An optical reader is a device that converts text or images from paper into digital signals that can be processed in various ways by computers. In all cases, the reader is taking a scan of the printed text or image, and converting it to a digital file suitable for a computer processor. The resulting file can be then be used to convert the text to speech, spell check a letter, or scan a bar code at a sales counter for a retail sale.
Text scanners for digital processing of books, letters, and images have been widely used since the late 20th century. A growing interest in digitally preserving old documents and manuscripts led to libraries creating archives using optical reader technology. Many digital files are stored on public computer servers, and are available through the Internet.
Voice generation from text is another use for optical reader technology. The reader software uses the scanned image of a book or letter, and creates a file that "reads" the text with a computer-generated voice. Voice readers are very useful for the blind or vision-impaired that cannot read printed text. Starting in the late 20th century, some web sites could be voice-generated directly from a web page, with no additional scanning required.
Another type of optical reader is the laser bar code scanner. This scanner used a low-power laser beam to scan a series of codes appearing as black and white bars of varying width on retail packages and labels. A computer recognized the number code represented by the bars, which could be used for identifying an item being purchased. Bar codes were also widely used on shipping packages, where automated machines in sorting warehouses read the codes and directed packages to their correct shipping truck or container.
Beginning in the 20th century, an optical reader was developed that could identify markings on tests, election ballots or voting cards for corporation shareholders. The reader could detect black or dark blue marks made in specific circles or boxes on the card or letter. These readers simplified vote or test processing over manually reading all the cards. Incomplete or incorrect marks and optical reader problems happened occasionally and votes were re-counted to minimize errors, reducing the effectiveness of these systems.
An enhanced optical reader technology developed in the late 20th century was the digital matrix scanner. Bar codes had limitations in the total digits that could be represented, because each digit had to have a bar of a specific width and size. Using a matrix or box, made up of smaller black or white boxes of different sizes, allowed the information capacity of a code to expand greatly. More information simply required a box of different dimensions or size, and improvements in the readers allowed the boxes to be smaller, also improving the amount of information contained in them.
Mobile phones developed in the late 20th century often had an integrated camera. Applications were developed that could recognize the codes in a digital matrix image captured by the phone camera. No scanning was needed, because the software used the camera image directly. Retailers at the time were rapidly expanding use of matrix codes for linking customers to their website, sending information requests directly to the phone, among other uses.