QR and barcode scanner
The camera reads QR codes and barcodes and shows you what they contain. On recent Android versions the built-in camera often does this too — this is here so the toolbox is complete.
| Sensor used | Camera |
|---|---|
| Unit | Decoded text or URL |
| Useful range | Depends on code size, focus and lighting |
| Cannot do | Read badly damaged or very low-contrast codes, or perform general text recognition |
The mechanism, not the marketing.
The decoder looks for the distinctive finder patterns — the three squares in a QR code's corners, or the bar widths of a linear barcode — uses them to work out orientation and scale, then reads the encoded data.
QR codes carry error correction, so a partly obscured or slightly damaged code often still decodes correctly.
What a phone cannot do here.
- Focus and lighting dominate. Small codes need the camera close enough to focus, and glare on a glossy surface or a screen can defeat the decoder.
- A code that is torn, printed at low contrast, or heavily distorted may be beyond the error correction.
- Decoding a QR code does not make its contents safe. Always read the URL before opening it, because QR codes are a common phishing vector.
Do I still need a QR scanner app?
Often not — most recent Android camera apps scan QR codes natively. This is included so Sensor Lab covers the phone's hardware in one place, and it is useful when the built-in scanner is missing or awkward to reach.
Is scanning a QR code safe?
Scanning only decodes text. The risk is in what you do next, so check the URL before opening it.
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