ICAO 9303, MRZ and What a Document Reader Actually Captures

What ICAO 9303 defines

ICAO Document 9303 is the standard that makes machine-readable travel documents interoperable: the layout of the data page, the machine readable zone, and the chip in an electronic passport. A reader described as ICAO 9303 compliant can parse documents built to that standard regardless of issuing country — which is the whole point, since a front desk does not get to choose which passport arrives.

The MRZ is only text

The machine readable zone is the two or three lines of characters at the bottom of the data page. OCR of the MRZ gives you name, document number, nationality, date of birth, expiry and check digits. The check digits catch transcription errors. They do not tell you whether the document is genuine.

Why three illumination wavelengths

Full-page readers illuminate with white visible light (430-680nm), near infrared B900 (860nm) and UV A (365nm). Security features in modern documents are designed to respond differently under each. Capturing all three gives a record that shows what the document looked like under conditions a copy is unlikely to reproduce.

Contact, contactless and the chip

An electronic passport carries a chip. National ID cards may be contact smart cards to ISO/IEC 7816 Parts 1-4 (T=0 and T=1), contactless to ISO14443 Type A/B, or both. Driver licences may carry a PDF417 barcode instead. These are four separate reading capabilities, and a reader has each one or it does not.

Choosing between full-page and half-page

If your record needs to prove what was presented, you need a full-page imager at 400 DPI. If you only need accurate data entry — hotel registration, age verification — a half-page MRZ reader with a smart card slot is a lower cost per position and does the job.

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