introduction to computer graphics

Introduction To Computer Graphics

Prepared By:Er. Loknath Regmi

Computer Graphics

Course Overview


Introduction, History Application in different fields like CAD, schematic capture,

medicine, art etc. Hardware concepts 2-D and 3-D algorithms

Line drawing, viewing transformations, other transforms (scaling, rotation, translation)

Curve ModelingMathematics of generation of parametric cureve like Bazier,

Spline, Hermite 3D Object Modeling Visible Surface Detection and Surface Rendering Introduction to Animation Text Book

Computer Graphics C Version – Hearn & Baker

Computer Graphics


A sub-field of computer science which studies method for digitally synthesizing and manipulating visual content.

Are texts and sounds graphics ???No (wikipedia); but text??

Generally refers to (Ref: Wikipedia):Representation and manipulation of pictorial data

by computerVarious technologies used to create and

manipulate such pictorial dataThe image so produced

Image Processing Vs Computer Graphic Computer Graphics

a mathematical modeling deals about synthesis, manipulation,

processing, and storage of image of an object a complete package on generation and

modeling of graph deals about generation of math mathical model Image Processing not explain about synthesis of image explain manipulation and processing of existing

image use the mathematical model for processing of

image


History of Computer Graphics


Late 1950’s – Whirlwind computer (MIT) and SAGE (Semi Automatic Ground Environment); an automated control system to bombard enemy Used CRT and light pen for user interactive environment

1959 – TX-2 (MIT’s Lincoln Laboratory); first interactive interface computer system using light pen and bank switches

1960 – William Fetter Introduced phrase “Computer Graphics” Boeing man (Fetter called it First Man) for human figure simulation to

describe different user environment Mid 1960’s – MIT activities in computer graphics field promoted

early computer graphics industries like TRW, General Electric, IBM End 1960’s – organization, conferences, graphics standards and

publications 1969 – ACM initiated Special Interest Group In Graphics (SIGGRAPH)

History of Computer Graphics


1970’s – powerful PCs to draw basic and complex shapes

1980’s – artists and graphics designers preferred to use Macintosh and PCs

Late 1980’s – 3-D computer graphics with SGI (Silicon Graphics) computers

1990’s onwards – 3D graphics in gaming, multi media and animation, GUI

Applications Areas of CG


Display of InformationDesignSimulationComputer ArtEntertainment

Display of Information


Graphics for Scientific, Engineering, and Medical Data

Nebla Medical Image

Design


Graphics for Engineering and Architectural System

Design of Building, Automobile, Aircraft, Machine etc.

AutoCAD 2002 Interior Design

Simulation


Computer-Generated Models of Physical, Financial and Economic Systems for Educational Aids

Flight Simulator Mars Rover Simulator

Computer Art


Graphics for Artist

Metacreation Painter

Entertainment


Graphics for Movie, Game, VR etc.

Final Fantasy

Online Game

What’s Our Scope?


Not a Tutorial on Commercial Software3DMax, Maya, Photoshop, etc.

Not about Graphics Business3D online-game, E-commerce, etc.

Graphics = Algorithm for Visual SimulationImaging, Modeling, Rendering, Animation

Pixels The computer stores and displays pixels, or

picture elements.A pixel is the smallest addressable part of the

computer screen.A pixel is stored as a binary code representing a

colour.The code for a pixel can have between 1 and 32

bits of binary code.Here is the Photoshop logo at normal size.

Here it is enlarged 400% so that you can see the individual pixels.


Pixel DepthPixel Depth describes the number of bits used

to store each pixel. The greater the pixel depth, the more colours a

pixel can have.Colour graphics vary in realism depending on

resolution and pixel depth.The greater the pixel depth, the bigger the file.


Examples of Pixel Depth MonochromeMonochrome graphics have one-bit pixel depth.

(pure black or pure white)


Examples of Pixel Depth Gray-Scale

Gray-Scale graphics have more bit-depth(No colours besides black, white and grey)


Examples of Pixel Depth8 Bit Colour 8 bits per pixel provides 256 colour choices (Typical of the web - that’s why web graphics need some skilful preparation)


Examples of Pixel Depth 24 or 32 bits per pixel provides

thousands or millions of colour choices. (Typical of graphics and games software)


ResolutionResolution refers to the density of dots on the

screen or printed image and directly affects quality

The higher the resolution, the less jagged the image.

Resolution is measured in DPI (Dots per Inch)(The printing industry is largely unmetricated

and still uses inches because printing measures such as the Point (1 72nd of an inch) do not easily convert to metric units.)

The higher the resolution, the better the potential output.


Typical ResolutionsScreens generally operate at around 72-100

dpiPrinted images range from 300 to 2400 dpiResolution affects the file size of an image.The higher the resolution, the bigger the file. The visible resolution is limited to the

maximum possible on the output device (screen or printer).

No matter how high the resolution of a photograph, it will show at the resolution of your screen or printer.


File Types There are many kinds of graphics file

formats and this is a specialised area and a bit complicated.

Examples : bmp GIF JPEG TIFF PICT RawFor most applications involving

photographic images, use the JPEG file format (Joint Photographic Experts Group)

For graphics or paint type files use GIFs(Graphical Interchange Format)


JPEG The JPEG format can be used by most

applications and all browsersIt has very good compression algorithmsIt stores a good quality image in a

remarkably small file with little or no loss of quality

JPEG offers 10 quality levels with correspondingly smaller files and greater losses in quality


GIFYou should choose a GIF format instead of JPEG

whenYou have a graphic with only a few colours

such as a logo or iconYou want to create an image with some

transparent parts for a web pageYou want the smallest possible file size with

totally lossless compressionYou want to combine a few images together

into an animationYou want to save text as a graphic


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