12.2 Section 12: Frictionless UI & Hands-Free Operation

Red Light Mode strict red/black

Entire UI rendered in red-on-black for darkroom use.

Where to find it

Settings Red Light Mode

Summary

Red Light Mode converts every pixel on the screen to red-on-black using a color matrix filter, preserving night vision and film safety in a darkroom. The UI remains fully functional: you can still measure, adjust settings, and navigate, but only in red light wavelengths. Toggle in Settings under Red Light Mode.

Tap to zoom — actual screenshot from the app

Detail

How it works

What it does

Turn it on and the entire app — buttons, text, overlays, everything — turns red. Black areas stay black, white areas become medium red, gray areas become dim red. The math preserves perceived brightness so the UI is still readable.

When to use it

Darkrooms and other situations where you need to preserve night vision. Red light is the longest visible wavelength; film is less sensitive to red light than to blue or green, so you can work safely without fogging your negatives.

Important note

Red Light Mode disables brightness lock. In a darkroom the ambient light is zero so auto-brightness is useless anyway; manually adjust your phone brightness to what feels safe for your film stock and keep it there.

What you can do in Red Light

Everything. Measure light, adjust metering modes, browse your shot log, check settings. The meter stays fully functional; only the colors change.

Implementation notes (for developers)
redLightModeEnabled boolean in Profile. Applied via ColorMatrix in MainActivity composing (R,G,B) -> (luminance * 0.8, 0, 0). Brightness lock is disabled when Red Light is active because darkroom conditions require manual brightness control. Persists across reboots.

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