Computer Graphics Notes
Subject Overview
Computer Graphics covers display devices and input hardware, scan conversion algorithms and area filling, 2D transformations and viewing/
Subject at a glance
4
Units
21
Topics
5
Credits
4
Infographics
Unit-wise Syllabus
4 units — open any unit for detailed topic-wise notes, diagrams and important exam questions
- Active and passive graphics
- applications
- input devices (light pens, graphic tablets, joysticks, trackball, digitizers, scanners)
- video display devices (CRT, raster/random scan, color CRT, DVST, flat-panel displays)
- color models (RGB, CMY)
- lookup tables
Draws by
Scanning every pixel row by row
Drawing lines directly
Picture stored as
Frame buffer of pixels
Display list of commands
Best for
Realistic images, shading
Line drawings
Example
Modern monitors
Early CAD displays
Study guide
This unit introduces graphics: active and passive graphics, applications, input devices, display devices (CRT, raster and random scan, flat panels) and colour models (RGB, CMY) and lookup tables. Compare raster scan with random scan displays.
- Process of scan conversion
- line/circle/ellipse scan conversion algorithms
- Bresenham's algorithms with derivations
- midpoint circle algorithm
- area filling and flood fill techniques
- character generation
Arithmetic
Floating point
Integer only
Speed
Slower
Faster
Accuracy
Rounding errors possible
More accurate
Uses
Simple to understand
Used in practice
Study guide
You study scan conversion of lines, circles and ellipses, Bresenham's algorithms with derivation, the midpoint circle algorithm, area filling, flood fill and character generation. Practise Bresenham's line algorithm by hand for one example.
- Cartesian and homogeneous coordinate systems
- geometric transformations (translation, scaling, rotation, reflection, shearing)
- 2D viewing transformation
- line/polygon/text clipping
- Cohen-Sutherland
- Sutherland-Hodgeman and Liang-Barsky clipping algorithms
Translation
x' = x + tx, y' = y + ty
Scaling
x' = sx · x, y' = sy · y
Rotation
x' = x cosθ − y sinθ, y' = x sinθ + y cosθ
Reflection about x-axis
x' = x, y' = −y
Shear in x
x' = x + shx · y
Study guide
You study coordinate systems, transformations (translation, scaling, rotation, reflection, shearing), 2D viewing and clipping: Cohen-Sutherland, Sutherland-Hodgeman and Liang-Barsky. Express each transformation as a matrix.
- 3D geometric transformations
- mathematics of parallel and perspective projections
- introduction to 3D viewing transformations and clipping
Projectors
Parallel to each other
Meet at a centre of projection
Size
Preserved regardless of distance
Distant objects look smaller
Looks
Less realistic
Realistic
Used for
Engineering drawings
Games, animation, architecture
Study guide
You study 3D transformations, parallel and perspective projections and an introduction to 3D viewing and clipping. Understand the difference between parallel and perspective projection visually.
Why Computer Graphics Matters
Computer graphics powers games, animation, simulation and design software, and the underlying mathematics also supports AR, VR and machine vision.
How to Prepare for Computer Graphics
- Practise line and circle algorithms and transformation matrices numerically.
- Write small graphics programs to see the algorithms work.
- Revise matrices from Mathematics-II.
Computer Graphics: Frequently Asked Questions
What is Bresenham's algorithm?
Bresenham's algorithm draws lines and circles on a raster display using only integer arithmetic to choose the closest pixels.
What is clipping?
Clipping removes the parts of a picture that lie outside a chosen window or region.