1. Overview of Graphics System
Graphics Hardware
Video Display Devices
CRT Basic
Type of CRT
Random-Scan Displays
Raster-Scan-Displays
Direct-View Storage Tubes(DVST)
Flat-Panel Displays
Others
Graphics Software

2. Video Display Devices
Cathode-Ray Tube(CRT)

3. CRT Basic (1/2) Phosphor refresh CRT Persistence
To maintain image, refresh electron beam repeatedly
Persistence
how long the phosphor continue to emit light after the election beam is removed.
defined as the time to takes 1/10 of its original intensity

4. CRT Basic (2/2) Resolution Aspect Ratio.
the maximum number of points that can be displayed without overlap on a CRT
simply the total number of points in horizontally and vertically
Aspect Ratio.
ratio of vertical points to horizontal points necessary to produce equal-length line in both direction
ex) 3/4 : length of 3points on vertical line = length of 4 points on
horizontal line

5. Type of CRT Ramdon-Scan Displays Raster-Scan Displays
Direct-View Storage Tubes (DVST)
Flat-Panel Displays

6. Random-Scan Display Vector Display (calligraphic display)
stored as a set of line-drawing commands in an area of memory (refresh display file, display list, frame buffer)
draw a picture one line at a time

7. Raster-Scan Displays (1/2)
Point plotting device : pixel or pel (picture Element)
picture info. for all the screen points is stored in separate Memory called Frame buffer (Refresh Buffer)
one row at a time (scan line) from top to bottom

8. Raster-Scan Displays (2/2)
Interlaced refresh procedure
used with slower refreshing rates
avoid flicker
provide adjacent scan lines

9. Vector vs Raster Displays
Rendering performance
VD: Sensitive to scene and object complexity
RD: Insensitive to scene and object complexity
Memory and processing requirement
VD: variable : depends on scene and object complexity
RD: Large but constant
Screen space aliasing
VG: None
RG: Frequent
Rendering of interior
VG: No (boundary only)
RG: Yes : Colored, Shaded and Textured surface

10. Raster Displays (Bitmap)
Intensity for each pixel depends on the size of frame buffer
ex) Black & White system
one bit per pixel is needed
the frame buffer is commonly called Bit map

11. Raster Displays (Pixmap)
With multiple bits per pixel, we can display gray-scale or color pictures
the frame buffer is commonly called pixmap
Size of Frame Buffer
when N=3, with 512 X 512
Size of Frame buffer = 3 X 29 X 29 = 3 X 218 = 768k

12. LUT (Look - Up - Table)
N bits per pixel = only 2N intensities are possible
To get more intensity use LUT
The LUT must contain 2N entries.
if the LUT consists of w bits then total 2w intensities are available
but only 2N intensities are available at a time
Advantage of LUT
1. Save Memory
2. Speed of color change

13. Color CRT Display Random-scan monitor Raster-scan monitor
Beam-penetration
Two layers of phosphor (red, green)
Raster-scan monitor
Called Shadow Mask method
System has 3 electron guns (R, G, B)
Each Gun is controlled by Frame buffer

14. True Color System

15. Raster Graphics System Architecture

16. DVST & Flat-Panel Displays
Direct-view storage tube
maintaining a screen image
store the picture information inside the CRT instead of refreshing the screen (Refresh CRT)
Flat-Panel Displays
emissive displays
convert electrical energy into light
nonemissive displays
convert other source into light
LCD(Liquid-Crystal Displays)

17. Graphics Software (1/2) Two general classifications
general programming package
provides an extensive set of graphics functions used by high level prog. lang (Fortran, C)
GKS (Graphical Kernel System)
2-D oriented package
PHIGS (Programmer’s Hierarchical Interactive Graphics Standard)
extension of GKS
Increased Capabilities for modeling, rendering
PEX (PHIGS Extension to X)
good for network environments

18. Graphics Software (2/2) Special purpose package Script Language
CGI (Computer Graphics Interface)
device interface methods
CGM (Computer Graphics Metafice)
standards for archiving and transporting pictures
Open GL & DirectX
Graphics Library
Special purpose package
design for nonprogrammer
ex) 3D MAXstudio, Topas, Autocad for PC
MAYA, WAVEFRONT, ALIAS, SOFTIMAGE for Workstations
Script Language
Render Man, Radiance, PovRay