Most people are familiar with a scanner for pictures and graphics but many have some misconceptions about how a document scanner works. A dedicated document scanner has some mechanical requirements that make it different from an image scanner. Although a document may be scanned on an image scanner, the scanning of documents usually entails storage of the scanned documents and this requires some special characteristics for a document scanner. Dedicated document scanners are used not only by companies with a large volume of documents but by companies that provide record-keeping services and by government agencies that process thousands of documents daily.
Scanning a letter to email to a friend is very different from scanning invoices or receipts as part of a company’s records. Using an image scanner for this purpose will prove not only inordinately slow but also prohibitively expensive. Speed and paper handling are the primary considerations for an efficient document scanner. A document scanner has a high-speed document feeder which can scan from 20 to 150 documents per minute. Most machines scan in grayscale for the sake of speed but some also have the capability to scan in color. Scanning resolution ranges from 150 – 300 dpi although some machines have higher capabilities that enable optical character recognition (OCR) without requiring additional storage capacity.
A higher-end document scanner can clean up the document being scanned, erase accidental marks, sharpen text and compress files for more efficient storage. A modern document scanner utilizes infrared cleaning to remove the dust and scratches from film that may interfere with the infrared light used in scanning documents in order to ensure clear document files.
The primary distinction of a document scanner as opposed to an image scanner is its capability of recording and organizing the scanned documents. OCR technology is utilized by a document scanner so that the files generated can be edited and searched. The scanned files are incorporated into a document management system, usually in a TIFF format, so that they can be archived and searched.
Manual work is still required in order to take full advantage of the facilities of a document scanner, most of it related to the preparation and indexing of the documents to be scanned. First of all, the physical condition of the documents has to be examined to make sure that they are not folded or stapled and that they are arranged in the proper order. Companies in the legal and medical industries may require additional marks such as Bates numbering to identify each document as well as the date and time of the scan. Some of the manual work may be automated through the use of barcodes so the scanned documents may be filed in specific folders.