Graphics System 2017, 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)

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

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%)

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

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

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

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)

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

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)

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

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

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

True Color System

Raster Graphics System Architecture

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) OLED(organic LED) Plasma Display Panels Field Emission Display CRT, LCD, PDP, LED 원리 비교

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 Today, most LCD screens are being designed with an LED backlight instead of the traditional CCFL(cold-cathode fluorescent lamps) backlight.

LED vs. PDP vs. LCD 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 Resolution: Winner: LED LCD, Loser: Plasma, Runner-up: LCD Motion blur: Winner: Plasma, Loser: LED LCD and LCD 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

LED LCD vs. OLED vs. plasma Light output (brightness): Winners: LCD, OLED (sort of), Loser: Plasma Black level : Winner: OLED, Loser: LCD, Runner-up: Plasma Contrast ratio: Winner: OLED, Loser: LCD, Runner-up: Plasma Resolution: Winner: LCD, Loser: Plasma, Runner-up: OLED Motion blur: Winner: Plasma, Loser/Runner-up: LCD and OLED Refresh rate: Winner: Plasma, OLED, LCD Viewing angle: Winner: Plasma, Loser: LCD, Runner-up: OLED Energy consumption: Winner: LED LCD, Runner-up: Plasma and OLED Price: Winner: Plasma (LCD depending on size), Loser: OLED, Runner-up: LCD Lifespan: Tie? Burn-in: Tie, sort of Uniformity: Winner: Plasma, Loser: LCD, Runner-up: OLED *Contrast ratio : the ratio between the darkest part of the image and the brightest *Burn-in : 고정된 화면을 장시간 켜놓거나 동일한 이미지가 반복될 경우 해당 이미지가 사라지지 않고 화면상에 남아 있는 현상 *Uniformity : a consistent brightness to the image http://news.danawa.com/News_List_View.php?nSiteC=3&nSeq=2441450&sMode=shopping&nBoardSeq=63

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

3D Display 3D Display 360° Light Field Display i3D — Head Tracking for iPad: Glasses-Free 3D Display Hologram Display

Input Device Input Device Keyboard, Mouse Button Boxes, Dials

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

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

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

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

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

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

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