What is a scanner?

What is a scanner?

A scanner is a device that captures images from photographic prints, posters, magazine pages and similar sources for computer editing and display.
Scanners work by converting the image on the document into digital information that can be stored on a computer through optical character recognition (OCR).
This process is done by a scanning head, which uses one or more sensors to capture the image as light or electrical charges.
The document scanner moves either the physical document or the scanning head, depending on the type of scanner. Then, the scanner processes the scanned image and produces a digital image that can be stored on a computer.
Scanners usually attach to a computer system and come with scanning software applications that let you resize and otherwise modify a captured image.
If a printer is hooked up to the computer, you could print a second hard copy of the scanned image and store it in digital format.
TYPES OF SCANNER
FLATBED SCANNER


Flatbed scanners will take up some desktop space but provide a lot of bang for the buck. They look like miniature printers with a flip-up cover protecting the glass platen. Flatbed scanners are some of the most commonly used scanners as it has both home and office functions. The way they scan documents is that a mechanism rolls under the document to obtain the image. For a businesses that have a need for high processing abilities, the flatbed scanner can scan any number of documents with a click of a button.


SHEET-FED SCANNER

Sheet-fed scanner is smaller in size than flatbed scanner. This type of scanner works like a flatbed scanner except that the document is fed through the scanner and moves along the beam to be read rather than the beam moving along document. This type is not useful for books, but only single sheets.

A small size is its advantage but improper mechanism can skew the paper.


DRUM SCANNER


Drum scanner is used for scanning a document and produce at very high resolution rate. There is no any type of scanner that will give you the kind of resolution, detail, sharpness, dynamic range, and color rendition that drum scanning can give you. There are only a few companies that make these scanners, considering the high cost of producing a scanner such as this. It is considered as a tremendous upgrade to a regular flatbed scanner.


A drum scanner uses a photo-multiplier (PM) tube, which is a light sensing device. That's why it offers a high sensitivity and good signal-to-noise ratio. The image to be scanned is placed on spinning.


HANDHELD SCANNER


Handheld scanner is much like a flatbed scanner. Handheld scanners are small helpful electronic devices that are widely used for digitizing printed documents. Handheld scanner provides lower quality scanners, they are still very popular because they are small and less expensive than their flatbed. They are able to scan items that could not fit in a flatbed scanner due to size or location. Their function includes moving them over the material being captured with the aid of a tray to keep it in a straight line. Experience is required to operate and handle the device since it is very important to keep the scanner straight so that a distortion-free scan is possible.


Low cost and portability is the advantages of handheld scanner but poor quality is its drawback.