Privacy Policy

Last updated: 20 October 2026
Applies to: Lustre for iPhone (App Store ID 6811636658, bundle com.dataconceptstudio.lustre) and Lustre for Android (Google Play, package com.dataconceptstudio.lustre)

This Privacy Policy explains how the app Lustre (the "App"), for iPhone and for Android, handles information. Lustre is published by Data Concept Studio Michał Szarek ("we", "us", "our"). The App uses your screen as an adjustable light for your face, with a mirrored front-camera preview. Where the two versions differ, this policy says so.

1. Who we are

The publisher of Lustre, and the data controller for any email you send us, is Data Concept Studio Michał Szarek, a sole proprietorship (jednoosobowa działalność gospodarcza) registered in Poland and based in Kraków, Poland. For any privacy question or request, contact contact@dataconceptstudio.com.

2. What Lustre collects

Nothing is sent to us. Lustre has no account and no sign-in, shows no ads, and Lustre's own code contains no analytics or tracking and makes no network requests. The only communication with a server is:

• iPhone: Apple's StoreKit talking to Apple for the trial check, the price, a purchase and restoring a purchase (section 5).
• Android: Google Play Billing talking to Google Play for the price, a purchase and restoring a purchase (section 5); and, only after you turn on the face-lighting hint, Google's ML Kit sending Google usage metrics (section 3.4).

3. Camera, photos and on-device features

3.1 Camera

Lustre asks for camera access to show a mirrored preview from the front camera. The permission text iOS shows is: "Lustre shows a mirrored preview from the front camera. Your camera image stays on your device and is never uploaded."

On Android the system shows its standard camera permission prompt.

The live preview is processed on your device only. It is never recorded, stored or uploaded. You can deny camera access and still use Lustre as a light.

3.2 Photos

A photo is saved only when you take one, and the App never reads your photo library or gallery.

• iPhone: Lustre asks only for permission to add photos to your library (permission text: "Lustre saves the photos you choose to capture to your photo library."). Your own iOS and iCloud Photos settings apply to saved photos.
• Android: Lustre asks for no storage or photo permission. It adds the photo to your device's shared Pictures/Lustre folder through Android's MediaStore, which needs no permission for an app's own photos. Your own gallery and backup settings apply to saved photos.

3.3 Room preset suggestion (iPhone only)

The Android version does not include this feature. On iPhone, to suggest a preset that matches the light in your room, Lustre reads the camera's own white-balance estimate (a colour temperature) in memory. This is an estimate, not a measurement. Nothing about it is stored or sent.

3.4 Face-lighting hint (off by default)

The face-lighting hint is off by default. You can turn it on in Settings ("Uneven light on your face"). When it is on, Lustre finds the rectangle around your face on the device and compares the brightness of the two cheek areas. The only result is which side, if any, is darker.

• iPhone: face detection uses Apple's on-device Vision framework.
• Android: face detection uses Google ML Kit with its model built into the App. The camera image and the detection results are processed on your device and are not sent to Google. ML Kit does, however, send Google technical usage metrics about the detector — device and app information, a per-installation identifier that is not intended to identify you or your device, performance figures, the feature's version and error codes — which Google uses for diagnostics and usage analytics, encrypted in transit. ML Kit only starts after you turn the hint on; until then it does not run at all. Google's handling of this data is described in the ML Kit terms and data disclosure.

No face image, face measurement or biometric identifier is stored by the App or sent to us or to Google. This feature is not face recognition: it does not identify who you are.

4. What Lustre stores on your device

Lustre keeps a few small files in its own private app storage. None of them are sent anywhere by the App.

Deleting the App deletes these files. Your device's own backups may include them under your backup settings: iCloud Backup on iPhone, and Android's backup to your Google account on Android (Lustre lets Android back up exactly these files, so that reinstalling on the same account keeps your settings, presets and trial date).

5. The free trial and purchases

• iPhone: Lustre uses Apple's StoreKit to check your free trial, show the price, make a purchase and restore a purchase. StoreKit communicates with Apple for these purposes. Apple's handling of this information is covered by Apple's own privacy policy and terms.
• Android: Lustre uses the Google Play Billing Library to show the price, make a purchase and restore a purchase. It communicates with Google Play for these purposes. The free trial is counted on your device from the date the App first ran (section 4) and involves no server. Google's handling of this information is covered by Google's own privacy policy and Google Play terms.

Purchases and payment are handled by Apple or Google, and we do not receive your payment details.

6. Third parties, analytics, advertising and tracking

• iPhone: no third-party SDKs.
• Android: Google ML Kit (only for the optional face-lighting hint, section 3.4) and the Google Play Billing Library (purchases, section 5). The other libraries in the App are Android's own Jetpack libraries, which collect nothing.
• No analytics or tracking in Lustre's own code. Lustre does not track you across apps or websites.
• No advertising.
• We do not sell or share personal data, because the App does not collect any.

7. When you email us

If you write to contact@dataconceptstudio.com, we receive your email address and whatever you put in the message. The "Contact us" row in the App's Settings opens your own mail app with a draft that already contains the App version, your iOS or Android version and your device model, to help us answer. The App sends nothing itself: the draft stays in your mail app until you send it, and you can edit or delete any part of it first.

We use your email only to answer you, and keep the correspondence only as long as needed for that. Data Concept Studio Michał Szarek is the controller of this data.

8. Retention and deletion

• Custom presets can be deleted in the App.
• Everything the App stores is deleted when you delete the App.
• Photos you took stay in your Photos library, and you delete them there like any other photo.
• Camera and Photos access can be withdrawn at any time in iOS Settings → Lustre, or Settings → Privacy & Security; on Android, in Settings → Apps → Lustre → Permissions.
• ML Kit (Android) is no longer used once you turn the face-lighting hint off; its per-installation identifier is reset when you delete the App.

9. Your rights

Under the GDPR you have the right to access, correct, erase, restrict or object to the processing of your personal data, and the right to data portability. Because the App sends us no personal data, these rights in practice concern any email correspondence with us. To exercise them, write to contact@dataconceptstudio.com. You also have the right to lodge a complaint with a supervisory authority; in Poland, that is the President of the Personal Data Protection Office (Prezes Urzędu Ochrony Danych Osobowych).

10. Children

Lustre has no account and we collect no personal data from anyone, including children. Lustre is not directed at children.

11. Changes to this policy

We may update this Privacy Policy from time to time. We will revise the "Last updated" date above. If a future version of Lustre changes how data is handled, this policy will be updated before that version is released.

12. Contact us

Data Concept Studio Michał Szarek, Kraków, Poland · contact@dataconceptstudio.com