Basics of Internet & Computer application

                                                               Scanner 

                                                                                                                                                                                                                                                                      In computing, a scanner is a device that optically scans  image, printed text handwriting for an object, and converts it to a digital image.” Thus, a scanner converts a physical image to a digital computer-based image and transfers the image to an ASCII code and graphics. Thus, can be edited, manipulated, combined, and printed. Most of the scanners come with a utility program that allows it to communicate with the computer and save the scanned image as a graphic file on the computer. The scanner is an important input device and is widely used to directly feed some intricate data or images into the computer, which would otherwise be very difficult to feed.

”                                                                                                                                             Type of Scanner:-“The most common type of scanner are drum scanner, flatbed scanner, and handheld scanner. The details are given below.”                                                                                         1. Drum Scanner:-

They are named so due to the use of a clear acrylic cylinder the drum on which the original artwork is mounted for scanning . It can control sample arc and aperture size independently . This is parcularly  useful for smothing file grain while scanning black and white and color original .                                                                                                                                                                       only a few companies manufacture drum scanner now due to it high cost and comparitive  low demand .                                     2.Flat-bed:-

“They look similar to a photocopy machine. It is generally composed of a glass pane, under which there is a bright light that illuminates the pane and a moving optical array. Moves from top to bottom .For scanning a A4 size document, it takes about 20 seconds .These scanner can scan black and white as will as color imager .                                                                                                                                                   3.Hand-held scanner:-

A handheld scanner consists of light-emitting devices, which are placed over the material to be scanned. This scanner performs the scanning of the document very slowly, from the top to the bottom, with its light on. In this process, all the documents are converted and then stored as an image. While working, the scanner is dragged very steadily and carefully over the document, and it should move at a constant speed without stopping or jerking, in order to obtain best results. Due to this reason, handheld scanners are widely used where high accuracy is not of much importance. The size of the handheld scanner is small, they come be in various, resolution, and up to 800 DPI(dot per inch ) and are available in either grey scale or color .