1 Graphics hardware Output devices Input devices

2 Overview CPU Hardcopy Display processor System memory Scanner Input devices LAN Image capture

3 Display devices Raster displays. CRT. Random (vector) displays LCD Plasma

4 Cathode Ray Tube - CRT Refresh rate Resolution Bandwidth

5 Color CRT

6 Phosphors spectrum

7 Random (vector) display Draws only lines Currently obsolete in computers Advantages: ― Fast refresh for simple scenes ― Easy line drawing ― No memory requirements Similar displays are in oscilloscopes

8 LCD technology - basics Randomly polarized light Crystal molecule Vertical polarizer Aligning glass Horizontal polarizer (Color) mirror

9 LCD technology - basics

10 LCD, reflective vs. backlit Reflective LCD require external light (watches) Backlit LCD are lit with fluorescent lamps (laptops)

11 Passive LCD Composed of horizontal and vertical wires A dark spot at (x 1,y 1 ) requires –V at x 1 and +V at y 1. What happens when we want black dots at (x 1,y 1 ) and (x 2,y 2 )? Points are selected in succession (one pixel at a time) Vertical polarizer Vertical wires Liquid Horizontal wires Horizontal polarizer Mirror

12 Active LCD Transistor attached to every grid point: Attached capacitors are able to hold the charge Fast response time Better grey level accuracy To display color filters are added

13 LCD

14 LCD vs. CRT comparison table CRTLCD PowerFairExcellent Screen sizeExcellentFair DepthPoorExcellent WeightPoorExcellent BrightnessExcellentGood ContrastExcellentFair ColorExcellentGood-Excellent Viewing angleExcellentPoor Response timeExcellentGood

15 Plasma Two panels of glass that hold tiny cells of neon and xenon Pros ― Fast response ― No need to refresh ― Great color gamut ― Bright ― Wide viewing angle Cons ― Price ― Power consumption ― Contrast

16 Hardcopy devices - terms Dot size Inter-dot spacing Resolution – number of distinguishable lines per inch Colors at a point

17 Hardcopy devices Plotter ― Moves pen across the surface ― Vector graphics ― Later plotters are raster ― Used for technical and CAD style plots ― High resolution over very large paper sizes

18 Hardcopy devices Dot matrix printer ― Print head with 7 to 24 pins (piece of wire) ― Each pin can be fired to strike a ribbon against the paper

19 Hardcopy devices Ink jet printer ― Spray microscopic dots of ink through small holes to form dots on paper. 4 colors (CMYK) in standard and up to 8 in photo printer are used. Thermal wax ― Creates colors by attaching wax paper to material and melting it. Used for special materials (shirts, plastic,…). Dye sublimation ― Creates continuous tones by heating dye until they turn into gas (sublimate) and fuses into the paper. ― Larger color gamut ― High cost per image

20 Hardcopy devices – Laser printer

21 Hardcopy devices – Laser printer The drum is positively charged by corona wire Laser discharges points Printer coats the drum with positively charged toner powder Paper is given strong negative charge to pull the toner from the drum and then discharged Finally the paper passes through the fuser (a pair of heated rollers) that melts the powder Color – 4 times through the process

22 Standard input devices Keyboard ― Alphanumeric Mouse ― Relative movement

23 2-D input devices Joystick ― Controlled by potentiometer ― Provides relative movement Digitizer / Tablet ― Controlled by electromagnetic or sonar sensing ― Provides absolute location Touch screen ― Different technologies that detect pressure / contact with the screen surface Light pen ― Synchronized with CRT, it can locate position on the screen

24 3D input device Wired glove Head mounted display Space ball Haptic devices ― Force / vibration feedback

25 Image capture Digital cameras ― Capture by CCD ― High resolution, up to 10Mp Video cameras ― CCD ― Lower resolution Scanner ― Digitizes a hardcopy image with CCD ― High resolution

26 Image capture Ultrasound ― High frequency waves ― Measures distance and intensity of the return way ― Standard ultrasound is 2D ― 3D image is built from several 2D images

27 Thermal imaging Non visible by human eye IR range mapped to visible range

28 3D scanners CT / MRI ― 3D imaging ― Radiation on tissue 3D range scanner ― Non contact ― Geometry and color texture digitizer ― Uses laser-light triangulation