Know and understand characteristics, uses, advantages and disadvantages of Optical Character Recognition (OCR) including automated number plate recognition (ANPR) systems

ICT Applications – Optical Character Recognition (OCR)

What is OCR?

Optical Character Recognition (OCR) is a technology that converts different types of documents – such as scanned paper documents, PDF files or images captured by a digital camera – into editable and searchable data by recognising the printed or handwritten characters within the image.

Key Characteristics

• Uses pattern‑recognition algorithms to match shapes of characters to known fonts.
• Can process printed text, typed text, and, with advanced engines, cursive handwriting.
• Works on a variety of image sources: scanners, digital cameras, mobile phones.
• Often includes pre‑processing steps (de‑skewing, noise reduction, binarisation).
• Outputs editable text formats (e.g., .txt, .doc) and can retain layout information.

Common Uses of OCR

• Digitising printed books, newspapers and archives.
• Automating data entry from forms, invoices and receipts.
• Enabling searchable PDFs and electronic document management systems.
• Assistive technology for visually impaired users (text‑to‑speech).
• Processing licence plates in traffic monitoring – see ANPR below.

Advantages of OCR

• Reduces manual data‑entry time and associated human error.
• Facilitates rapid searching and retrieval of information.
• Improves storage efficiency by converting paper to digital files.
• Supports workflow automation and integration with other ICT systems.
• Enhances accessibility of printed material.

Disadvantages of OCR

• Accuracy can be affected by poor image quality, unusual fonts, or complex layouts.
• Handwritten text is still challenging for many OCR engines.
• Initial set‑up and training of specialised OCR software may be costly.
• Requires post‑processing (proofreading) for critical documents.
• Potential privacy concerns when scanning sensitive documents.

Automated Number Plate Recognition (ANPR)

What is ANPR?

Automated Number Plate Recognition (ANPR) is a specialised application of OCR that reads vehicle registration plates from images captured by cameras, typically used in traffic enforcement, toll collection, and security monitoring.

How ANPR Uses OCR

The ANPR process combines several steps:

1. Image acquisition – a high‑speed camera captures the vehicle as it passes.
2. Plate localisation – image‑processing algorithms detect the rectangular region containing the plate.
3. Pre‑processing – contrast enhancement, de‑skewing and noise removal.
4. Character segmentation – individual characters are isolated.
5. OCR engine – recognises each character and assembles the registration number.
6. Database lookup – the number can be compared against watch‑lists or used for billing.

Advantages of ANPR

• Enables rapid, non‑intrusive identification of vehicles.
• Improves road safety by detecting unregistered or stolen vehicles.
• Automates toll collection, reducing congestion at payment booths.
• Supports traffic flow analysis and urban planning.
• Operates 24/7 under various lighting conditions with infrared illumination.

Disadvantages of ANPR

• Accuracy can drop in adverse weather, dirty plates, or unconventional fonts.
• High initial investment for cameras, lighting, and processing hardware.
• Potential privacy and data‑protection issues if vehicle data is stored improperly.
• Requires regular maintenance (cleaning lenses, updating software).
• May produce false positives/negatives, necessitating human verification.

Summary Table – OCR vs. ANPR