Image scanner

Film scanner, for photographic slides

In computing, an image scanner is a device used to transfer images or text into a computer. There are special models for scanning photo negatives, or to scan books. In the computer, the signal from the scanner is transferred to a digital image. This image can then be edited, printed, etc. All scanners have special parts which are used to take a picture from an object.

Charge-coupled device or Contact Image Sensor parts take the light from the object and change it into a digital signal. The digital signal is then transferred to the computer memory or is read in the scanner's processor. With some software it can be changed to a compressed digital image, like JPEG or PNG. Text printed or written by hand can be changed to ASCII code by an OCR program.

Types

The main types of scanner

Desktop scanner (flatbed scanner). This is probably the most popular type. An object to be scanned (picture, image, text sheet) is put on the glass. Under the glass, there is a moving Image Sensor.
Hand scanner. The device is moved on the paper by hand. It was popular during the 1990s.
Rotary scanner (drum scanner) used for fast scanning large numbers of sheets of paper.
Smartphone scanner scans a document by taking a photo with the smartphone's camera.^[1]

Producers

Canon
HP
Lexmark
Mustek
Plustek
Other

Image Scanner Media

A flatbed scanner. Documents or images are placed face-down beneath the cover (shown closed here).
Pantelegraph
Caselli's pantelegraph mechanism
Belinograph BEP2V wirephoto machine by Edouard Bélin, 1930
The first image scanner developed for use with a computer was a drum scanner. It was built in 1957 at the US National Bureau of Standards by a team led by [[Russell A.
Scanner unit with CIS. A: assembled, B: disassembled; 1: housing, 2: light conductor, 3: lenses, 4: chip with two RGB-LEDs, 5: CIS
DSLR camera and slide scanner
A hand scanner with its interface module.
A photographic print being scanned into a computer at the photo desk of the Detroit News in the early 1990s.