calibratr

Your photos, the way you edited them.

Out of the box, a monitor rarely shows what is in the file: too cool, too blue, with greys that drift in the shadows. Anyone who edits photos then corrects faults that are not in the picture at all. calibratr turns your iPhone into a measuring instrument for displays and makes your monitor trustworthy again.

Together with the free Mac app it calibrates your monitor. The Mac shows colour patches, the iPhone measures them in RAW: no image processing, no white balance, fixed exposure. The result is an ICC colour profile for exactly that display. White point, grey balance and tone curves are corrected, and the verification patches show in ΔE how well it went.

HOW IT WORKS • Open the Mac app and choose “Start calibration” • Scan the QR code on the screen with the iPhone. Both devices on the same Wi‑Fi, everything stays on the local network • Hold the iPhone a hand's width from the centre of the screen and start on the iPhone • One to ten minutes later the result is on the iPhone and the Mac: a before and after picture comparison, plus white point, gamma, contrast, gamut and grey balance

WHAT THE APP DOES WITHOUT A MAC The light meter reads any glowing surface, whether monitor, lamp or window, and shows colour temperature, white point, tint, exposure and signal-to-noise. It needs only the iPhone.

WHAT IT COSTS Measuring, the report and the picture comparison are free and stay free. The one-time purchase “Keep the result” unlocks installing the finished profile on the Mac: for all your displays, for good. No subscription, no account, no server.

WHAT IT CANNOT DO A phone camera is not a spectroradiometer. calibratr measures white point, grey balance and tone curves repeatably; it takes the position of the primaries from the monitor's factory profile. There is no absolute luminance in cd/m². If you need a reference instrument for prepress, you need a colorimeter.

REQUIREMENTS • iPhone with a RAW-capable camera, iOS 16 or later • For calibration: the free Mac app (calibratr.app.freshx.de), macOS 13 or later

PRIVACY No accounts, no analytics, no advertising. Shots are reduced to readings on the device and are neither stored nor transmitted. iPhone and Mac connect directly over your Wi‑Fi.