1. Graphics System
2012, Fall

2. Overview of Graphics System
Graphics Hardware
Video Display Devices
CRT Basic
Type of CRT
Random-Scan Displays
Raster-Scan-Displays
Flat-Panel Displays
Others
Graphics Software

3. Video Display Devices
Cathode-Ray Tube(CRT)
(cathode ray)

4. CRT Basic (1/2) Phosphor(형광체) refresh CRT Persistence
Emit a small spot of light contacted by the electron beam
refresh CRT
To maintain image, refresh electron beam repeatedly
refresh rate : frequency at which a picture is redrawn
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
general purpose graphic monitors : from 10 to 60 ms

5. 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) 4/3 : length of 4 points on horizontal line = length of 3points on vertical line
Spot Intensity (Gaussian distribution)
Overlap position (distinguishable  60%)

6. Type of Display Device Type of CRT Flat-Panel Displays
Random-Scan Displays
Raster-Scan-Displays
Flat-Panel Displays
Emissive displays
Nonemissive displays

7. 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, display program)
draw a picture one line at a time

8. Raster-Scan Displays (1/3)
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

9. Raster-Scan Displays (2/3)
Frame buffer
Depth of the buffer area, Number of bit planes
Bitmap: one bit per pixel
Pixmap: multiple bits per pixel
Refresh rate
Above about 24 frame per second
Unit of refresh rates  Hz
Ex) 60 frames per second (60Hz)

10. Raster-Scan Displays (3/3)
Retrace
Horizontal retrace/Vertical retrace
Interlaced refresh procedure
used with slower refreshing rates
avoid flicker
provide adjacent scan lines

11. 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)

12. 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 Bitmap

13. Raster Displays (Pixmap)
With multiple bits per pixel, we can display gray-scale or color pictures
the frame buffer is commonly called pixmap
Ex) Size of Frame Buffer when N=3, with 512 X 512
Size of Frame buffer = 3 X 512 X 512 = 3 X 256k = 768k

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

15. True Color System

16. Raster Graphics System Architecture

17. Flat-Panel Displays (1/2)
Video devices that have reduced volume, weight, and power requirement compared to a CRT
emissive displays
convert electrical energy into light
Plasma Display Panels (PDP)
Less efficient than CRTs (Not as bright, More power)
Large Pixels(~1mm compared to 0.2mm for CRT)
Field Emission Devices (FED)
Limited in size
Light-Emitting Diode (LED)
LED-backlight LCD television
Plasma Display Panels
Field Emission Display

18. Flat-Panel Displays (2/2)
nonemissive displays
convert other source (heat, electromagnetic force,..) into light
Liquid-Crystal Displays (LCD)
Liquid Crystal
The LCD's transition between crystalline and liquid states
less energy on average than their plasma counterparts
a limited viewing angle relative to CRT and plasma displays

19. LED vs. PDP vs. LCD (1/2) LED LCD vs. plasma vs. LCD
Light output (brightness) Winner: LED LCD, Loser: Plasma, Runner-Up: CCFL LCD
Black level Winner: Plasma, Loser: CCFL LCD, Runner-up: LED LCD
Contrast ratio : the ratio between the darkest part of the image and the brightest Winner: Plasma, Loser: CCFL LCD, Runner-up: LED LCD
Viewing angle Winner: Plasma, Loser: CCFL LCD/LED LCD

20. LED vs. PDP vs. LCD (2/2)
Energy consumption Winner: LED LCD, Loser: Plasma, Runner-up: CCFL LCD
Price Winner: CCFL LCD, Loser: LED LCD, Runner-up: Plasma
Lifespan Tie
Burn-in : 고정된 화면을 장시간 켜놓거나 동일한 이미지가 반복될 경우 해당 이미지가 사라지지 않고 화면상에 남아 있는 현상 Tie
Uniformity : a consistent brightness to the image Winner: Plasma, Loser: CCFL LCD/LED LCD

21. Viewing Systems Wide screen view Large-screen stereoscopic view
Multi-panel display
Curved viewing screen

22. 3D Display 3D Display 360° Light Field Display Philips 3DTV
Hologram TV

23. Input Device
Input Device
Keyboard, Mouse
Button Boxes, Dials

24. Input Device Trackballs Spaceballs Joysticks Data grove
A ball device that can be rotated
with fingers
Spaceballs
Provide six degrees of freedom
Joysticks
Data grove

25. Input Device Digitizer
Device for drawing, painting, or interactively selecting position
Graphics tablet
3D digitizer
Desktop tablet
3D digitizing system
Artistic Digitizer System

26. Input Device Image Scanners flatbed scanner Hand-held scanner
Wide-format scanner

27. Input Device Plasma panels with touch screens
Resistive touch screen overlays
Light pen
Voice system

28. Hard-Copy Devices Picture generated on a dot-matrix printer
Roll-free pen plotter
Desktop pen plotter

29. Graphics Software (1/2) Two general classifications
general programming package
provides a library of graphics functions that can be used in a programming language such as C, C++, Java, or Fortran
CG API
Computer-graphics application programming interface
Ex) GL, OpenGL, VRML, Java2D, Java3D, Direct3D
Special purpose package
design for nonprogrammers who want to generate picture, graphs
ex) 3D MAXstudio, Autocad, MAYA, WAVEFRONT, ALIAS, SOFTIMAGE for Workstations

30. Graphics Software (2/2) Software standard Script Language
GKS (Graphical Kernel System) 1984
2-D oriented package
PHIGS (Programmer’s Hierarchical Interactive Graphics Standard)
extension of GKS
Increased Capabilities for modeling, rendering
OpenGL
GL (Graphics Library)  Hardware Independent
OpenGL Architecture Review Board
Script Language
Render Man, Radiance, PovRay