Astigma

Astigma makes a Mac screen calmer to look at when brightness, glare, contrast, color, or display flicker are getting in the way.

It is deliberately simple:

1. Open Astigma.
2. Drag the large Comfort knob until the screen feels right.
3. Close the window when you are done setting it up. Cmd+W, Escape, and the red close button all hide the controls; Astigma keeps the display treatment running quietly in the background.
4. Open Astigma again whenever you want to adjust it. Use Quit when you want to stop it and restore the display.

What it changes

• A reversible software dimmer that can go below macOS’s normal brightness floor.
• Gentle transfer-table shaping for warmer whites and less harsh mid-tones.
• Balanced, Paper, Night, and Steady starting points.
• Optional per-display scope, warmth, soft contrast, paper tint, night schedule, and break rhythm.
• A hardware-aware workflow for displays whose low hardware-brightness range may be uncomfortable.
• Automatic recovery of a saved display transform after a crash or forced termination.

Astigma does not correct astigmatism, replace an eye prescription, or promise to eliminate PWM or temporal dithering. Persistent blur, double vision, pain, or headaches deserve an eye-care check. The technical rationale and measurement guide are in SCIENCE.md.

Full brightness + software dimming

The Steady path lets you choose a hardware brightness floor, then applies the remaining reduction in software. This may help on a panel that becomes steadier above its low-brightness PWM region, but the right level is display-specific. 100% brightness is not automatically best: glare and excess luminance can also be uncomfortable.

Astigma carries the main luminance reduction in the display transfer table, then uses the transparent overlay for the paper tint. That gives menu bars, fullscreen Spaces, and many system surfaces the same display-wide dimming. The overlay remains a fallback for displays that do not expose a writable transfer table. Astigma deliberately leaves the native macOS pointer untouched.

macOS-owned authentication UI—such as the Touch ID prompt shown by an installer—is a separate Security Agent surface. Apple does not provide a supported window level that can cover it. Astigma reasserts the display transfer table after Space/app transitions, but no third-party app can promise to override secure UI or an exclusive display mode.

Install and run

The app is a normal macOS application. After copying Astigma.app to /Applications, open it with:

open -a Astigma

The first window is the complete control surface. Closing that window hides the UI but leaves the display service active. Reopening the app brings the window back. Quit restores the display and stops Astigma.

Build from source

This project has no third-party dependencies and requires macOS 13 or newer.

swift run AstigmaChecks
swift build --product Astigma
NO_LAUNCH=1 ALLOW_ADHOC_TCC=1 ./devbuild.sh

The final command assembles and signs Astigma.app without opening it. Omit NO_LAUNCH=1 for a local development launch.

Safety and reversibility

Astigma captures the display transfer tables it changes, removes its overlay on Quit, and keeps a recovery record for the next launch if the process is interrupted. Pause or quit Astigma before calibrating a display or using another utility that writes display gamma tables.

Explainer video

Watch the nontechnical walkthrough: Astigma-Explainer.mp4. It explains the Comfort knob, Paper/Night/Balanced modes, Steady mode, and why full hardware brightness is a test rather than a universal recommendation.

Regenerate it locally with:

./Scripts/build-explainer.sh