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Un Common Computer Input DevicesUn Common Computer Input Devices - Digital Scanner - Digital Camera - Microphone - Optical Readers - OCRMicrophone Microphone is an input device used to enter the sound signals of user into the computer. It is used to record the voice of the user in a computer. It is also used to talk to others on the Internet. The user talks to another user on the Internet by sending his message through the microphone and receives the response on the speaker attached to the computer. For this purpose you must have the microphone and a sound card with your computer. The sound card translates the sound signals (analog) into digital signals for processing by computer. The sound card can also translate the sound digital signals back into analog signals and then sent to the speaker. Some computers have the capability of understanding spoken words and thus data can be entered with the help of microphone. Such facility is called Voice Recognition. Voice recognition software use a database of already entered spoken words. This database is used to recognize the words spoken by a computer user. A user, therefore, thinks that the computer understands whatever he speaks on. Today, microphone is becoming important as input device to record speech. Most personal computers now have phone-dialing capabilities, if you have a microphone with an earphone, you can communicate with others through your personal computer. You can also use a microphone to record your voice and can store it in a file on disk. This file can be sent by e-mail to others. Digital Camera Digital Camera is an input device used to take pictures and to store directly in computer in digital form. It operates on the same basic principle as a traditional or conventional camera but digital camera sends images directly inside the PC in digital form instead of storing it on a conventional film. When a picture is taken with digital camera, the electric image of the picture is stored in digital form on the floppy disk or CD-R attached with the camera. The stored picture can be loaded into the computer from the disk for editing. Digital Scanner Digital scanner is a very popular input device. It is a light-sensing input device. It reads images and text printed on the paper and then translates into electronic form that can be processed and stored by the computer. The scanner is also known as image scanner. The scanner uses the laser technology to scan the image of the printed paper and store it into the computer. Once an image is scanned, it can be used for following purposes.
Can be transferred to the paint program for processing or it can be directly opened in the word processing program for editing. The software is used to manipulate the scanned image. For example, if you have scanned text document then you might have to use optical character recognition (OCR) software to translate the image into text for editing. Similarly, if you have scanned a photo then you might have to use the Adobe Photoshop graphic software to adjust its colors, size etc. Optical Readers An optical reader is a device that uses a light source to read characters, marks printed on the paper etc. and then converts them into digital form that can be stored and processed in computer. These devices are similar to digital scanners. There are two main types of optical readers.
1) Bar Code Readers Data coded in the form of light and dark lines or bars are known as bar codes. The bar codes are particularly used for labeling products (or goods) and books in public libraries. The code number on the product or book is represented by a pattern of vertical bars. The most widely used bar code is the Universal Product Code (UPC). Bar-Code Reader is an input device used for reading (or decoding) bar codes on the product or book. The most common type of bar code reader is the flatbed model, which is commonly used in super markets and departmental stores. The bar code reader reads the bar code printed on the product and converts into a code the computer can understand. The bar-code reader contains the photoelectric cell or light- sensitive detector that reads the bar code by means of reflected light. The bar-code reader emits a laser beam of light that is reflected by a bar code pattern. The bar-code reader decodes the bar code and then records into computer as input data. 2) Optical Character Recognition (OCR) The OCR devices (or scanners) are used to scan special characters (such as alphabetic and numeric characters) printed on the paper and fed into the computer as input data. The OCR device also uses a light source to read the characters printed on the paper. The characters printed on paper may be typewritten or handwritten. In case of handwritten, the characters must be of standard size but in case of typewritten, the characters must have the special type font called an OCR font. The accepted OCR fonts are OCR-A (American standard) and OCR-B (European standard). The OCR software is used to translate the scanned image of text document into text. When OCR device creates an image from a page, the image is stored in the computer’s memory as a bitmap. A bitmap is a grid or array of dots and each dot is represented in memory by one or more bits. The OCR software translates the array of dots into text or number. The characters that match with the standard OCR fonts are stored into the computer and others are rejected. The scanned text document can be edited with the help of word processor. OCR devices are expensive and are used by credit card companies, large businesses for following purposes.
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