How does the Scanner work

How does the Scanner work.
The scanners are the eyes of the personal computer. They allow the PC to convert a photo or picture into a code so that a graphics program or desktop publishing to produce it on the screen, print it to a printer
graphical or convert typewritten pages in pages being editoradas possible. The three main types of scanners
differ mainly as to the page (containing the image) and the scan head (that reads the image) jogging. On a sheet-fed scanner (sheet-fed), mechanical bearings move the paper through the scan head.

A flatbed scanner, the page is static over a glass, while the head moves across the page, as the machines
copiers. The hand-held scanners depend on the human hand to move the scan head.
Each method has its advantages and disadvantages. The flatbed scanner requires a series
of mirrors for storing the image captured by moving scan head and focused on the lenses that feed the image to a database
sensors. As no mirror is perfect, the image suffers some degradation each time it is reflected. But on the other hand, he can scan large or thick materials, such as a book. However, the sheet-fed scanner, the image is captured more accurately, but there is a limitation to work only with sheets of normal size.

The manual scanner is a middle ground. He is able to scan pages of books, but generally the scan head is not
as wide as the flatbed scanner. Most programs combine two scanner manual scans half page
in a single image. The hand scanner, which depends on the strength of the hand for accuracy, it is normally cheaper because no need a mechanism to move the scan head and not the paper.
The sophistication of the scanner is the ability to convert an unlimited amount of analog voltage levels
digital values. Some scanners are able to distinguish only black and white, being more used to text. The
more accurate models can distinguish shades of gray. The scanners use color filters red, blue and green
detect the colors in reflected light.
Regardless of the sensitivity of the scanner as gray and as the head and the paper moving, the mode of
all work is basically simple and similar. We will see the two most representative types of technologies involved
- The table and the manual grayscale. We will also see one of the main reasons to scan a document - convert
your image into editable text through the program of Optical Character Recognition (OCR).

Source: Evolution of Computers