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Unit 5: Computer Hardware

Figure 5.6: A View of Windows Screen for Recording of Voice
Notes

5.1.2 Special Input Devices

The input devices, which are not essential to operate a PC are called Special Input Devices. These
devices are required for special input operations. These devices include Scanner, Digital Camera,
Touch Screen, Light Pen, Trackball, Joystick, Digitizer, Optical Mark Reader, Optical Character
Reader, Bar Code Reader and Magnetic Ink Character Recognition (MICR) Device. Let us discuss
these.

Scanner
Scanner is widely used in Desktop Publishing (DTP) applications. It is used for digitising images
such as photographs, forms, documents, etc. into computer memory. There are many types of
scanners as shown in Figure 5.7. Some scanners can also read text by converting them to digital
code. The scanners are very useful for converting the typed pages into word-processing files.

Graphics scanners convert a printed image into video image without converting
it to digital code. You also need the software to install and use the scanner

Figure 5.7: Various Types of Scanners

Scanning of Images. A scanner is somehow like a photocopy machine. A photocopy machine copies
the contents of one page to another while a scanner stores the copy as an electronic image within a
file on disk. For displaying an image, the monitor combines different shades of three basic colours
(Red, Green and Blue), representing upto 16-million different colours. When you scan an image,
your scanner determines the image’s red, green, and blue colour components, and then saves them

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