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Graphics System

Graphics System. 2012, Fall. 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. Video Display Devices. Cathode-Ray Tube(CRT). (cathode ray).

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Graphics System

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  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) • 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 • 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 Overlap position (distinguishable  60%) Spot Intensity (Gaussian distribution)

  6. Type of Display Device • Type of CRT • 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 • Beam-penetration • Two layers of phosphor(red, green) • Raster-scan monitor • Shadow Maskmethod • 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) • Flat-Panel Displays • 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 • http://www.rambus.com/kr/technology/applications/display/index.html 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 levelWinner: Plasma, Loser: CCFL LCD, Runner-up: LED LCD • Contrast ratio : the ratio between the darkest part of the image and the brightestWinner: Plasma, Loser: CCFL LCD, Runner-up: LED LCD • Viewing angleWinner: Plasma, Loser: CCFL LCD/LED LCD

  20. LED vs. PDP vs. LCD (2/2) • Energy consumptionWinner: LED LCD, Loser: Plasma, Runner-up: CCFL LCD • PriceWinner: CCFL LCD, Loser: LED LCD, Runner-up: Plasma • LifespanTie • Burn-in : 고정된 화면을 장시간 켜놓거나 동일한 이미지가 반복될 경우 해당 이미지가 사라지지 않고 화면상에 남아 있는 현상Tie • Uniformity : a consistent brightness to the imageWinner: 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 • 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 • 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

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