2-displays_and_rasters

2-displays_and_rasters - Displays and Rasters Lecture 2...

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1 Displays and Rasters Lecture 2 CPSC 478/578 Spring 2005 ± Syllabus and lectures at http://classes.yale.edu/cpsc478b This week only: we meet FRIDAY Reading: Chaps. 3, 17, 18 ± Consider CPSC 479b/579b Sketch -B ased Interfaces and Modeling Syllabus ± Image processing ± Rendering ± Modeling ± Animation Overview Display hardware How images are displayed Raster graphics systems How imaging systems are organized Gamma Non-linearity of light perception Alpha Additional information at a pixel Color Representing and using it Display Hardware ± Video display devices Cathode Ray Tube (CRT) Liquid Crystal Display (LCD) Plasma panels Organic Light- Emitting Diodes (OLED) Projectors
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2 Calligraphic Displays ± Also called vector displays , stroke displays , or random-scan displays . ± Used by: Sutherland’s Sketchpad - Pen Plotters Asteroids video game Oscilloscopes Cathode Ray Tube (CRT) ± Evacuated glass bottle ± Heating element (filament) ± Electrons attracted to focusing anode cylinder ± Vertical and horizontal deflection plates ± Beam strikes phosphor coating on front of tube Color CRTs (or RGB monitors) ± T riads of red, green, and blue phosphors at each pixel ± Three electron guns, one per color ± Aligned shadow mask used to make each kind of phosphor “visible” from only one gun Delta electron gun arrangement In-line electron gun arrangeme Raster Displays ± Raster , from radere, “to scrape” ± Electron beam traces over screen in raster scan order ± Each left-to-right trace is called a scan line ± Each spot on the screen is a pixel ± When the beam is turned off to sweep back, that is a retrace , or a blanking interval Frame Buffer Refresh Refresh rate is usually 30-75Hz Interlaced Refresh Procedure ± Even/odd lines on alternate scans ± Entire screen painted 30 times/sec ± Screen is traversed 60 times/sec ± Interlace – a hack to give… smooth motion to dynamic scenes high resolution to static scenes
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3 Liquid Crystal Display (LCD) ± Laptops typically use liquid crystal displays (LCDs). Light enters a vertical polarizer from flourescnt tube Nematic crystal twists light based on applied voltage (more voltage, less twisting) Light passes through horizontal polarizer Liquid Crystal Display (LCD) ±
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2-displays_and_rasters - Displays and Rasters Lecture 2...

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