6.100417 · Section 6: ICT applications

Recognition systems

Key learnings

Optical readers -- OMR, OCR, barcode and QR
OMR detects the position of a mark in a predefined box: a shaded box reflects less light back. Uses: registers, multiple-choice examination papers. OCR identifies the characters and outputs an editable text file, not a picture of the text; its use here is ANPR (car-park barriers, congestion charging, speed cameras). Barcode readers read bars and spaces encoding a number; QR readers read a 2D block pattern holding more, e.g. a web address.
RFID and NFC -- range, power and direction
RFID: a reader transmits radio waves that power a nearby tag (a chip on an aerial), which sends back its unique data. No line of sight is needed and many tags can be read at once, up to several metres away. Uses: tracking stock, passports, automobiles (keyless entry, tolls), contactless cards. NFC: short-range (a few centimetres) and two-way between two active devices -- named use: smartphone payment.
Biometric recognition -- the seven types
A biometric system reads a unique physical or behavioural characteristic and compares it with a digital template stored at enrolment. Face -- feature positions (eye spacing, jaw shape). Iris -- the coloured ring round the pupil, read by infrared. Retina -- blood vessels at the back of the eye. Finger/thumb -- the ridge pattern; hand -- shape and size. Voice -- pitch, tone and speech pattern. Part of the body, it cannot be forgotten or lent.

Common mistakes

Drawn from real examiner reports.

OMR reads position, OCR reads characters

OMR detects only where a mark is -- whether a box at a known location is shaded. It cannot tell what has been written there. OCR identifies which character has been written and turns it into editable text. Examiners note that echoing the words "marks" and "characters" back conveys no understanding: say what each one actually reads and how.

s23 P11 Q8

Marking exams is too vague as an OMR use

Naming a use of OMR needs the document type. "Multiple choice" is credited; "marking exams" on its own is judged too vague and earns nothing, because it does not show that OMR reads which answer box has been shaded. Apply the same precision to the other named use: a register is completed by shading a box against each name.

s23 P11 Q8

Compare the readers, not the tags

Asked to compare RFID with bar-code reading, candidates describe the tag and the printed code ("an RFID tag has a chip, a barcode has black lines"). The question is about the readers: an RFID reader needs no line of sight and reads many tags at once, whereas a bar-code reader needs a clear line of sight and reads one code at a time.

s23 P12 Q9 / s22 P12 Q5

Reads from a distance is not a difference

"It can read from a distance" is offered as the difference between an RFID reader and a bar-code reader, but it is true of both -- bar-code and laser scanners also read without touching the code -- so it distinguishes nothing and scores no mark. The credited differences are the line-of-sight requirement and reading several tags simultaneously.

s22 P12 Q5

The ANPR camera is not intelligent

Candidates describe the CCTV/ANPR camera as "intelligent", as though it read the plate by itself. An ANPR system is three parts: the camera only captures an image; the connected computer runs the OCR software that reads the characters; a database is then checked to decide the outcome. Credit is for that division of work, not for a "smart camera".

w23 P13 Q8

Internet failure does not switch ANPR off

If the internet connection fails, the system does not simply stop -- the barrier itself is still there. What is lost is the ability to check a plate against the central database and for the owner to monitor the car park remotely. An answer that says only "it stops working" has not identified what actually fails.

w23 P13 Q8

Real data is not real-time data

Real-time data is processed as it happens, with an immediate response -- the barrier lifts the instant a permitted plate is read. Real data only means genuine, non-fabricated data, which says nothing about how quickly it is acted on. The two are routinely swapped in answers about ANPR and other smart systems.

s23 P13 Q8c

Exam tips

Name the technology and what it reads
"It scans the document" scores little. State which technology is used -- OMR, OCR, RFID, NFC or a named biometric type -- and precisely what it reads: the position of a mark, the characters, the data on a radio tag, or a specific body characteristic.
An advantage needs a comparative
"The system is fast" is a benefit, not an advantage. Use a comparative against the alternative named in the question -- faster than a member of staff scanning each item -- and say whose advantage it is: the warehouse, the shop, or the customer.
Give the full reason for a misread plate
Plate-reading problems need the whole chain, not the word "error": a dirty or damaged plate, bad weather, or a letter that resembles a number obscures a character, so the OCR software reads the wrong registration and a permitted vehicle is refused.
Biometric vs manual: speed and accuracy
Comparing a biometric system with a manual or video-based check, the credited difference is speed and accuracy: automatic identification in seconds against a stored template, versus a guard comparing a face with a photograph, whose judgement tires and errs.

Revision notes