1. Overview of Graphic Systems
Dr. Aree Ali Mohammed
Assistant Professor
3rd Stage
University of Sulaimani – Computer Science Dept.

2. Computer Graphics and Vision
Computer graphics are created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware.
Computer vision is a field that includes methods for acquiring, processing, analyzing, and understanding images.

3. What is Interactive Computer Graphics?
User controls content, structure, and appearance of objects and their displayed images via rapid visual feedback
Basic components of an interactive graphics system
input (e.g., mouse, tablet and stylus, multi-touch…)
processing (and storage)
display/output (e.g., screen, paper-based printer, video recorder…)

4. Conceptual Framework for Interactive Graphics
System/
GPU
Application
Model / database
Software
Hardware
Application
program
Graphics
Library
- Graphics Library - Between application and display hardware there is graphics library / API. - Application Program - An application program maps all application objects to images by invoking graphics. - Graphics System – An interface that interacts between Graphics library and Hardware. - Modifications to images are the result of user interaction.

5. Graphics System Video Display Devices
Refresh Cathode-Ray Tubes (CRTs)
Raster-Scan Displays
Random-Scan Displays
Color CRT Monitors
Flat-Panel Displays
Graphics Workstations and Viewing Systems
Input Devices
Hard-copy Devices

6. Video Display Devices
The primary output device in a graphics system is a video monitor. It is based on the standard cathode-ray tube (CRT) design.
CRT :
A beam of electrons, emitted by an electron gun, passed through focusing and deflection systems that direct the beam toward specified positions on the phosphor-coated screen
 The phosphor emits a small spot of light at each position contacted by the electron beam
 The light emitted by the phosphor fades very rapidly
 the screen picture is maintained by directing the electron beam repeatedly over the same screen points
 This type of screen called refresh CRT and the frequency is called refresh rate

7. Video Display Devices (CRT)

8. Video Display Devices (CRT)

9. Raster – Scan Systems
 Most common type used in CRT, Based on television technology
 The electronic beam is swept across screen, one row at a time, from top to bottom, each row is referred to as a scan line
 As the electronic beam moves across a scan line, the beam intensity is turned on or off (or set to sum an intermediate value)
 Picture definition is stored in a memory area called the refresh buffer or frame buffer

10. Architecture of Raster Scan

11. Architecture of Raster Scan

12. Architecture of Vector Scan

13. 
Random – Scan Systems

14. Random – Scan Systems  Used in architectural and engineering layouts
 Problem: no shading
 Random-scan displays produce smooth lines
 Raster-scan displays produce jagged lines

15. Color CRT Monitors  Use RGB color model  Produce more colors
 Each pixel composed of three
phosphor color dots (RGB)
 3 electronic guns are used

16. Flat-Panel displays  Reduce volume, weight, and power  Thinner
Plasma:
Two glass plates with mixture of gases
(neon)
 Vertical conducting ribbons in one glass and horizontal in another

17. Liquid Crystal Display LCD
Produce pictures by passing polarized light through liquid crystal material that can be aligned to either block or transmit the light
Graphics Workstations and Viewing Systems
Graphics systems range from small general-purpose computer systems with graphics capabilities to sophisticated full color systems that are designed specifically for graphics applications

18. Input and Hard Copy Devices
Input Devices
Keyboard and mouser
|Trackball
Joysticks
Data glove
Voice system
early light pens to modern mice
data tablet
touch sensitive screens
3D input devices (spaceballs etc.)
Button and dial boxes
Output Devices
Printers
Pen plotter

19. Input and Hard Copy Devices
Input Devices
Keyboard - good for text, awkward for graphics.
Mouse - popular and convenient for graphics.
Data tablet - good for accurate digitalization of existing hard copies as vector sets.
Scanner - - good for digitalization of existing hard copies as pixel sets.
Light pen - usually not as convenient as a mouse.
Touch screen - more useful for menu selection than for graphics.
Joystick - useful for interactive graphics (games).

20. Output Device Raster Devices Vector Devices
CRT - the common display device for personal computers.
LCD - A smaller, lighter, lower power replacement for the CRT.
LED - A smaller, lighter, lower power replacement for the CRT.
Plasma screens - a more expensive but brighter alternative to LCDs.
Printers - today's printers are good for both text and graphics
Vector Devices
Plotters - good for vector graphics.
Oscilloscope - an early vector graphics output device

21. Review Questions and Discussion
What do you mean by rasterization?
Compare raster and vector scan displays.
Write a short note on
a. Flat panel display
b. Plasma panel display
4. What do you understand by the terms raster scan and
refresh rate?
5. Define aspect ratio.

22. Application of Computer Graphics
 Graphs and Charts
 Computer Aided Design CAD
 Virtual-Reality Environments
 Data Visualization
 Entertainment
 Image Processing
 Graphical User Interfaces GUI
 Advertisement
 Games

23. Application of Computer Graphics

25. Graphics Software
In computer graphics, graphics software or image editing software is a program or collection of programs that enable a person to manipulate visual images on a computer.
Raster:
Vector:

26. Reading List “Computer Graphics with OpenGL” , chapter 1, 2.
Raster versus Vector