Display Blocks EE367/CS448I: Computational Imaging and Display stanford.edu/class/ee367 Lecture 14 Gordon Wetzstein Stanford University
Logistics • final project poster presentations: Wed 3/11, 3:00-5:30pm, Packard Atrium • use poster template from website – poster printing instructions to follow • your poster must be up by 2:30pm; at least one of your team should be at the poster until both the instructor and your project mentor talked to you • 3-4 minute presentations for each poster – get to the point quickly: what is the goal of your project? what is your approach to getting there? what results did you get? where were the challenges? how does it compare to other approaches? how did you evaluate your method?
Logistics • final project poster presentations: Wed 3/11, 3:00-5:30pm, Packard Atrium • there’s s another eve vent at 6pm in the sa same location, so so we must st clear the area! • inst structors s will st start at 3pm sh sharp! if we are at yo your post ster and yo you’re not ready y to prese sent, yo your team will get a sc score of 0 • if yo you prese sent for more than 4 minutes, s, we will decrease se the sc score of yo your prese sentation! You sh should rehearse se and time yo your post ster pitch!
Logistics – see website • final reports & commented source code due Friday 3/13, midnight • CO CODE DE : should run out of the box! should be commented. should contain all data necessary to run it. should contain a README file and be obvious what to run • REPORT: ~6 pages (2000 words avg, 4000 max), use latex template provided on website (or comparable), should look like a conference paper: abstract, introduction, related work, your method (with equations, pseudo-code, algorithmic details, flow chart, …), experimental results, analysis and evaluation, comparison to previous work, discussion, limitations, conclusion, references
Tupac & Snoop Dogg – Live at Coachella 2012
Gorillaz & Madonna @ Grammy Awards 2006
John Henry Pepper, 1862 Pepper’s Ghost
http://www.redbubble.com/people/melek0197/works/9472644-childs-reflection-in-train-window
Pepper’s Ghost hidden room visible room not directly visible! beam splitter (green) wikipedia viewing window (red)
Pepper’s Ghost - Lighting wikipedia Same as all near-eye augmented reality displays!
Google Glass
Google Glass electroembedded.blogspot.com/2014/03/google-glass.html
Google Glass
Digital Displays - Overview • spatial light modulators • liquid crystal displays • projection displays • gamut mapping displayblocks.org • stereo displays • light field displays • of course: digital pepper’s ghost & AR!
Spatial Light Modulators (SLMs) • some typ so ype of sp spatially-va varyi ying light modulation (amplitude or phase se) Liquid Crystal Display (LCD) Liquid Crystal Display Digital Micromirror Device (DMD) on Silicon (LCoS) • Light Emitting Diodes (LEDs) and OLEDs E Ink mirasol • pixtronix • Ost stendo • quantum dots …
Light Emitting Diodes (LED) wikipedia
Light Emitting Diodes (LED) wikipedia
LED Displays
White LEDs • either multiple dies s (i.e. R+G+B dies) s) • or blue die + phosp sphor wikipedia blue LED blue LED + phosphor (Ce:YAG)
Organic Light Emitting Diodes (OLEDs) • electroluminesc scent material is s organic • can can be be pr print nted, ed, e. e.g. g. on on flexi xible su subst strates Samsung Galaxy Note Edge LG
OLED – Active vs Passive Matrix howstuffworks.com
Active vs Passive Matrix Addressing Scheme active ve matrix passi ssive ve matrix • • more complex electronics (1 simpler electronics • capacitor & 1 transistor per pixel) “dead” time between pixel • pixel can “store” information, e.g. updates – can lead to while scanning over the rest of the flicker (slow response) • screen imprecise voltage control • similar to phosphor lifetime in CRT
https://www.youtube.com/watch?v=mnh3lt8rnUk Active vs Passive Matrix Addressing Scheme
Liquid Crystal Displays • most common displays for monitors and TVs
LCDs - Twisted Nematic (TN)
LCDs - Twisted Nematic (TN) relaxed (twisted), crystalline state plc.cwru.edu/tutorial/enhanced/files/lcd/tn/tn.htm
LCDs - Twisted Nematic (TN) voltage applied: un-twisting – liquid state plc.cwru.edu/tutorial/enhanced/files/lcd/tn/tn.htm
LCDs – In-plane Switching (IPS) • electrodes on same side • in-plane LC alignment • pro: more consistent wikipedia across viewing angles, don’t change color when touched • con: more power, slower, more expensive than TN
wikipedia
LCD Subpixels IPS wikipedia S-IPS IPS TN subpixels
LCD Subpixels - Pentile Pixels • exotic subpixel layouts with different advantages and disadvantages
extremetech.com LCD Backlight wikipedia
LCD Backlight – CCFL vs LED • used to be: cold-cathode fluorescent lamps • now mostly LEDs: last longer, brighter, thinner, lower power, but a bit more expensive
extremetech.com LCD Backlight … at the end, you have a “light box” backlight enhancing films Cornelissen, SPIE 2008
Directional Backlight - Leia Fattal et al. 2013
Quantum Dots (QD) • se semiconductor nanocryst ystal • ext xtremely y narrow, tunable emissi ssion sp spectrum (vi visi sible+IR) • band gap (which determines s emitted wave velength) is s inve verse sely y proportional to dot si size ze • quantum dot disp splays ys use sed in LCD backl klight (we’ll get back k to that a but later) by y QD Visi sion
Quantum Dots wikipedia
http://www.ravepubs.com/ quantum-dots-the-end-of-white-leds-in-backlights/ Quantum Dot Backlight – QD Vision
Liquid Crystal on Silicon (LCoS) • basi sically y a reflective ve LCD • st standard component in projectors s and head mounted disp splays ys • use sed e.g. in googl google glass ss nd polarize • without 2 nd wit zer: phase se modulation!
Electronic Ink (E Ink) • reflective ve disp splay y – no active ve lighting! • high contrast st, low power • bist stable • inve vented by y Jo Joe Ja Jacobse sen
Mirasol (Qualcomm) • in interferometric ic modulator disp splay y (IMOD (IMOD) • color from gap si size ze (changed vi via MEMS) • intensi sity y from su subpixe xels – low res?! s?!
Digital Micromirror Device (DMD) • deve veloped by y Texa xas s Inst struments • MEMS devi vice • binary y st states s (e.g. +/- 10 10 degrees) s) • gr gray ay-leve vel through pulse se width mo modulati tion (P (PWM) M) Texas Instruments
Digital Micromirror Device (DMD) • when use sed in projector, usu sually y called digital light processi ssing devi vice (DLP)
Digital Light Processing (DLP) Projectors • color multiplexe xed in time (field se sequential color) • for exa xample usi sing color wheel in DPL projectors
Anatomy of a Projector (without the light) Projection Lens Diffuse Screen Modulator Viewer
LCD Projectors • 3 se separate optical paths s (1 per per col color or channel channel) opticsbalzers.com/en/237/LCD-projector.htm • sp splitting vi via dichroic mirrors • se separate modulation vi via transm smissi ssive ve LC LCDs • combination vi via x-cube cube prism sm • pr proj oject ection on lens ens
LCD Projectors light so source (d (dichro roic) ) mirro mi rrors rs http://wordpress.mrreid.org/ LC LCDs x-cube prism sm pr proj oject ection on lens ens
Scanned Laser Pico Projectors • biaxi xial MEMS sc scanner • 43.2 ° by y 24.3 ° at 43. at 60 60 Hz 1 mm Microvision, Freeman et al. 2009
Scanned Laser Pico Projectors Microvision, Freeman et al. 2009
Holographic Laser Projectors • deve veloped by y light blue optics • coher coherent ent light ght – phase se modulation in Fourier plane
Laser/LCD Projector announced by Sony • phosp sphor+blue lase ser = white (sa same as s white LED)
Scanning Fiber Projector • Schow Schowenger engerdt dt et al., Unive versi sity y of Wash shington • now now at at Magi agic c Leap Leap
Questions?
Stereoscopic and 3D / Light Field Displays many slides from Douglas Lanman (thanks)
Some Depth Cues of the HVS binocular disp sparity conve vergence mo motion para rallax accom accommod odat ation/ on/blur ur current glasse sses-base sed (st stereosc scopic) disp splays ys near near-term: compressi ssive ve light field disp splays ys lo longer-term: holographic disp splays ys
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