Overview of Graphic Systems. Dr. Aree Ali Mohammed Assistant Professor 2014-2015 3 rd Stage firstname.lastname@example.org. Computer Graphics and Vision.
Dr. Aree Ali Mohammed
University of Sulaimani – Computer Science Dept.
GPUConceptual Framework for Interactive Graphics
- 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.
Model / database
The primary output device in a graphics system is a video monitor. It is based on the standard cathode-ray tube (CRT) design.
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
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
Random – Scan Systems
Problem: no shading
Random-scan displays produce smooth lines
Raster-scan displays produce jagged lines
Random – Scan Systems
Produce more colors
Each pixel composed of three
phosphor color dots (RGB)
3 electronic guns are used
Color CRT Monitors
Two glass plates with mixture of gases
Vertical conducting ribbons in one glass and horizontal in another
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
Input and Hard Copy 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
Plotters - good for vector graphics.
Oscilloscope - an early vector graphics output device
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
5. Define aspect ratio.
Review Questions and Discussion
Graphs and Charts
Computer Aided Design CAD
Graphical User Interfaces GUI
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.