multimedia & cg

8/20/2019 Multimedia & CG

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COMPUTER GRAPHICS & MULTIMEDIA

1. GRAPHICS:Graphics is the visual and pictorial representation of any object according to the idea andimagination of the developer or designer. Graphic is an art of the science drawing. Graphicsdesign is a creative process that most often evolving a client and designer. Graphics is themost important tool for displaying results after processing the data which is given by a user.Graphics is that system which produce the results in pictorial form for better easilyunderstand. When a user provides some inputs to the system for processing then system will

give results in the form of images or in the form of Graphics. Graphics provides us interfacebetween the user and hardware. When a user is performs his task by using any applicationprogram in the computer then produced the result of those operations after processing whichare shown to the screen in Graphics form. Everything which you saw on the display screen iscalled as Graphics. A Graphics may a single picture, multiple pictures, any box etc. Graphicsare always made through as inputs provided by user. Every nput of a user will cause theoutput or dsplay of the picture.

!he term computer graphics has been used in a broad sense to describe "almost everythingon computers that are not text or sound#. !ypically, the term computer graphc! refers toseveral di$erent things%

the representation and manipulation of pictorial data by a computer.

the various technologies used to create and manipulate such pictorial data .

the sub&'eld of computer science which studies methods for digitally synthesi(ing and

manipulating visual content.

". COMPUTER GRAPHICS:)omputer graphics is concerned with producing images and animations *or se+uences of images using a computer. !his includes the hardware and software systems used to makethese images. !he task of producingphoto&realistic images is an extremely complex one, but this is a 'eld that is in great demandbecause of the nearly limitless variety of applications. !he 'eld of computer graphics hasgrown enormously over the past -/0 years, and many software systems have beendeveloped for generating computer graphics of various sorts. !his can include systems forproducing 1&dimensional models of the scene to be drawn, the rendering software for drawingthe images, and the associated user interface software and hardware.

)omputer graphics is an art of drawing images and objects according to mathematical lawsand rules as in perspective projection and the interest. )omputer graphics is a method todisplay our creations in pictorial mode. ")omputer Graphics is a subject to investigategraphics representation, generation, processing and display by using )omputers". )omputerGraphics is one of the most active branch in computer science. !oday computers andcomputer graphics are an internal part of daily life for everybody. )omputer graphics has agreat impact on today2s technology. )omputer graphics is in daily use in the 'elds of science,engineering, medicine, entertainment, advertisement, the graphic arts, the 'ne arts, business,education and training to mention any idea. With the help of it, we can represent and generatethe model of every ideas or imaginations. 3o, computer graphics are graphical representationand manipulation of image data created using computers. )omputer Graphics is the use of computer to de'ne, store, manipulate, interrogate, and present pictorial output.

)omputer graphics is a complex and diversi'ed technology. )omputer graphics represents

'nally, a picture or image where the picture may be used for a large variety of purposes like %it may be an engineering drawing, a business graph, an architectural rendering for a proposedconstructions or design project, an image for a medical procedure or a single frame for ananimated movie. )omputer graphics is the most important and easy method for represent ourthough in to image or picture mode. We can design the model of every idea of every 'eld in

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U#IT: 1 COMPUTER GRAPHICS &MULTIMEDIA


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graphical shape and show and see that easily. )omputer graphics provides methods togenerate images using a computer. An image can represent a realistic scene from the realworld, but graphics like histograms or pie charts as well as the graphical user interface of asoftware tool are also considered as images.

!he development of computer graphics has made computers easier to interact with, andbetter for understanding and interpreting many types of data. 4evelopments in computergraphics have had a profound impact on many types of media and have revolutioni(edanimation, movies and the video game industry."A picture is worth a thousand words" is awell&known saying, and highlights the advantages and bene'ts of the visual presentation of our data. !he picture is the fundamental cohesive concept in the computer graphics.)omputer imagery is found on television, in newspapers, for example in weather reports, orfor example in all kinds of medical investigation and surgical procedures. A well&constructedgraph can present complex statistics in a form that is easier to understand and interpret. nthe media "such graphs are used to illustrate papers, reports, theses, and other presentationmaterial". 3o, computer graphics has become an essential part of today2s technology. t is thelife line of today5s computer world. !oday, computers and computer&generated images touchmany aspects of daily life. 6any powerful tools have been developed to visuali(e data.)omputer generated imagery can be categori(ed into several di$erent types% 04, 14, 74, andanimated graphics. As technology has improved, 14 computer graphics have become morecommon, but 04 computer graphics are still widely used. )omputer graphics has emerged as

a sub&'eld of computer science which studies methods for digitally synthesi(ing andmanipulating visual content. 8ver the past decade, other speciali(ed 'elds have beendeveloped like information visuali(ation and scienti'c visuali(ation more concerned with "thevisuali(ation of three dimensional phenomena like architectural, meteorological, medical,biological etc. , where the emphasis is on realistic renderings of volumes, surfaces,illumination sources, and so forth, perhaps with a dynamic *time component".

. SOME COMPUTER GRAPHICS TERMS:I%teract$e Graphc!:

!he word interactive graphics means the set of technologies used to create art with computersor the art or designs created using such technologies. Generally a Graphics is shown by user

when he re+uests for some applications program. nteractive graphics is a computer graphicssystem that allows the operator or user to interact with the graphical information presented onthe display using one or more of a number of input devices, some of which are aimed atdelivering positions relevant to the information being displayed. Almost all computerworkstations and personal computer systems are now able to be used interactively. nteractivecomputer Graphics like a website, it is only useful if it is browsed by a visitor and no twovisitors are exactly alike. t means the website must support the interaction of users with avariety of skills, interests and end goals. nteractive computer graphics involves the user2sinteraction.

An interactive Graphics provides a facility to represent any Graphics. nteractive Graphics arethose which are made by user, means all the attributes of a Graphics are depend upon the

user input. Application model provides these features for changing display of a Graphics andmany times a programmer wants to make his Graphics according to his needs and aprogrammer may also creates or changes or modi'es any Graphics. Application 6odels thoseare also called as Geometric and 9on&Geometric Graphics and also some directed Graphsthose are used for displaying objects in Graphical form. n Geometric form like :abels , ;oxes,:ines etc. and in 9on&Geometric Graphics include some textual information and also somenumeric data or a user inputs.

"D Computer Graphc!:04 computer graphics are the computer&based generation of digital images mostly from two&dimensional models, such as 04 geometric models, text and digital images. !he word maystand for the branch of computer science that comprises such techni+ues, or for the models

themselves.

04 computer graphics are mainly used in applications that were originally developed upontraditional printing and drawing technologies, such as typography, cartography, technicaldrawing, advertising etc. n those applications, the two&dimensional image is not just a



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representation of a real&world object, but an independent artefact with added semantic value<two&dimensional models are therefore preferred, because they give more direct control of theimage than 14 computer graphics, whose approach is more related to photography than totypography.

D Computer Graphc!:

14 computer graphics in contrast to 04 computer graphics are graphics that use a three&dimensional representation of geometric data that is stored in the computer for the purposesof performing calculations and rendering 04 images. 3uch images may be for later display orfor real&time viewing.

4espite these di$erences, 14 computer graphics rely on many of the same algorithms as 04computer vector graphics in the wire frame model and 04 computer raster graphics in the'nal rendered display. n computer graphics software, the distinction between 04 and 14 isoccasionally blurred< 04 applications may use 14 techni+ues to achieve e$ects such aslighting, and primarily 14 may use 04 rendering techni+ues.

,. HISTOR4 O5 COMPUTER GRAPHICS:We need to take a brief look at the historical development of computer graphics to placetoday5s system. )omputer Graphics concept is also started with the invention of computertechnology. =istory of the computer graphics we can include from the earliest text characterimages or from non&graphic mainframe computers to the latest photographic +uality imagesand high resolution personal computers. !he 'eld of computer graphics dates back to theearly ->?2s with van 3utherland, one of the pioneers of the 'eld. !his began with thedevelopment of the *by current standards very simple software for performing the necessarymathematical transformations to produce simple line&drawings of 0& and 1&dimensionalscenes. As time went on, and the capacity and speed of computer technology improved,

successively greater degrees of realism were achievable. !oday it is possible to produceimages that are practically indistinguishable from photographic images.The 1*6S era:)omputing and calculating electronic devices were invented in ->@7&7 A.4. n the 7s erathe output devices were character based system so, there were used alphanumeric andsymbolic based pictures. !he images created or designed in this era were dark and lightcharacters. )rude plotting of hardcopy devices such as teletypes and line printers were widelyused in that era. !he Whirlwind )omputer which is known as the 'rst display unit developedin ->7 at the 6assachusetts nstitute of !echnology *6! ,nited 3tates had computer&driven )B! displays for output. !he *3emiautomatic Ground Environment 3AGE Air&4efence3ystem developed in the middle 7s. t was the 'rst command and control using )B! displaythat consoles on which operators identi'ed targets with light pens*hand&held pointing devicesthat sense light emitted by objects on the screen.n this era Crofessor )oons designed theconcept of D)A4# *)omputer Aided 4esign in ->7 and )oons surface in ->?@.

The 1*-6S era:n the -?sbeginning there were modern interactive graphics output as the vector graphicstechni+ues. !he modern interactive graphics started with the inventions of a 6! student van3utherland7s 3ketchpad drawing system*software in ->?1 at the :incoln :ab. 3o, =e is knownas a father of computer graphics. t was a 6an&6achined Graphical )ommunication 3ystem.3ketchpad was the 'rst program that is ever utilise a complete Graphical ser nterface. tused a :incoln !F&0 computer display unit *vector based monitor. And also developedinteractive technologies that used the keyboard and light pen for making choices, painting adndrawing. n that ?s era released very simple computer generated 'lm by ;oeing2s Dibrationsof an Aircraft#. ;6 released the ;6007 graphics terminal that was the 'rst commercially

available graphics computer .n ->?- a 6! student 3teve Bussell created the 'rst video gamenamed" 3pacewar". A scientist E. E. Hajac at ;ell !elephone :aboratory *;!:, created a 'lmcalled "3imulation of a two&giro gravity attitude control system" in ->?1.



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Also in ->??, 3utherland at 6! invented the 'rst computer controlled head&mounted display*=64. n ->? !ektronix introduced the storage&tube )B!, which permanently retains adrawing until the user erase it. n ->?, another such devices were invented. !he refreshdisplay hardware for geometric transformations could scale, rotate and translate points andlines on the screen at real time. !hese systems could perform the 04 and 14 clipping andproduce parallel and perspective projections. n the late ->?2s, a Irench engineer Cierre;e(ier creates ;e(ier curves and ;e(ier surfaces that are now used in most )A4 and computergraphics systems.

The 1*86S era:n the J5 S output system started using raster display system. !he graphical display was stillfairly chunks. n the era of J s there was one of the most important advancement in computergraphics as the microprocessor *)C. A number of animation houses were formed including:ucas'lm *George :ucas, creators of the 3tar Wars 'lms. n ->J7 6andelbrot describes IractalGeometry. Iractals are used in computer graphics to create realistic simulations of naturalphenomena such as mountains, coastlines, wood grain, etc. !he 'rst major advance in 14computer graphics was created at *tah niversity by these early pioneers, the hidden&surface algorithm. With this algorithm the computer determines which surfaces are Dbehind#the object from the viewer2s perspective, and thus should be hidden when the computerrenders the image. n ->J, ;ouknight proposed the 'rst lighting reKection model which isalso known as Kat shading. n ->J-,Gourand developed Gauraud 3hading method that

presents a method for creating the appearance of a curved surface by interpolating the coloracross polygons. n ->J7, Chong proposed a local lighting model named as Chong lightingmodel which was one of the most important and inKuential lighting model. !he developmentof inexpensive raster graphics, based on television technology in early seventies contributedmore to the growth of the 'eld. !he Baster displays stores displays stores display primitives*lines, characters or areas in a refresh bu$er.

The 1*+6S era:n the early ->s, the availability of bit&slice and -?&bit microprocessors started torevolutionise high resolution computer graphics terminals which now increasingly becameintelligent, semi&standalone and standalone workstations. !he ->3 era outputs were built&inraster graphics, bitmap image and pixel. n this era !urner Whitted came up with the idea of

Bay tracing. !his was a new rendering method for simulating highly reKective surfaces. n Lanuary->@ Apple computer released which was the 'rst personal computer with graphicaluser interface. !he 6acintosh remains a highly popular tool for computer graphics amonggraphic design studios and businesses. n this era personal computer cost decrease, trackballand mouse become the standard interactive device. 6odern computers, dating from the ->soften use Graphical ser nterface *G to present data and information with symbols, iconsand pictures, rather than text. n ->@, the researchers of )ornell niversity and =iroshimaniversity introduced the concept and methods of radiosity in the 'eld of heat radiation tocomputer graphics.

The 1**6S era:n the->>s era after the introduction of GA *ideo Graphics Array and 3GA *3uper ideo

Graphics Array, the personal computers can easily display photo&realistic images and movies.n this era became more popular in gaming, multimedia, and animation world. 3ince then,computer graphics have only become more detailed and realistic, due to more powerfulgraphics hardware and 14 modelling software. Irom >s there started revolution in computergraphical 'lms also. "!oy 3tory" was the 'rst commercially successful full&length computer&generated animation 'lm released in ->>7.After than !erminator, ;atman, Lurassic Cark etc.movies were released. ";eauty and the ;east " movie released with many scenes contained14 animated objects which were Kat shaded with bright colours. n 0> there released"Avtar" movie with full feature and very high color +uality 14 scenes.

Early computer graphics started as a research and application 'eld that was the domain of only a few experts, for instance in the area of computer aided design *)A4. 9ow a days, we

can see various arti'cial activities in the graphical world. )artoon 'lms, animated 'lms, with14 high resolution. Any person using a personal computer bene'ts from the developments incomputer graphics. 8perating systems and application programs with graphical userinterfaces *Gs belong to the simplest applications of computer graphics. isualisationtechni+ues, ranging from simple histograms to dynamic 14 animations showing changes of



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winds or currents over time, use computer graphics in the same manner as popular computergames. Even those who do not use a personal computer might see the results of computergraphics on ! or in cinemas where parts of scenes or even a whole movie might be producedby computer graphics techni+ues. )omputer graphics involved in the various 'elds likesimulation, medical diagnosis, crime&enactment, cartoons and 'lms etc.

. HISTOR4 O5 COMPUTER GRAPHICS I# ASPECT O5 #EPAL:;efore researching about the history of )omputer graphics in 9epal we must have knowledge

of development of computer system in 9epal. !he history of computer in 9epal is not that oldsince 9epal has not given any contribution in the development of evolution of computer. n0-;.3. there was brought electronic calculator named Iacit in 9epal for )ensus purpose. twas electronic calculation device. t was in 00 ;.3. when =6G brought ;6 -@- *a 3econdGeneration computer on rent for Bs. - lakhs and 07 thousand per month to process censusdata. !his computer was G based system but not high graphical supporting device. :ater thecomputer was bought by 9ational )omputer )enter *9)). n 01 ;.3., a fourth generationcomputer ): 0>7M- was imported with the aid of 94C and 9ICA from England for 0lakhs 3 dollars. !his computer had ?@ terminals and it is kept in museum now. Ior this reasona separate branch called Nantrike 3anrinikarm Ondra*Electronic 4ata Crocessing center wasestablished in ->J7 *01- ;.3. which after six years was converted to 9ational computercenter *9)).

At that time ;ritish Government helped to develop manpower of 9)). n the meantime9epalese students went to ndia, !hailand and 3A for the computer education themselves. n01> ;.3., microcomputers such as Apple, ector, 3ins, etc were imported by privatecompanies and individuals. 6icrocomputers such as Apple, ector and 3irus were introducedin Oathmandu for the 'rst time in ;.3. 01> *->1. 6any private companies like )omputer)onsultancy *)), management nformation Crocessing 3ystem *6C3, 4ata 3ystemnternational *43, etc were established. 3uch private companies started selling computersand training people in other to produce manpower in 9epal itself. )omputer graphics system isalso improved the advancement according to invention of advance devices. n 0?1 6uni;ahadur 3akya assembled the Iirst 3uper )omputer in 9epal by combining sixteenmicroprocessors. 3ince 0?0M?1 the graphical system emerging fastly in 9epal. arious

companies also established to developed various softwares and applications. n 0?0 ;.3.*07 A.4. Bodiant nfotech 9epal *C. :td. *B9! was established in 9epal to serve thecountry in the )omputer Graphics 'eld. n 0?1 ;.3. *0?A.4. Webtech 9epal, Weblink9epal, ;roadway nfosis 9epal and more many companies established after then. 9owadays,several graphical designing systems are available in 9epal. n Iilm ndustry, there is alsoinvolvement of computeri(ed modeling and designing. !he 'rst 9epali 'lm with the graphicale$ect is "Neti ko Ohoji 6a" of :axman ;asnet produced in Oathmandu by isual Croduction Cvt.which is released in Iebruary 0?J;.3. !he 'rst 14 movie"igilante" of 4ependra OumarOhanal produced by Aasma Iilms Croduction Cvt. in )haitra >,0J ;.3.

9owadays, computers with faster processing and larger storage are found cheaply in 9epalesemarket. 3tudents are given computer education from school level. At present )omputerAssociation of 9epal *)A9 is the governing body of 9epal. 9ow&a&days probably each andevery institutions, business organi(ations, communication centres, ticket counters etc areusing computers. )omputer graphics educations are also getting by the students to design theG based softwares and other applications. 9ow a days ,there are various educational centresare teaching about the computer graphics and animation topics as short term course also.Adobe Chotoshop, Animated systems are widely using to modify the picture and to createanimated objects. 9epalese 'lm industry is also now a days improving their technologies andusing advance high graphical systems to produce the high resolution movies and scenes.

-. APPLICATIO# O5 COMPUTER GRAPHICS:)omputer graphics started with the display of data or hard copy plotter and )B! screens hadgrown include the creation, storage and manipulation of mode is of images of objects. !hesemodels come from a diverse set of 'elds and include physical mathematical, engineering,architectural, natural phenomena and so on. !here is virtually no area in which graphicaldisplays cannot be used. !oday almost all application programs even for manipulating text ornumerical data uses graphics extensively in user interface for visuali(ing and manipulating theapplication speci'c objects. Graphical interaction has replaced textual interaction withalphanumeric terminal. Even people who do not use computer encounter computer graphics in

! commercial or special e$ects. t is an integral part of all computer user interfaces and is #a$% Maa 're%(ra%agar 11 Arport Sur)het *+,+1-1- E/Ma0S)maa,23ahoogma.com


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independence for visuali(ing 04, 14 and higher&dimensional objects. We 'nd computergraphics used in a diverse areas as science, engineering, medicine business, industry,government, art, entertainment, education and others.-. )omputer Aided 4esign 7. Entertainment0. Cresentation ?. isualisation1. )omputer Art J. mage processing@. Education and training . Graphical ser nterface

1. COMPUTER AIDED DESIG# 9CAD:)omputer Aided 4esign also referred as )omputer Assisted 4esign. t is the system whichconsists the use of computer systems to assisting the creation, modi'cation, analysis oroptimi(ation of design. t is sometimes known as computer&aided design and drafting *)A44.A )A4 system is a combination of hardware and software. !his system is used to increase theproductivity of designer, improve the +uality of design, improve communications throughdocumentation and to create a database for manufacturing. )A4 has been a major drivingforce for research in computational geometry and computer graphics *both software andhardware.Architects, drafters, architectures, engineers and artists use )A4 software to createplans and construction drawing. n )omputer Aided 4esign, interactive graphics is used todesign components and systems of mechanical, electrical, electromechanical and electronicdevices including structures such as buildings, automobile bodies, aeroplane, textiles, spacecraft, watercraft, ery large scale integration chips, optical systems and telephone andcomputer networks.

With the advent of computer graphics, that the model could now be changed into a full 1&4rendering. With this advantage, automobile makers could animate their moving parts and testthem. Architects are using interactive graphics methods to layout Koor plans that showspositioning of rooms, doors, windows, stairs, shelves and other building features. !heemphasis is on interacting with a computer&based model of the component or electrical orthermal properties.

". PRESE#TATIO# GRAPHICS:Another major application area of computer graphics is the DCresentation Graphics#.Cresentation Graphics are used to provide illustrations for reports or to generatetransparencies for use with graphics. Cresentation Graphics is commonly used to summari(e'nancial, statistical, mathematical, scienti'c and economic data for research reports,managerial reports and other types of reports. !ypical examples are bar charts, line graphs,surface graphs, pie charts and other displays showing relationship between multiple variables.

!he 14 graphics are usually used simply for e$ects, they can provide a more diagrammatic ormore attractive presentation of data relationship.

. COMPUTER ART:)omputer graphics is used to generate arts. !hey are widely used in both 'ne art andcommercial art applications. A 'ne art is drawn by artist hand and this kind of art is perfect tothe artist skill. Artist use a variety of computer methods including special purpose hardware,artist paints brush program, other paint packages, specially developed software. 6athematicspackages, )A4 packages, desktop publishing software and animation packages providingfacilities. 6oreover, an artist uses a touchpad or a stylus or digiti(er to draw pictures. !hemovement of object is captured by some input hardware. !hese arts are usually generated byusing mathematical functions or algorithms. )omputer art is not a realistic as 'ne arts. 6ostlythe commercial art is used to produce animations to demonstrate or present commercialproducts to the public. Iind artists use a variety of computer techni+ues to produce images.

!hese images are created using a combination of 14 modelling package, texture mapping,drawing programs and )A4 software. !hese techni+ues for generating electronic images arealso applied in commercial art for logos and other design, page layouts combining text andgraphics, ! advertising sports, and other areas. Animations are also used fre+uently inadvertising and ! commercial and produce frame by frame, where each frame of the motionis rendered and saved as an image 'le.

,. EDUCATIO# A#D TRAI#I#G:)omputer graphics is used in education and training 'eld for making it more e$ective andmore illustrative. !o represent the teaching materials more interesting and attractive asdiagrammatic and graphical form computer graphics can be used. Ior example% if a teacher isto teach bonding of molecules or electron jump from higher energy state to lower energy state



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or the structure of gene. !hen he can demonstrate these concepts using computer graphicssoftware or presentations. Another example could be taken for surgery. A student can learnsurgery using data gloves and realistic computer graphics. !his way the cost of education willbe low and risk of human life as well. 8ther examples could be Kight simulator and drivingsimulator for pilot and driving training. 6odes of physical systems, physiological systems,population trends or e+uipments such as the color coded diagram helping trainees tounderstand the operation of the system.

. E#TERTAI#ME#T:)omputer graphics methods are new that commonly used in making motion pictures, musicvideos and ! shows. mages are drawn in wire&frame form and will be shaded with renderingmethods to produce solid surfaces. Graphics objects can be combined with the line action.)omputer graphics are also used to introduce virtual characters to movies like character invarious movies like :ord of the Bings, gore, 3herk etc. )omputer graphics is also widely usedfor gaming purpose. arious high de'nition games like God of War can be created usinggraphical software package.

-. ;ISUALI


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Graphical ser nterfaces have become key factors for the success of the software oroperating system. G uses graphical objects called gi(mos *a gadget to represent certainobjects or process involved in human computer communication for virtual purpose. :ots of aesthetics *colors and psychological analysis have been done to create user friendly G. !hemost popular G is windows based G. Windows vista is the latest G based operatingsystem. !he G creators are putting having emphasis on 14 G creation.



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GRAPHICAL I=O DE;ICES:A computer is only useful when it is able to communicate with the external environment.

Be+uired devices to operate the computer whatever necessary devices or optional devices arealso useful for the computer graphics. When you work with the computer you feed your dataand instructions through some devices to the computer. !hese devices are called nputdevices. 3imilarly computer after processing gives desired output through other devices calledoutput devices. !he input Moutput devices provide the capability of communication of computer system with its important devicesMcomponents which is in external environment.

!hey are also known as Ceripheral devices. nput devices are used to enter data andinformation from outside world to primary storage or main storage. And these devices performthe activity of inputting .8utput devices supply the results of processed operation fromprimary storage to the user. ;oth nput and 8utput devices used for perform input and outputfunction in the system.

Role of Graphical Input/output devices:-. nput M8utput devices provide the capability of communication of computer system with

its important devices, components which is in external environment.0. nput Moutput devices are peripheral devices and external devices of computer systemand important part for the computer graphics.

1. 3ome of these devices are play the role of major components for the computer graphicsand some of these devices are used as the re+uirements of the user to create, modifyand improve the graphical object.

@. 4ata and instruction can be entered in to computer through input devices in the form of typing *text, voice and picture.

7. Beceives processed information from computer and provides them to the user ingraphical display form *soft copy output or printed form*=ard copy output .

". GRAPHICAL I#PUT DE;ICES:

arious =ardware devices as input devices, scanning devices, pointing devices and outputtingdevices are used for the computer graphics. !hese all devices are also named as interactive

graphics devices. nput device are used to feed data or information into a computer system.

!hey are usually used to provide input to the computer upon which reaction, outputs are

generated. Graphics input can be in a form of voice, text or image. !o enter any type of data

there used the re+uired graphics device. 4ata input devices like keyboards are used to provide

additional data to the computers in the form of text whereas pointing and selection devices

like mouse, light pens, touch panels are used to provide visual and indication&input to the

application. arious scanners like 8ptical )haracter Beader *8)B , ;ar code Beader*;)B

types of devices are used to enter data into the computer in the form of image or picture..

!hese devices read the raw data prepared by the user and send them in to the computer as aseries of electronic pulse. !he input device established the communication link between user

and the computer system. nput devices are necessary to convert our information or data in to

a form which can be understood by the computer. A good input device should provide timely,


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accurate and useful data to the main memory of the computer for processing followings are

the most useful input devices.

Categor3 o> commo%3 u!e( graphca %put (e$ce!:-. Oeyboard devices %Oeyboard

0. Cointing and drawing or :ocator devices%6ouse, !rackball, 3pace ball, Loystick, :ight

Cen, !ouch 3creen

1. 4ata 3canning devices %mage 3canner, 8)B, 86B, ;)B, 6)B@. Electronic card based devices % )ard reader, A!67. 4igiti(er

?. oiceM3peech Becognition devices% 6icrophone

Some o> the Graphca I%put De$ce!:1. Data Go$e:

4ata gloves are based on the concept of virtual reality. 4ata gloves can be used to grasp aDvirtual# object. t is constructed with a series of sensors that detect hand and 'nger motions.Electromagnetic coupling between transmitting antennas and receiving antennas is used toprovide information about the position and orientation of the hand. !he transmitting and

receiving antennas can each be structured as a set of three mutually perpendicular coils,forming a three&dimensional )artesian coordinates system. 4ata gloves are one of the severaltypes of electromechanical device used in haptics application i.e. the science of applyingtactile sensation to human interaction with computer.

". Touch/Pa%e: !ouch panels are a sensitive surface that is used to point directly. !he panel can be touched by'nger or any other object like stylus transparent touch panels are integrated with computermonitor for the manipulation of information display. !ouch panels allows the users to point atscreen directly with a 'nger to move the cursor around the screen, or to select icons.A basictouch panel senses voltage drop when a user touches the panel. t knows where the voltage

has dropped and accordingly calculates the touch position. Iollowing are the mostly usedtouch panels%

• 8ptical touch panels

• 3onic panels or acoustical touch panels

• Electrical touch panel

An optical touch panel uses nfrared *B emitters and sensor on F and N&axis sides, emitter areplaced and on the opposite sides sensors are placed when a user touches the screen, the pointwill interrupt two B beam from F and N&axis. !his is detected by B sensors and the touchposition is calculated.n Acoustic *3ound based touch panel uses very high fre+uency *7 6h(. !he sound waves aregenerated from F&axis and N&axis sides are reKected from opposite side of either axis. Whenuser touches the panel, the sound waves are interrupted and reKected back from their midwave. !he sensors on the F&axis and N&axis sides measured the time, the sound waves took toget reKected back and estimate the touch position.



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Besistant based touch panel uses two substances of glass or plastic separates by insulators.When a user touches the panel these two substances are connected and the resistance at thatpoint will drop down. !he resistance drop is sensed and the touch position is calculated.n capacitance based touch panel, some charge is spread on the screen. When user touchesthe panel the charge is drawn by 'nger form each side proportionally. !he sensor calculatesthe charge in fre+uency of chargeMvoltage and 'nd out the touch position.

Advantages:

• !ouch panel can be mounted on display screen leaving more space on desktop butmouse, joystick etc. take some space.

• Crovides easier environment to operate.

. Ta?et!:Generically, a ta?et PC refers to a laptop or slate&shaped mobile computer, e+uipped with atouchscreen or graphics tabletMscreen hybrid to operate the computer with a stylus or digitalpen, or a 'ngertip, instead of a keyboard or mouse. A common device for drawing, painting orinteractively selecting co&ordinate position on an object is a digiti(er. !ypically a digiti(er isused to scan over a drawing on object and to input a set of discrete coordinate position whichcan be joined with straight line segments to approximate the curve surface shape. 8ne type of digiti(er is Graphics tablets *data tablets, which is used to input two dimensional *04 co&ordinate by activity a hand curser or stylus as selected position, Kat surface. A hand curser

contains cross hairs for sighting position, while a stylus is a pencil shaped device that ispointed to the position of the tablet. 6any graphics tablets are constructed with a rectangulargrid of wires embedded on the tablet surface. !his form factor o$ers a more mobile way tointeract with a computer. !ablet C)s are often used where normal notebooks are impractical orunwieldy, or do not provide the needed functionality. Electromagnetic pulses are generated inse+uence along the wires and an electric signal is induced in a wire coil. n an activated stylusor hand curser to record tablet position. Acoustic *3onic tablets use sound waves to detect astylus position. Either strip microphones or point microphones are used to detect the soundemitted by an electrical spark from a stylus tip. !he position of the stylus is calculated bycalculating the arrival time of generated sound at di$erent microphone position.

3peci'cally, Ta?et PC refers to a product announced in 0- by 6icrosoft, and de'ned by

6icrosoft to be a pen&enabled computer conforming to hardware speci'cations devised by6icrosoft and running a licensed copy of the "Windows FC !ablet C) Edition" operating systemor a derivative therefore.

A($a%tage! o> Ta?et!:• t is a digiti(er

• 3can over an object and create discrete co&ordinate positions

• !hese points can join in a tiny straight line segments to appropriate shape of the original object

• )an be moving stylus*pencil&shaped device or puck*like mouse with cross hairs for sighti

position held

in user2s hand&si(e varies from ?x? inches up to @xJ0 inches or more.• Accuracy below .0 mm.

,. Dgt@er:4igiti(er is an input device used for converting picture, maps, and drawings into digital formfor storage in computers. t is a common input device for drawing, painting, or interactivelyselecting coordinate positions on an object. A digiti(er consists of a digiti(ing tablet also calledgraphic tablet associated with a stylus. A digiti(ing tablet is a Kat surface that containshundreds of 'ne copper wires forming a grid. t is used to scan over a drawing or object and toinput a set of discrete coordinate positions that can be joined with straight /line segment toapproximate the curve or surface shapes. 8ne type of 4igiti(er is the graphics tablet or datatablet which is used to input two dimensional or a three dimensional space.

. GRAPHICAL OUTPUT DE;ICES:8utput is the action of getting information from the computer. t is processed information andresult that produced through several output devices. 8nce the )C has executed the program



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instruction, may ask that information be communicated to on output device. 8utput devicesare those hardware which accept processed result from the primary memory and supply it tothe users or store it to secondary device for future use. !he output devices translate the dataprocess in the computer from machine code to human code. 3ome output devices produce theoutput on the screen or voice system and some output devices produces output as the printedmaterial. !he output devices have two forms%

3oftcopy output devices *4

=ardcopy output devices

So>tcop3 output (e$ce! 9;DU: A softcopy output is an output, which is not printed onpaper or on some material. 3oftcopy output cannot be touched and cannot be carried forbeing shown to others. t is temporary in nature and vanishes after use. !he informationdisplayed on the monitor disappears as soon as you turn o$ the monitor. !he output displayedon a terminalM monitor screen or spoken out by a voice response system is an example of softcopy output. 3oftcopy devices enable viewing of work, which allows correction andrearrangement of materials to suit speci'c needs. 6onitor, Crojector, and 3peakers are theexamples of softcopy output devices. !he softcopy devices do not contain expenditure onstationary and the output can be seen faster. !he pproperties of video display devices arepersistence, resolution, and aspect ratio.

Har(cop3 output (e$ce!: A =ardcopy output is an output, which is printed on paper or on

some other materials. t can be touched and carried for being shown to others. !hey arepermanent in nature and can be kept in paper 'les or can be looked at a later time when the

person is not using the computer. !hey can be kept safely for the future use. Crinters, Clotters

are the examples of hardcopy output devices. !he hardcopy output cannot be changed and

modi'ed later. !he output produced by the hardcopy output devices can be reused for the

longer time.

S#.

SO5TCOP4 OUTPUT DE;ICES HARDCOP4 OUTPUT DE;ICES

-. Croduced result through softcopy outputdevices is temporary in nature.

Croduced result through hardcopy outputdevices is Cermanent in nature.

0. 3oftcopy output devices produce result

on the monitor screen or spoken out bythe speaker.

=ard copy output devices produce result

as printed material.

1. !he output produced through softcopyoutput devices is not printed on thepaper.

!he output produced through hardcopyoutput devices is printed on the paper.

@. !he output produced through softcopyoutput devices can be changed andmodi'ed easily.

!he output produced through hardcopyoutput devices can not be changed andmodi'ed.

7. 3oftcopy output material can also besaved into electronic medium like harddisk, pen drive etc. for future use.

=ardcopy output material can not besaved into electronic medium.

?. 3oftcopy output can be produced throughdevices are faster than hardcopy output.

=ard copy output can be producedthrough devices are slower than softcopyoutput.

J. 6onitor, 3peaker, 6ultimedia Crojectoretc. are examples of 3oftcopy output

Crinter, Clotter etc. are examples of =ardcopy output devices.



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device.

1. Mo%tor 9;!ua D!pa3 U%t: !he most popular output device is the isual 4isplay nit *4. t is sometimes referred as

isual display terminal *4!. t is also called the monitor. 6onitor is the display screen used to

display the text and graphics, allowing users to view the result after processing of data

entered through input devices. 6onitor is used to display the input data and to receive

messages from the computer. t is the most common and popularly used output device forproducing softcopy output. t displays the generated output on a television like screen. A

monitor has its own box which is separated from the main computer system and is connected

to the computer by cable. n some systems it is compact with the system unit.

Mo%ochrome Mo%tor: 6onochrome word is made by mono P chrome where "mono"

indicates one and "chrome" indicates color. 3o, 6onochrome monitors show their images in

one color but these perform displaying function as background color and foreground color *!wo

colors. 3ometimes it referred as ;lack and white monitor. !hese monitors are used for text&

like displays. !he display color of the monochrome monitor can be black and white, green and

black, amber *yellowish&brown and black.

Coor Mo%tor: !he color monitors display anywhere from -? to - million di$erent colors.)olor monitors sometimes called BG; because they accept three separate colors red, greenand blue. An BG; monitor consists of a vacuum tube with three electron guns&one each forred, green and blue colors. )olor monitors are sometimes classi'ed by the number of bits theyuse to represent each pixel. !he electron guns 're electrons at the phosphorous coatedscreen. When the electron beams excite the phosphors dots they glow. )olor monitors areoften classi'ed by the number of bits they use to represent each pixel. !he more bits per pixel<means the more colors the monitor can display. Ior example a 0@&bit monitor represents eachpixel with 0@&bits.

DISPLA4 TECH#OLOGIES:1. REFRESH CAH!"E#RA$ %&E: !he most popular output device is the isual 4isplay nit *4. t is sometimes referred asisual display terminal *4!. t is also called the monitor. 6onitor is the display screen used todisplay the text and graphics, allowing users to view the result after processing of dataentered through input devices. t is the most common and popularly used output device forproducing softcopy output. 4i$erent types of monitors have di$erent technologies used inthem but the operation of commonly used monitors is based on )athode Bay !ube *)B!!he'rst )B! developed by Ierdinand ;raun in ->J in Germany.

!he monochromatic )B!5s used for graphic displays are essentially the same as those used inblack&and &white home television sets. Every monitor has an electronic gun which creates or

emits a beam of electrons *electrons means cathode rays or some signals. A electron beam,emitted by an electron gun which passes through focusing and deKection systems. !he beamof electron strikes at speci'ed points on the phosphor coated screen. !he phosphor then emitsa small spot of light at each position contacted by the electron beam. !he light of phosphorfades after sometime. 3o electrons beam is repeated +uickly to redraw picture in the screen



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on same point. !he phosphor in screen is of di$erence persistence. !he turn persistence isused to represent time internal during which phosphor emit after beam is removed. !hephosphor may have low or high persistence. f persistence is low then it will be suitable foranimation. f persistence is high it will be used for display highly complex pictures in )B!. Weuse cathode to heat the electrons. )athode is heated by 'lament. !he electrons areaccelerated toward phosphor coating by high positive voltage. 8ne way to keep the phosphorglowing is to redraw the picture repeatedly by +uickly directing the electron beam back overthe same point. !his type of display is called a refresh )B!.

t consists of the following main parts % )B!, Electron gun, Iocusing system, 4eKection system,phosphor coated screen. 4escription of the above parts given below%Eectro% Gu%: At the back of the monitor is a set of electron guns which produce a controlledstream of electrons. !o produce a picture on the screen, these guns start at the top of thescreen and scan very rapidly from left to right. !hen they return to the left&most position oneline down and scan again, and repeat this to cover the entire screen. !he primary componentsof an electron gun in a )B! are the heating 'lament, cathode and control grid.!he heat isapplied to the cathode by directing a current through a coil of wire n the )B!, is called'lament. When current is passed through a coil of wire *'lament, the cathode gets heated.

!his causes electrons to be emitted from the hot cathode surface. !he negatively chargedelectrons are accelerated toward the phosphor coating by a high positive voltage.Co%tro Gr( : t is a metal cylinder which is used to surround the cathode. Grid is cylindrical

in shape. Grid has hole at one end, through which electrons get escaped. !he control grid iskept at lower potential as compared to cathode, so that a electrostatic 'eld can be created. twill direct that electrons through point source, so process of focusing will be simpli'ed. A highnegative voltage applied to the control grid will shut o$ the beam by repelling electros andstopping them from passing through the small hole at the end of the control grid. !hebrightness of picture can be controlled by adjusting follow of electrons and current in beam.5ocu!%g S3!tem: t is needed to force the electron beam to converge into a small spot as itstrikes the phosphor. Iocusing is accomplished with either electronic or magnetic 'elds. Withelectronic focusing, the electron beam passes through a positively charged metal cylinder thatforms on electrostatic lens. Electrostatic focusing is commonly used in television and computergraphics monitors. !he magnetic focusing system is achieved by setting up a coil mountedaround the outside of the )B! envelope. Additional focusing hardware is used in high&

precision systems to keep the beam in focus at all screen positions.Deecto% S3!tem: t is also called as yoke. 4eKection system directs the electron beam at aparticular point on the screen. !he deKection plates are used to control the deKection of theelectron beam. !wo pairs of deKection plates are used with each pair mounted on the oppositeside of the neck of the )B!. 4eKection of the electron beam can be controlled either withelectric 'elds or magnetic 'elds through the deKection plates. )athode&ray tubes arecommonly constructed with magnetic deKection coils mounted on the outside of the )B!envelope. 4eKection system consists of two pairs of coils. 8ne coil control hori(ontaldeKection, whereas other control vertical deKection. !he deKection coils deKect theinformation rapidly so that it can be displayed clearly on the screen. !he proper deKectionamounts are attained by adjusting the current through the coils.Pho!phor: t is a substance that can emit light when irradiated with particles of

electromagnetic radiation. t is also known as a special organic compound. A variety of phosphor available at the end of the )B!. Chosphor has di$erent colors . )olor generally usedis white. White color is suitable for dark background. t should have high eQciency in term of electric energy converted into light. When the phosphors emit light that is calledphosphorescence.



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n raster scan display, the electron beam return to the left of the screen after refreshing eachscan line, is called hori(ontal retrace of the electron beam. n raster scan display, at the end of one frame, the electron beam returns to the left top corner of the screen to start the nextframe, is called vertical retrace of the electron beam.

". COLOR CRT:)olor monitors are sometimes called BG; monitors. A color )B! monitor consists of a vacuum

tube with three electron guns&each for red , green and blue at one end and the screen at theother end. !he electron guns are arranged either in a straight line or in a triangularcon'guration but the guns are usually constructed as a single unit. !hese three electron guns're electrons at the screen, which contains a phosphorous coating. When electron beam excitethe phosphorus, they glow. !he color of the screen depends on the electron which one excitesthe phosphorus then they glow red , green or blue. !he three beams should converge for eachpoint on the screen so that each pixel is a combination of the three colors.

!he )B! monitor displays color picture or image by using a combination of phosphorous thatemits di$erent colored light. ;y combining the emitted light from the di$erent phosphorous, arange of colors can be generated. !wo basic techni+ues for producing color display with )B!are%

-. ;eam penetration method%0. 3hadow&mask 6ethod. *Boster

'eam pe%etrato% metho(: !his techni+ue is used in random&scan display systems. !wo layers of phosphor *red andgreen are coated on to the inside of the )B! screen, the displayed colors depends on how farthe electron beam penetrates into the phosphor layers. A slow electron beam excites only theouter red layer. A high speed electron beam excites the inner green layer and averaged speedelectron beam at the intermediate speed that produces combination of red and green color*lights as two additional colors yellow and orange. !he speed of the electron is controlled bythe beam acceleration voltage. t is an in expansive techni+ue but only four colors arepossible. !he +uality of picture is not good than other method.

The mert! a%( (emert! o> the Pe%etrato% tech%Bue! are a! >oo!:

• t is an inexpensive techni+ue

• t has only four colors

• !he +uality of the picture is not good when it is compared to other techni+ues

• t can display color scans in monitors

• Coor limitation etc.

Sha(o/ma!) Metho( !his techni+ue is used in raster&scan display systems. !he techni+ue produces a much widerrange of colors than beam penetration method. !he three types of phosphorus dots is coated

in each pixel that is red, green and blue. Lust behind the )B! screen shadow mask grid *metalgrid is placed whose number is same as a number of pixel. !hree electron guns are adjustedfor each phosphorous. 8ne phosphor dot emits red light , another emits a green light and thethird emits blue light. !his type of )B! has three electron guns , one for each color dots. !heelectron beams are detected and focus on the shadow mask hole. !he Cassed from the holeactivate the dot triangle and produce the color spot on the screen. !he color of pixel iscontrolled by light of intensity. ;y combing three color,-J million color can be obtained. Ior true color each pixel has 0@bits in the frame bu$er. !hecolor we see on the screen depends on the amount of excitations of the red,green and bluephosphor.



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Advantages of CR 'onitor:

• t has wider viewing angle.

• t is cheaper and durable.

• t gives sharp and crisp image.

t has adjustable resolution.

"isadvantages of CR 'onitor:

• t is bulky and heavy.

• t consumes high electricity power.

• !he screen may Kicker causing eyestrain.

• !akes more space to place it.

. 5LAT/ PA#EL DISPLA4:Although most graphics monitors are still constructed with )B!s, other technologies areemerging that may soon replace )B! monitors. !he term Ilat&panel display refers to a class of video devices that have reduced volume, weight, and power re+uirements compared to a )B!.A signi'cant feature of Kat&panel displays is that they are thinner than )B!s, and we can hangthem on walls or wear them on our wrists also. 3ince we can even write on some Kat&panel

displays, they will soon be available as pocket notepads. )urrent uses for Kat&panel displaysinclude small ! monitors, calculators, pocket video games, laptop computers, armrestviewing of movies on airlines, as advertisement boards in elevators, and as graphics displaysin applications re+uiring rugged, portable monitors. At present ,Kat&panel displays arecommonly used in small systems and in special&purpose systems.We can separate Kat&panel displays into two categories% Em!!$e (!pa3! and #o%/em!!$e (!pa3!. !he emissive displays *or emitters are devices that convert electricalenergy into light energy. Clasma panels, thin&'lm electroluminescent displays, and :ight&emitting diodes are examples of emissive displays. Ilat )B!s have also been devised, in whichelectron beams arts accelerated parallel to the screen, then deKected >5 to the screen. ;utKat )B!s have not proved to be as successful as other emissive devices. 9on&emissive displays*or non&emitters use optical e$ects to convert sunlight or light from any other source into

graphics pattern. !he most important example of a non&emissive Kat&panel display is a li+uid&crystal device.

LBu( Cr3!ta D!pa3 9LCD Mo%tor::)4 monitor is the type of Ilat Canel display like Electroluminescent *E: and Clasma 4isplay.:)4 is the most common Kat panel monitor. t creates images with a special kind of li+uid thatis normally transparent but becomes opa+ue when charged with electricity. !he li+uidcrystalline material is sandwiched between two glass or plastic plates. !he front plate istransparent and the back is reKective. :)4 is lighter in weight, not bulky but expensivecompared to )B! monitors. t consumes low voltage and power consumption. !he user shouldsit in front to monitor, if she Mhe sits with angle, contents are not visible. t does not emit lightas )B!, so there is no enough contrast between the image and the background. t is widely

used in laptops, computers, digital cameras, digital clocks, digital watches, microwave ovens,)4 players etc.

Advantages of (C" )onitor:

• Ilat 3creen

• :ightweight



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• :ess electricity power consumption.

• Avoids eye strain problem.

• !akes less space.

"isadvantages of (C" )onitor:

• )onsists smaller viewing angle.

• mages are less sharp.

• Besolution is normally set.

Lght Emtt%g Do(e 9LED Mo%tor::ight Emitting 4iode is also an advance technology consisting monitor. !his is the type of Emissive Ilat&Canel display. :E4 is a semiconductor light source system and this system at'rst introduced as a practical electronic component in ->?0. !his is used the Emissive

!echnology in which electrical energy is converted into light. !his technology is mostcommonly found in calculators, retail checkout counters, large digital watches and automaticteller devices. !hese are the devices which converts the electrical signals into light. :E4displays use backlights designed with an array of lights. !he lights are evenly arranged on theback of the panel or positioned on the screen edges. :E4 monitors are expensive atapproximately 0R more than :)4 monitor.t contains a matrix of diodes those are arrangedon the screen as the pixel position. And the picture de'nition is stored in the Befresh bu$er

and when information is read from the refresh bu$er and then it is converted into the voltagelevels and it is applied to diodes which produce the light pattern in the display.

Advantages of (E" 'onitors:t has long life.

Avoids eye strain problem.

• Ilat 3creen

• :ightweight

• :ess electricity power consumption.

• t has wider viewing angle.

Ga! Pa!ma D!pa3:Gas Clasma 4isplay is a type of Ilat display screen. t is also named as a Ilat /panel display. tis used in some portable computers and widely used for large ! displays *typically above 1J&inch.!he major components of plasma displays are% Iresnel lens, 8ptional deKection coils,Electrostatic deKectors, 8ptional deKectors and cathode. t produces very sharp monochromeimages.Gas Clasma display is like a neon bulb, in which the display uses a gas that emits lightin the presence of an electric current. !hat is, the technology uses predominantly neon gasand electrodes above and below the gas. When, electric current passes between theelectrodes, the gas glows. t works by sandwiching neon or xenon gas between two plates.Each plate is coated with a conductive print. !he print on one plate contains verticalconductive lines and the other plate has hori(ontal lines. When electronic current is passedthrough a hori(ontal and vertical line, the gas at the intersection glows, creating a point of

light , or pixel.

Advantages of Gas#*las'a "ispla+:

• An image produced is colorful and bright.



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• !he scenesMimages look natural.

• :arger viewing angle.

• Avoids eye strain and tired problem.

• Befreshing is not re+uired.

• :ess bulky than a )B!.

"isadvantages of Gas#*las'a "ispla+:

• Expensive• =igh power consumption.

• !akes more place.

• Coor resolution of up to ? d.p.i.

4i$erentiate plasma panel display and thin 'lm electro luminescent as followed%n plasmapanel display, the region between two glass plates is 'lled with neon gas. n thin 'lm electroluminescent display, the region between two glassesplates are 'lled with phosphor, such as(inc sulphide doped with manganese.

,. GRAPHICS DISPLA4 S4STEM

I. RASTER/SCA# DISPLA4 S4STEM !he raster graphics developed in early J2s. !he term "Baster&scan# is used for raster graphicwhich is the pattern of image storage and transmission that used in most computer bitmapimage systems. Baster 3can display system is based on the !elevision technology. !he mostcommon type of graphics monitor employ in a )B!s is the Baster&3can display system. n thissystem, electron beam swaps across the screen one row at a time from top to bottom. As theelectron beam moves across each row, the beam intensity is turned on and o$ to create apattern of illuminated spots. Cicture de'nitions are stored in refresh bu$er or frame bu$erwhich holds the setup intensity values for the entire screen point i.e. pixel. 3tored intensityvalues are then retrieved from the refresh bu$er and painted on the screen one row *scan lineat a time.

!he capability of a raster&scan system to store intensity information for each screen pointmakes it well suited for the realistic display of scenes containing subtle shading and colorpatterns. n monochrome monitor *black&and&white system frame bu$er consists of one bit

per each pixel and for color monitor frame bu$er consists of 0@ bits for each pixel. !he refreshrate for this system is at the rate of ? to frame per second. i.e refresh rate are describedin units of cycle per second. t is well suited for realistic scenes containing shading and colorpattern. =ome television sets and printers are examples of other systems using raster&scanmethods.



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nteractive Baster Graphics systems typically employ several processing units. n addition tothe )C , a special purpose processor *ideo controller M display controller is used to controlthe operation of the display device. n addition to the ideo controller other processor andaccelerator can be employed to implement various graphics operations.

Function of 'ain co'ponents of Raster#Scan displa+ s+ste':S3!tem Memor3: !he system memory holds data and those programs which execute on )C% the applicationprograms, graphics package and operating system.D!pa3 Proce!!or Memor3: t holds data and the programs which perform scan conversion and raster operations.5rame 'uer:Cicture de'nition is stored in a memory is called Irame bu$er. t is sometimes also referred asrefresh bu$er. !his memory area holds the set of intensity values for all the screen points.3tored intensity values are then retrieved from the frame bu$er painted on the screen point*pixel one row at a time.;(eo Co%troer:

ideo controller is also called ideo Adapter. !he electronic components re+uired to generatea video signal that is sent to the video display through a cable. !he video controller is usuallylocated either on the computer5s main system board or on an expansion board, but it can alsobe part of a terminal. ideo controller is used to control the operation of the display device.Irame bu$er can be anywhere in the system memory and the video controller accesses theframe bu$er to refresh the screen. ideo controller also contains a look up table instead of controlling )B! beam intensity directly. !his provides a fast mechanism for changing screenintensity values.!o perform the basic refresh operation of the video controller two registers areused to store the coordinates of the screen pixels. nitially the F&register is set to *(ero and

N register is set to N&max *i.e. FS and NSymax. n some personal computers, the coordinateorigin is referenced at the upper left corner of the screen. t provides direct access to theframe/bu$er memory. Irame bu$er may a 'xed area of the system memory or may be special

memory of display processor which is used to store the picture de'nition. ideo controller canbe performed other operations like to mix the frame&bu$er image with an input image from acamera or other devices.

Where the video controller is used?A special purpose processor, which is used to control the operation of the display device, isknown as video controller or display controller. A 'xed area of the system is reserved for theframe bu$er, and the video controller is given direct access to the frame bu$er memory.

D!pa3 Proce!!or:4isplay Crocessor is referred as graphics controller or display coprocessor. !he purpose of thedisplay processor is to free the )C from the graphics chores. n addition to the systemmemory, a separate display processor memory area can also be provided. !he main task of the display processor is to digiti(e a picture de'nition *called scan converting given to anapplications program into a set of Cixel/intensity values for storing them in the refresh bu$er.A display processor performs the additional functions like generating various line styles*dotted, dashed or solid, displaying color areas, performing certain transformations andmanipulation of displayed object.



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:ines and other geometric objects are converted into set of discrete intensity points.)haracters can be de'ned with rectangular grids, or they can be de'ned with curved outlines.

!o reduce the memory space re+uired to store the image information, each scan line arestored as a set of integer pairs. 8ne number of each pair indicates an intensity value, and thesecond number speci'es number of adjacent pixels the scan line that is also having sameintensity. !his techni+ue is called run&length encoding. 3ophisticated display processor canperform complex operations like% storing list of display instructions by using local memory,clipping and window&to&viewport transformations, 14 geometric transformations and clipping,local segment storage or display list storage etc.

Advantages of Raster#scan s+ste':

• Baster&3can systems are designed for display realistic shaded scenes.

• Baster&3can systems consist advanced devices like video control, coprocessors etc.

• Baster scan is easier and less expensive to implement than in random scan system.

• 8ne major advantages of raster graphics over vector graphics includes the ability to

display areas 'lled with solid colors or patterns.

"isadvantages of Raster#scan s+ste':

• 6ajor disadvantage of raster system compared to vector system is the discrete natureof the pixel representation. !his happens due to scan&conversion of end points*vertices into their component pixels in frame bu$er.

II. RA#DOM/SCA# DISPLA4 S4STEMA random scan display system is also called vector, stroke writing or calligraphic systemwhere electron beam is directed only to the part of the screen where the picture is to be

drawn. n a random scan display, an image on the screen is drawn with one line at time. Anapplication program is input and stored in the system memory along with the graphicpackage. Graphics commands in the application program are translated by the graphicpackage in to a display 'le *sometimes referred as display list or display program or refreshbu$er stored in the system memory. !his display 'le is then accessed by the displayprocessor to refresh the screen. 3ometimes the display processor in a random scan is referredto as a display processing unit or a graphics controller. !he bu$er stores the computer producedisplay list or display program which contains points and line plotting commands with *x , yand end point co&ordinates as well as character plotting commands. !he commands forplotting points lines and characters are interpreted by the display processor.



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!he main principal of the random scan system is that the beam is deKected form end point toend point as detected by arbitrary order of the display commands term as random scan.Bandom scan display system is mostly used for line drawing applications and can not displayrealistic shaded scenes.

t has higher resolution t produces smooth line drawing because the )B! beam directly followsthe line path de'nitions that are stored in the form of line drawing commands. Befresh rate on

a random scan system depends on the number of lines to be displayed. Bandom scan displayis design to draw all the component lines of pictures 1 to ? times per seconds. =igh&+ualityraster scan systems are capable of handling approximately -, "short" lines at thisrefresh rate. A )B! beam in this system is adjusted in such a way that electron beam only hitsthe spot where the graphics is to be drawn. !hus the refresh rate in this system depends uponthe number of lines to be displayed. A Cen plotter operates in a similar way and is an exampleof a random&scan system using hard&copy device.

Advantages of Rando'#Scan S+ste':-. ery high resolution, limited only by monitor.0. Easy animation, just draw at di$erent positions.1. Be+uires little memory *just enough to hold the display program

"isadvantages of Rando'#Scan S+ste':

-. Be+uires intelligent electron beam i.e. processor controlled.0. When the number of command in the bu$er goes high the system take long time to

process and draw pictures.1. )annot apply shading features.

DI55ERE#CE 'ETEE# RA#DOM/SCA# DISPLA4 A#D RASTER/SCA#DISPLA4 Sr. RA#DOM/SCA# DISPLA4 Sr

.RASTER/SCA# DISPLA4

-. t has high resolutions since the picturede'nition is stored as a set of linedrawing commands and not as a set of

intensity values.

-. t has less resolution than Bandom&scandisplay system.

0.

t produced smooth lines as the electronbeam directly follows the line path.

0. t produced the (ig&(ag lines as theplotted values are discrete.



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1.

Bealism is diQcult to achieve in thissystem.

1.

=igh degree realism is achieved in picturewith the aid of advanced shading andhidden surface techni+ue.

@.

Bandom&scan systems are generallycostlier.

@.

4ecreasing memory costs have maderaster systems popular. Baster scan iseasier and less expensive to implement

than in random scan system.7. A vector system can draw continuous,smooth line *curves from any point onthe )B! face to other.

7. !he raster system displays lines *curvesmathematically using various algorithmscausing problems of Djaggering#orDstaircasing#.

?. Bandom 3can 3ystem *devices speciallydesigned for :ine drawing applications.

?. Baster 3can 3ystem *devices speciallydesigned for realistic shaded scene.

J. Befresh rate of Bandom 3can 3ystemdepends on the numbers of the lines tobe displayed.

J. Befresh rate of Baster 3can 3ystemdepends on the numbers of pixelsscanned per second.

. Cicture de'nition is stored as a set of line drawing instructions.

. Cicture de'nition is stored as a set of intensity values for all screen points.

Some term! u!e( % th! chapter: PFe:

Cixel is sometimes referred as Cel which stands for Cixel Element. Each screen point of the monitor or display system is known as a Cixel. Cixels are the basic building blocks of all the images.

Sca% co%$er!o%:A major task of the display processor is digiti(ing a picture de'nition given in an

application program into a set of pixel&intensity values for storage in the frame bu$er. !his digiti(ation process is called scan conversion.

Per!!te%ce: !his term persistence is related to the )B!. A Chosphor2s persistence is de'ned as the

time from the removal of excitation to the movement when phosphorescence hasdecayed to - percent of the initial light output. t ranges from - to ? microseconds.

!his light output decays exponentially with line. :ower persistence phosphors re+uirehigher refresh rates to maintain a picture on the screen without Kicker. A phosphor withlow persistence is useful for animation and a phosphor with high persistence is useful fordisplaying highly complex, static pictures. t ranges from -&? microseconds. 3o, persistence

is the time it takes the emitted light from the screen to decay one tenth of its originalintensity is called as persistence.

Re>re!h rate: !his term Befresh rate is also related to the )B!. t is the number of times a display2simage is repainted or refreshed per second. !he refresh rate is expressed in hert(. Arefresh of J7 means the image is refreshed J7 times in a second. !he refresh rate foreach display devices depends on the video card used. Nou can change the refresh rate inthe display properties. =owever if you change the refresh rate to a setting that thedisplay or video card cannot support , the display goes blank or the image becomesdistorted. t is recommended to consult the display and video card manuals beforechanging the setting to determine the supported refresh rates.

Re!outo%: !he maximum number of points that can be displayed without overlap on a )B! isreferred to as the resolution. A more precise de'nition of resolution is the number of points per centimetre that can be plotted hori(ontally and vertically, although it oftensimply stated as the total number of points in each direction. !he resolution of a )B! isdependent on the type phosphor, the intensity to be displayed, and the focusing and



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deKection systems. !ypical resolution on high /+uality systems is -0 by -0@, withhigher resolution available on many systems.

A!pect rato: !his term Befresh rate is also related to the )B!. !his is another property of the video

monitors. !his number gives the ratio of vertical points to hori(ontal points necessary toproduce e+ual&length lines in both directions on the screen. 3ometimes aspect ratio is

stated in the terms of the ratio of hori(ontal to vertical points. An aspect ratio of T meansthat a vertical line plotted with three points has the same length as a hori(ontal line plotted

with four points. 3o, the aspect ratio is the ratio of vertical points to the hori(ontalpoints necessary to produce length of lines in both directions of the screen.

5rame ?uer!:Cicture de'nition is stored in a memory area called frame bu$er or refresh bu$er. A

frame bu$er is a large, contiguous piece of computer memory. At a minimum, there is onememory bit for each pixel *picture element in the raster. !his amount of memory iscalled a bit plane or a bit map. 3ome graphics systems have a frame bu$er memorydistinct from main memory. !he current trend is to have the frame bu$er accessible tothe central processing unit *)C of the main computer. !he number of rows in the framebu$er array e+uals the number of raster lines on the display screen. !he number of

columns in this array e+uals the number of pixels on each raster line.

hat ! ra!ter@ato%

!he process of determining the appropriate pixels for representing picture orgraphics object is known as rasteri(ation.

hat ! ame%t

n the )B!, heat is applied to the cathode by directing a current through acoil of wire, is called 'lament.


U#IT: GRAPHICS ALGORITHM


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U#IT: , GRAPHICS DIMENSIONS


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1. To /Dme%!o%a Geometrc Tra%!>ormato%!:

• !ranslation

• Botation

• 3calling

• )omposite !ransformation

• =omogeneous )o&ordinate 3ystem

"D TRA#S5ORMATIO#: !ransformation is the backbone of )omputer graphics which enables us to manipulate theshape, si(e and location of the object. 04 !ransformation is the process of manipulating thecoordinates or position, orientation and si(e of any object. !his is also called geometrictransformation. All of these transformations can be eQciently and succinctly handled byusing some simple matrix representations.n all the )omputer Graphics there is facility to move an object, rotate an object and translatean object. 04 or !wo 4imensional is that which provides these rotations those are based onmathematical forms and there are two types of movements of object. Iirst those are alsoknown as geometric transformation and co&ordinate transformation. Geometrictransformations have numerous applications in geometric modelling, e.g., manipulation of

si(e, shape, and location of an object.n this object is moved on the coordinate system or background. n other words when anobject moves to his axis while the background is 'xed for example when a car moves onstable road this is called as Geometric 3ystem when object is 'xed and background movesthen it is called as )oordinate 3ystem. Ior example in many movies we can see the car whichis running fast on the road this is not truth. n this instead moving a car a background moveacross the car. n )A4, transformation is also used to generate surfaces and solids bysweeping curves and surfaces, respectively. !he term Dsweeping# refers to parametrictransformations, which are utili(ed to generate surfaces and solids. When we sweep a curve, itis transformed through several positions along or around an axis, generating a surface

There are to t3pe! o> tra%!>ormato%!%

Mo(e%g Tra%!>ormato%% !his transformation alters the coordinate values of the object. ;asic 8perations arescaling, translation, rotation and, combination of one or more of these basictransformations. Examples of these transformations can be easily found in anycommercial )A4 software. Ior instance, Auto)A4 uses 3)A:E, 68E, and B8!A!Ecommands for scaling, translation, and rotation transformations, respectively.

;!ua Tra%!>ormato%%n this transformation there is no change in either the geometry or the coordinates of the object. A copy of the object is placed at the desired sight, without changing thecoordinate values of the object. n Auto)A4, the H886 and CA9 commands are good

examples of visual transformation.

Calculations see in handwritten notes:



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". To/Dme%!o%a O?ect to !cree% ;e%g:9%(o to $eport coor(%ate tra%!>ormato% o%3:

"/Dme%!o%a ;e%g Ppe%e:A graphical package allows a user to specify which part of the de'ned picture is to bedisplayed and where that part is to be placed on the display device. Any convenient )artesiancoordinate system< referred to as the world co ordinate reference frame can be used to de'ne

the picture. Ior a 0&4 picture, a view is selected by specifying a subarea of the total picturearea. A user can select single area for displaying or several areas could be selected forsimultaneous display. !he picture parts within the selected areas are then mapped ontospeci'ed areas of the device co&ordinates. When the multiple view areas are selected, theseareas can be placed in separate display locations or some areas could be inserted into other,larger display area. !ransformations from world to device coordinates involve translationrotation and scaling operations, as well as procedures for deleting those parts of the picturethat are outside the limits of a selected display area. A world co&ordinate area selected fordisplay is called a window. An area on the display device to which a window is mapped iscalled a view port. !he window de'nes what is to be viewed. !he viewport de'nes where it isto be displayed. 8ften, windows and viewports are rectangles in standard positions, if therectangle edges are parallel to the co&ordinate axis. D!he mapping of a port of a world co&

ordinate scene to a device co&ordinate is referred to as viewing transformation.# 3ometimes,the 04 viewing transformation is simply referred to as the window / to / viewporttransformation or the windowing transformation.

Iigure is shown below to illustrate the mapping of picture selections that fall within arectangular window onto a designated rectangular viewpoint.

Figure: A viewing transformation using standard rectangles for the window and viewpoint.

Step! to ?e >ooe( >or %(o to $epo%t tra%!>ormato%! area:

U Generate world co&ordinateU )onvert world co&ordinate to view co&ordinate.U 6ap the view co&ordinate to normali(ed viewing coordinate.U 6ap the normali(ed viewing co&ordinate to device coordinate system.



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"D I#DO TO ;IE PORT MAPPI#G: !he world co&ordinate selected for display is called window. !he area on the display device towhich window is mapped is called viewport. 3o, window de'nes what is to be viewport

de'nes where it is to be displayed. !he mapping of part of world co&ordinate scene to deviceco&ordinate is called viewing transformation or window&to&viewport transformation.%(o J to J $eport tra%!>ormato% ca% ?e eFpa%e( a! >oo%g term!:

U )hoose the world co&ordinate in a rectangle.U !ransform it to origin.U 3cale it with appropriate value.

!ransform it to the relative position in viewport.

• 3tep -% ! *&xwmin, &ywmin

• 3tep%0% 3 *sx, sy

• 3tep%1% !*xvmin, yvmin

V 9et transformation,

!wv S ! *xvmin, yvmin. 3*sx, sy.!*&xwmin, &ywmin

. Cpp%g a%( Cohe% Suthera%( cpp%g Agorthm:

CLIPPI#G:)lipping is the procedure that identi'es these portions of the picture that are either inside oroutside of the speci'ed region of span. Applications of clipping include extracting part of adetained scene for viewing ,identifying visible surfaces in three&dimensional views, antialiasingline segments or object boundaries, creating objects using solid&modelling procedures,displaying a multi&window environment , and drawing and painting operations that allow partsof a picture to be selected for copying, moving, erasing, or duplicating.

4epending on the application, the clip window can be a general polygon or it can even havecurved boundaries. We 'rst consider clipping methods using rectangular clip regions then wediscuss methods for other clip&region shapes.Appcato%! o> cpp%g:

-. Extracting part parts of a de'ned scene for viewing.



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0. dentifying visible surface in 1&4imensional views.1. 4isplaying a multi&window environment.@. 4rawing and painting operation that allows parts of a picture to be selected for copying,

moving, erasing, or duplicating.

T3pe! o> cpp%g::ine and polygon clipping routines are standard components of graphics packages, but many

packages accommodate curved objects, particularly spline curves and conics, such as circlesand ellipses. Another way to handle curved objects is to approximate them with straight&linesegments and apply the line& or polygon clipping procedure.

• Coint )lipping

• :ine )lipping *straight&line segments

• Area )lipping *polygons

• )urve )lipping

• !ext )lipping

Po%t cpp%g:Assuming that the clip window is a rectangle in standard position, we save a point C S ,- 3for display if the following ine+ualities are satis'ed%

where the edges of the clip window

can be either theworld&coordinate window boundaries or view portboundaries. f any one of these four ine+ualities is not

satis'ed, the point is clipped *not saved for display. Although point clipping is applied lessoften than line or polygon clipping, some applications may re+uire a point clipping procedure.Ior example, point clipping can be applied to scenes involving explosions or sea foam that aremodelled with particles *points distributed in some region of the scene.

LI#E CLIPPI#G:Iigure shown below illustrates possible relationships between line positions and a standardrectangular clipping region. A line clipping procedure involves several parts. Iirst, we can testa given line segment to determine whether it lies completely inside the clipping window. f itdoes not, we try to determine whether it lies completely outside the window. Iinally, if wecannot identify a line as completely inside or completely outside, we must performintersection calculations with one or more clipping boundaries. We process lines through the"inside&outside55 test by checking the line endpoints.



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Cohe% Suthera%( %e cpp%g:)ohen 3utherland line clipping is an oldest and most popular algorithm that speeds up theprocessing of the line segments by performing initial tests that reduce the number of intersections that must be calculated. n this method, every line endpoint is assigned a four

digit binary code which is called as region code that identi'es the location of the point relativeto the boundaries. Begions are set up in reference to the boundaries as shown in the 'gurebelow. Each bit position in the region code is used to indicate one of the four relativecoordinate p

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