0 PIXEL and PRINTERS

PIXEL

In Image processing and pattern recognition the smallest element of a digital image that can be assigned a gray level or in computer graphics, the smallest elements of a display surface that can be assigned independent characteristics. This term is derived from the term " picture element".

Speaker 

An electron - acoustic transducer that converts electrical signals into sounds loud enough to be heared at a distance . Synonymous with loud speaker.

Voice Response System 

A voice response system enables a computer to talk to the user audio response is an output media that produces verbal response from the computer system. In a voice response system all the sounds needed to process the possible enquiries are prerecorded on a storage medium. Each sound is given code. When enquiries are received the computer follows a det of rules to create a reply message in a coded form , This coded message is then transmitted to an audio response device. that assembles the sound in the proper sequence and transmits the audio message back to the station requesting the information voice response system is usually considered only for those appplication where there is a low speed human -machine interaction . The banking industry in the U.S.A is the largest user of voice response techniques. There are also many toys that teach and entertain young children using voice response units.

                                "Touch and Tell" toys that teach basic vocabulary and english have been developed for per school children.

             The bank are the largest users of voice response techniques . The bank computer gives voice response to telephone inquires of customers regarding the present position of their bank account. 

Multimedia Projector 

It is an output device connected to a pc and used to project information from a computer on toa large screen . The information is viewed by a large number of people . It is widely used for giving presetation. The presenter can directly point to mark or edit the displayed information to make it more understandable . Audio, vedio, image, and animation can be prepared on a PC and using a multimedia projector the presentation can be made more lively.

 PRINTERS

In computing, a printer is a peripheral that produces a representation of an electronic document on physical media such as paper or transparency film. Many printers are local peripherals connected directly to a nearby personal computer. Individual printers are often designed to support both local and network connected users at the same time. Some printers can print documents stored on memory cards or from digital camera and scanners.multi function printers (MFPs) include a scanner and can copy paper documents or send a fax; these are also called multi-function devices (MFD), or all-in-one (AIO) printers. Most MFPs include printing, scanning, and copying among their many features

There are two limitations of display output devices:

1. we can only see limited data at a time.
2. The output on screen is not transferrable and cannot be taken on paper.

 Both the above mentioned limitation can be overcome by printers as an output by device , that print the output on the paper. The output on the paper in printed from is called "Hard copy" . The digital signals sent from computer are converted to naturals language like Hindi, English, atc and then printed on paper by printer so that human being can understand.

They are mainly categorised in two classes such as :

1. Impact
2. Non Impact

On the basis of the working speed they are categorised as :

1. Low speed printers = It can print one characters at a time. 
2. High Speed printers = It can print output as single line or whole page at a time.

Types of Printing 

1. Impact Printing = This printing type resembles with the printing by typewriter. Inthis type of printer , a metallie hammer or a print head strikes on paper and ribbon to print characers . In impact printing characters are printed either as dot matrix or as solid fonts on the paper.  
2. Non Impact printing = In this printing method is no direct striking between print head and paper. Non impact printing can be of various type.

Types of Printers

1.