The Visual Inspection Zone (VIZ) and its special challenges in document analysis
Check Visual Inspection Zone
While the Machine-Readable Zone (MRZ) already bears its advantage in its name, the so-called Visual Inspection Zone (VIZ) is not quite so self-explanatory.
This article is therefore dedicated to the structure and special features of the VIZ in document capture and verification.
The document 9303 of the International Civil Aviation Association ICAO defines the standards for machine-readable travel documents.
More than 190 countries are committed to these guidelines. They apply them to machine-readable passports, visas and ID cards. Within countries, the design of identity and travel documents is the responsibility of the relevant authorities.
Often, these are under the authority of the Ministry of the Interior.
To enable standardization, the ICAO divides the identity document into different zones to which specific data sets are assigned.
On the personal data side, we distinguish two zones:
- The Visual Inspection Zone (VIZ). The data group of this zone includes the photograph, the document designation, personal data and the date of issue and validity of the document.
- The Machine-Readable Zone (MRZ). In the two to three lines of the MRZ, information from the viewing zone is strung together with alphanumeric characters and the "<" symbol. The requirement for the MRZ is that all information can be read by special devices, such as DESKO document scanners, thanks to so-called OCR (Optical Character Recognition) fonts. This is an important difference to the data groups of the Visual Inspection Zone.
We note that the personal data of the document holder are present several times on his identity document: They are found in the Visual Inspection Zone and in the Machine-Readable Zone. In the case of electronic passports, they are also stored on the microchip.
Accordingly, the viewing zone contains relevant personal data. However, there are no specifications for the presentation of this data. Neither the fonts or font sizes to be used nor the arrangement of the data groups are defined in a binding manner. How can this part of the ID document still be recorded or checked with the help of technical equipment?
If the personal data in the Visual Inspection Zone is viewed as individual data groups with text information, it can be captured by machine. DESKO customers use our ID Collect® software for this purpose. With this software, we not only capture text data automatically, but also offer a knowledge database with which the meaning of the individual text fragments can be used automatically. For example, for the data first name, date of birth, document number, etc.
The development of such software requires special know-how, knows Tobias Langhammer, Senior Software Engineer at DESKO:
"Because VIZ is not designed for machines, there are always exceptions and anomalies. Usually, the infrared image of the document is used for optical character recognition because the text can be seen there without any disturbing background. Rarely, however, there are documents that are not readable in IR light or where disturbing elements are still visible in IR. We also develop solutions for such special cases. Not all text fields are always available. The positions of the text fields also vary. The fact that ID Collect® can read non-Latin fonts from the VIZ is a real special feature that we have worked on intensively as a team. This is a huge advantage for our customers."
When checking ID documents, the consistency of data from different zones of the document plays an important role. And vice versa: data that does not match is often an indication of manipulated or forged documents.
The information from the VIZ is almost indispensable, especially for application areas in which data from ID documents has to be processed digitally. In manual workflows, when data is copied or typed from the document, the source of errors is high. Especially with rare document types. With software solutions such as ID Collect®, an interface solves the problem: the data from the VIZ is read by the DESKO ID scanner and transferred to existing programs, forms or software via the interface.