UNIT 1: GRAPHICS SYSTEMS AND OUTPUT PRIMITIVES

Introduction

• Definition of Computer Graphics

  • Generation of pictures via computing

  • Modelling: creation, manipulation, storage of geometric objects

  • Rendering: transformations, shading, illumination, animation

  • Applications span diverse fields including science, engineering, medicine, business, art, entertainment, etc.

History of Computer Graphics

• 1950’s: First computer-driven CRT display for simple graphics

• 1950: Ben Laposky created the first graphic images using an oscilloscope

• 1960’s: Introduction of modern interactive graphics and vector graphics

• 1960: William Fetter coins "computer graphics" for new design methods

• 1980’s: Growth of raster graphics in personal computers

• 1990’s: VGA and SVGA enabled photorealistic images and 3D renderings

Applications of Computer Graphics

• Main Applications:

  • Computer-Aided Design (CAD)

  • Presentation Graphics

  • Computer Art

  • Entertainment

  • Education and Training

  • Information Visualization

  • Image Processing

  • Information Graphics

  • Virtual Reality (VR)

Detailed Applications

1. Computer-Aided Design:

   • Used for designing buildings, cars, aircraft, etc.

   • Provides minute details and accuracy.

2. Presentation Graphics:

   • Prepares reports and summarizes data.

   • Tools for creating graphs and charts.

3. Computer Art:

   • Enables creation of animations and fine art.

   • Packages for designing shapes and motions.

4. Entertainment:

   • Utilized extensively in movies, games, and animations.

5. Education & Training:

   • Generates models for complex concepts, enhancing understanding.

6. Information Visualization:

   • Visualizes data to aid decision making.

7. Image Processing:

   • Edits photographs for various applications.

8. Information Graphics:

   • Represents data visually for quick understanding.

9. Virtual Reality:

   • Simulates real-world or imaginary environments.

Computer Graphics Classification

1. By Type of Object:

   • Dimensionality such as 2D or 3D.

2. By Interaction Type:

   • Offline vs. Interactive plotting.

3. By Role of Picture:

   • The end product vs means to an end.

4. By Relationship Between Objects:

   • One picture vs a sequence or collection of objects.

Graphics Software

• Software enabling manipulation of visual images.

1. General Programming Packages:

   • High-level programming languages with graphics functions.

2. Special Purpose Packages:

   • Designed for non-programmers (e.g., Photoshop, CorelDRAW).

Working of Interactive Display

• Components:

  1. Frame Buffer

  2. Display Controller

  3. Monitor

• Frame Buffer: Stores image as intensity values.

• Display Controller: Controls display operations and refresh rates.

• Challenges with drawing pixels, including smooth curves, are addressed using algorithms.

Cathode Ray Tube (CRT)

• Functionality:

  • Produces images when an electron beam strikes a phosphor surface.

  • Requires frequent redrawing to maintain picture clarity.

CRT Components

1. Heating Metal/Filament

2. Cathode

3. Control Grid

4. Focusing System

5. Acceleration Anode

6. Deflection System

7. Phosphors used for color imagery and their advantages/disadvantages.

Factors Affecting CRT

1. Resolution

   • Higher resolution means better graphics quality.

2. Persistence

   • Impacts refresh rates and animation quality.

3. Addressability

   • Size and spacing of pixels affect image clarity.

4. Aspect Ratio

   • Maintains proportional length lines.

Raster Scan Display

• Most common graphics monitor technology.

1. Operates by scanning from top to bottom easch row at a time.

2. Refresh rates typically range between 60–80 frames per second.

3. Distinguishes between interlaced and non-interlaced scanning methods.

Random Scan Display

• Electron beam directed only to areas requiring drawing.

1. Produces smooth line drawings, high resolution, but cannot display shades.

Color CRT Monitors

• Two methods for producing color displays:

1. Beam Penetration Method:

   • Limited to four colors; low image quality.

2. Shadow-Mask Method:

   • Produces a wider range of colors and is commonly used in TVs.

Other Display Technologies

• Direct View Storage Tube (DVST):

  • Remembers images displayed but not suitable for fast graphics.

• Flat Panel Display:

  • Reduces volume and power consumption compared to CRTs.

  • Emissive (light-emitting) and non-emissive types.

• Plasma Panel:

  • Uses gas discharge for bright, clear images.

• LCD (Liquid Crystal Display):

  • Produces images using light-polarization and lacks contrast.

Display Processors

• Essential for converting input into viewable images.

• Types:

  1. Raster-Scan Display Processor:

     • Incorporates a control processing unit for managing display.

  2. Random-Scan Display Processor:

     • Translates graphics commands from an application into screen images.

Instruction Set & Color Mapping

• Ensures consistent refreshing for flicker-free displays.

• Color models:

  1. RGB Model:

     • Utilizes red, green, and blue for color representation.

  2. CMY Model:

     • Subtraction process for color in printing.

  3. YIQ Model:

     • Used in TV broadcasting for efficient color transmission.

Mind Map for V SEM BCA ELECTIVE - COMPUTER GRAPHICS

Course Overview

• Total Teaching Hours: 48

UNIT 1: Graphics Systems and Output Primitives (12 Hours)

• Application of computer graphics

• Graphic software

• Video display devices

• Line and circle drawing methods

• Area filling techniques

UNIT 2: 2D-Transformation, Windowing and Clipping (12 Hours)

• Geometric transformation (Translation, Rotation, Scaling)

• Clipping process (Point, Line, Area)

• Window to viewport transformation

UNIT 3: 3D Graphics (12 Hours)

• 3D-Coordinate system

• Projections (Parallel, Perspective, Orthogonal)

• 3D-Transformations (Translation, Scaling) and Surface handling

UNIT 4: Graphical Input Devices and Techniques (12 Hours)

• Input Devices (Keyboard, Mouse, Joystick)

• Positioning techniques (Grid, Dynamic manipulation)

• Menus and Pointing by naming

History of Computer Graphics

• 1950’s to 1990’s

Applications of Computer Graphics

• CAD, Presentation Graphics, Computer Art

• Education & Training, Virtual Reality, Image Processing

Graphics Software

• General and Special Purpose Packages

Display Technologies

• CRT, Flat Panel, Plasma, LCD

• Color CRT Monitors and Methods

Display Processors

• Types: Raster-Scan and Random-Scan

Color Models

• RGB, CMY, YIQ