Foundations of Digital Image

11. Optical Character Recognition (OCR) & Image Recognition

Optical character recognition, usually abbreviated to OCR, is the mechanical or electronic conversion of scanned images of handwritten, typewritten or printed text into machine-encoded text.

It is widely used as a form of data entry from some sort of original paper data source, whether documents, sales receipts, mail, or any number of printed records. It is a common method of digitizing printed texts so that they can be electronically searched, stored more compactly, displayed on-line, and used in machine processes such as machine translation, text-to-speech and text mining. OCR is a field of research in pattern recognition, artificial intelligence and computer vision.


CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot. For example, humans can read distorted text as the one shown below, but current computer programs can’t:


Image Recognition

The software for image recognition looks for patterns and sequences in numerical data. Each image is composed of pixels. The computer interprets the pixels as a series of numbers. If the computer can identify similar numerical series in multiple images, it can recognize that the images are all of the same subject.



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