Overview of Graphic Systems

1. Overview of Graphic Systems Dr. Aree Ali Mohammed Assistant Professor 2014-2015 3rdStage aree.ali@univsul.edu.iq 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. Graphics System/ GPU Conceptual Framework for Interactive Graphics 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. Software Hardware Application Model / database

5. 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 Graphics System

6. 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 Video Display Devices

7. Video Display Devices (CRT)

8. Video Display Devices (CRT)

9.  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 Raster – Scan Systems

10. Architecture of Raster Scan

11. Architecture of Raster Scan

12. Architecture of Vector Scan

13.  Random – Scan Systems

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

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

16.  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 Flat-Panel displays

17. Produce pictures by passing polarized light through liquid crystal material that can be aligned to either block or transmit the light Liquid Crystal Display LCD 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 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 Input and Hard Copy Devices

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 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. 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. Review Questions and Discussion

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. 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: http://en.wikipedia.org/wiki/List_of_raster_graphics_editors#List Vector: http://en.wikipedia.org/wiki/List_of_vector_graphics_editors Graphics Software

26. Reading List • “Computer Graphics with OpenGL” , chapter 1, 2. • Raster versus Vector http://www.sketchpad.net/basics1.htm