Input Devices Topics to be discussed Optical Scanners

Input Devices

Topics to be discussed Optical Scanners Electronic Tablet/Pen Digital Camera Webcam Digitizers Speech Recognition

Optical Scanners Optical Mark Reader • Optical Character Reader • Bar-Code Reader • Magnetic Ink Character Recognition • Microphone •

Optical Mark Reader These scanners are capable of recognising a prespecified type of mark made by pen or pencil. The actual technique used by an OMR device for recognition of marks involves focussing a light on the page being scanned and detecting the reflected light pattern from the marks. Pencil marks made with a soft lead pencil(high graphite content) will reflect the light. For example: Consider sample question of an objective test and its answer sheet that can be read by an optical mark reader to grade the test is given below The Binary equivalent of decimal 7 is a) 101 b) 111 c) 001 d)100 a) b) c) d)

Optical Character Reader These scanner devices are capable of detecting alphabetic and numeric characters printed on the paper. These characters may be either typewritten or handwritten. In case of handwritten characters , the characters are of standard size, line making up the characters are connected and no stylish loops are used. In case of Typewritten characters, they must be typed using a special type font called an OCR font. OCR devices examine each character as if it were made up of a collection of pixels. Once the whole character has been scanned, it is compared with the characters(standard fonts), the machine has been programmed to recognize. Whichever pattern it matches, is considered to be character read. If the Scanned character does not match satisfactorily with any of the fonts, it is rejected.

Bar Code Readers It is a device used for reading(decoding) bar coded data. Bar code reading is performed by a laser scanner which is linked to a computer. The Laser beam is stroked across the Pattern of bits that is recorded as the input data. Different bar codes having different patterns of bars reflect the beam in different ways that is sensed by a light sensitive detector. Reflected light patterns are converted into electronic pulses and then transmitted to recognition logic circuits that convert it into an alphanumeric value. The most widely known bar code is the Universal Product Code(UPC) , which now appears on almost all retail packages in USA and now in India as well on many products. These bars are decoded as 10 digits. The first five of these digits identify the manufacturer or supplier of the product and the second five digits identify a specific product of the manufacturer.

Magnetic Ink Character Recognition MICR devices were developed to assist the banking industry for fast processing of large volume of cheques A Special type of cheque is used in banks that employ MICR devices. The bank identification code and customer’s account number is pre-printed on all these cheques with a special ink that contains magnetizable particles of iron oxide. Cheques can be fed directly into MICR device and processed automatically.

Microphone It is an input device to input sound which is then stored in digital form. This is then used for various applications like adding sound to a multimedia presentation or for mixing music. BACK

Scanners Scanner is a light sensitive device that helps you copy or capture images, photos, and artwork that exist on paper. A Scanner works on the principle of digitizing an image in the form of bit matrix called ‘bit-map’. The bit-map can be stored in a file, displayed on the screen and can easily be manipulated by relevant packages/programs. BACK

Electronic Tablet/Pen The tablet & pen in computer graphics describes an electronically sensitive tablet used in conjunction with an electronic stylus. The tablet is a flat surface , seperate from the CRT screen, on which user draws with the penlike stylus to input instruction or to control the cursor. It can also be used for selecting a portion of screen for enlargement of an existing image. It can also be used for selecting a function menu. It can also be used for Drawing on the screen or making stokes on the screen or tablet which indicates what image is to be drawn. BACK

Digital Camera Digital cameras are used to: • Download images to a computer • Post pictures to the Web • Produce videos Resolution is measured in megapixels Higher the resolution, better the image quality, but the more expensive the camera BACK

Webcam Web cam is a video camera that can be used to take images for uploading to the Web BACK

Digitizers A Digitizer is an input device used for converting(digitizing) pictures, maps and drawing into digital form for storage in computers. It contains a large smooth board an electronic tracking device which can be moved over the surface to follow existing lines. The electronic tracking device contains a switch for the user to record the desired X and Y coordinate positions. The coordinates can be entered into the computer memory or stored on an offline storage medium. High Resolution digitizers typically with a large board(e. g. 42 in. by 60 in. ) can provide resolution & accuracy on the order of 0. 001 inch. With the help of Digitizers, drawing can easily be changed. BACK

Speech Recognition Speech recognition is a type of input in which the computer recognizes words spoken into a microphone. Special software and a microphone are required. Latest technology uses continuous speech recognition where the user does not have to pause between words. BACK

THANKS