, so the original survives however much you change.
A note on MacType: MacType replaces the whole Windows font rasteriser by injecting a library into every running process. This tool does not do that and should not. It tunes Windows' own rasteriser instead, and the contrast slider in particular gives a real part of the same crispness with nothing injected.
| Action | How |
|---|---|
| Adjust | Drag a slider, scroll the wheel over it, or use the arrow keys |
| Presets | One click. Right-click one to overwrite, rename, reorder or delete |
| Save current values | + Save current |
| Hide | Esc, or Hide to tray. It keeps running in the tray |
Default hotkeys, all editable in Settings:
| Hotkey | Action |
|---|---|
Ctrl+Alt+Left / Right |
Warmer / cooler |
Ctrl+Alt+Up / Down |
Brighter / dimmer |
Ctrl+Alt+P |
Pause / resume |
Ctrl+Alt+W |
Show / hide the window |
Format is ctrl+alt+shift+win plus one key: a letter, a digit, f1–f24,
arrows, home, end, pageup, pagedown, numpad0–numpad9, punctuation.
- Steps & ranges — hotkey step size for warmth and brightness, the warmest and coolest limits, the darkest level, and the fade duration.
- Behaviour — start with Windows, start minimised, close button hides.
- Displays — choose which screens the app acts on.
- Unlock full gamma range — Windows limits how far the gamma ramp may move.
This writes
GdiIcmGammaRange=256to the registry, which needs administrator rights and a sign-out. Until then the app covers the missing dimming with a transparent overlay automatically. - Reset display — return the screen to normal immediately.
Settings live in %APPDATA%\WarmDimmer\config.json. You can edit it by hand; a
value that does not make sense is repaired at startup rather than stopping the
app from opening.
Display scaling. The API for it is undocumented, could not be confirmed to work reliably, and a bad value can leave the desktop at the wrong size until you sign out. Use Settings → System → Display → Scale.
Backlight dimming. It was built and measured: at 80% it keeps all 256 shades per channel instead of about 205, and cuts real emitted light rather than compressing the signal. It was removed again after testing, because lowering the backlight widens the gap between the screen and the lit room, and that gap is what tires the eyes. Signal dimming turned out to be the more comfortable of the two in practice.
- Only one instance runs. Starting it again brings the running window forward.
- The setting is re-applied every two seconds, because some apps and drivers reset the gamma ramp behind your back.
- Everything is returned to normal on exit.
MIT. See LICENSE.