Cross-device sync

If you calibrate on your iPhone in the morning at the studio and you want to find the curve in the afternoon on your Mac at home, you need a mechanism that carries the calibration from one device to the other. Without it, you go through AirDrop, email, a manual transfer of the

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Calibration Flow's cross-device synchronization solves this problem. You sign in with your Picturale account on each device, and your curves and presets propagate automatically between the two. When you open the app on the second device, you find what you did on the first. It's transparent — no "sync" button, no manipulation, just the authentication is enough.

#What syncs and what doesn't

What crosses over:

• The correction curves you've generated (the compact mathematical function, a few KB).
• The saved presets (the curve + parameters + name combination).
• The associated metadata (date, name, export parameters used).

What doesn't cross over:

• The imported source images (the targets, the final images intended for printing). They can weigh several MB each — multiplied by your dozens of imports, we're talking gigabytes. Too heavy for daily cloud synchronization.
• The generated negatives (the PNG export files). Same thing — too heavy, and reproducible from the source image + the parameters.

This boundary is deliberate. Sync is designed to transfer what's precious and compact — the calibrations that took time to produce — not to replicate your image library across all your devices. For that, use iCloud Photos or a personal cloud.

#What happens when you switch devices

You sign in to Calibration Flow on a new device (a Mac you've never used, for example). The app detects your Picturale account, makes a call to Firebase to retrieve the curves and presets associated with your identifier. In a few seconds, your library hydrates — you see your existing curves appear, ready to be applied.

If you make a new calibration on the Mac, it's saved locally and pushed to Firebase at the moment of saving. The next time you open the app on iPhone, that new calibration will be there.

If two devices modify the same preset at the same time (rare but possible — for example you work in parallel on two machines), the resolution strategy is simple: last write wins. No complex merge — the most recent change overwrites the previous one.

#Why it matters

For mobility. Studio + office + travel — three places, three devices. Without sync, you have to pick the main device and stick to it. With sync, you work wherever you are. The curve you made this morning waits for you tonight.

For limited collaboration. If you share your account with a trusted collaborator (an assistant, a production partner), you see the same calibrations. A calibration made by one is immediately available to the other. Not ideal for a formal team, but useful for a pair working together.

For implicit safekeeping. If your main device breaks down or is stolen, your calibrations aren't lost — they're at Firebase. You sign in on a new device, you find everything. Not a real backup strategy (Firebase is not a guaranteed backup service), but a protection against hardware accidents.

#When it doesn't work

In guest mode. If you use Calibration Flow without an account, nothing syncs — your calibrations stay trapped on the device. This is deliberate: an account is the technical condition of synchronization, because it defines the identity that ties the data together.

When the cloud quota is full. Synchronization is included from the free sign-up: your curves and presets are pushed to Firebase and come back down to your other devices signed in to the same account. The free account has 300 MB of cloud storage, Pro mode 5 GB. Beyond the quota, new data stays local until you free up space or upgrade to Pro.

Without a network connection. Your local changes are saved immediately on the device, but their transfer to Firebase waits for the connection. You can calibrate in airplane mode — sync will catch up as soon as you find the network again.

#Worth remembering

#The test

On your iPhone, generate and save a new calibration with a distinctive name (for example

test-sync-mai-2026

test-sync-mai-2026