Bob Lambermont - Petrobras Innovators in image processing.

Bob Lambermont - PetrobrasBob Lambermont - Petrobras

Innovators in image processingInnovators in image processing


Projection Technologies

• CRTCRT

• Light ValveLight Valve– DMDDMD– LCDLCD– D-ILA (LCOS)D-ILA (LCOS)


Projections : The basics

CRT

Lens

Light source = CRTImage source = CRT250 - 500 lumens3200 x 2500

Screen

Lamp

Light source = LampImage source = LCD2000 - 12000 lumens1280 x 1024

Screen

optical path

LCD and DMD

high resolution geometry mature technology flexible positioning photo-realistic

brighter maintenance alignment easy setup pixelization


CRTCRT technology technology


CRT technology

CRTs

Electronics Screen

Lenses


CRTCRT technology technology

7 inch 8 inch 9 inch 12 inch

Different tube sizeDifferent tube size


Scheimpflug correction

Projection can’t be done on tilted surfaceProjection can’t be done on tilted surface -> focus problem!-> focus problem!


Scheimpflug correction

Required for projection on tilted screensRequired for projection on tilted screens


A picture can be built up with the following three scanning methods:

Raster scan (standard CRT projector) Vector scan (e.g. radar screen) Raster-calligraphic (combination of two)

Geometry can easily be modified in raster scan through influencing of deflection fields

Picture build-up


Raster <->Calligraphic

Raster image 1280*1024 60Hz Day mode 1280*1024 60Hz

16 ms

Pixel remains onscreen for 10 ns Point remains onscreen for 1.5 µs

150 times longer !


Calligraphy

Raster Image

Calligraphic Light points


CRT technology

Strengths:Resolution (up to 2500x2000)Good contrast Easy geometrical correction / flexibility Color matching and uniformity Digital soft-edgeUnbeatable video and data image qualityLife time picture tubesProven technology

Weaknesses:

Limited brightness up to 500 ANSI LumenNeeds low ambient lighting conditionsSetup timeMaintenanceNot portable


Light valve projection

• PolarizationPolarization• LCDLCD• LCOSLCOS• DMDDMD

– 3-chip3-chip– single-chipsingle-chip


Polarization

Typical polarizer “eats” 50%Typical polarizer “eats” 50%of the unpolarized light powerof the unpolarized light power


LCD pixel

By applying voltageBy applying voltageover LCD pixel, over LCD pixel, transmission of lighttransmission of lightcan be modulated.can be modulated.


LCD panel: implementation

•Response speed limited Response speed limited by thickness and characteristicsby thickness and characteristicsof LC materialof LC material•transmission limited bytransmission limited byinterconnects and transistorsinterconnects and transistors•Increase in resolutionIncrease in resolutionnecessitates higher miniaturizationnecessitates higher miniaturization(can be compensated by microlenses)(can be compensated by microlenses)


Panel technologies

Amorphous SiAmorphous Si HT Poly SiHT Poly Si

• normal glass, low costnormal glass, low cost• larger transistorslarger transistors=> suitable for displays > 3”=> suitable for displays > 3”• external driversexternal drivers

• Quartz glass, expensiveQuartz glass, expensive• smaller transistorssmaller transistors=> suitable for displays < 2”=> suitable for displays < 2”• integrated driversintegrated drivers


LCD Panels

Panel sizes1.1-1.8 inch (p-Si)3 inch (a-Si)6 inch (a-Si)10 inch (single panel)


LCD pros and cons

+Well-established technology, stableWell-established technology, stable+Compact, rugged, portableCompact, rugged, portable+““zero delay”zero delay”+UXGA resolution availableUXGA resolution available+Efficient in passive stereo projection (see further)Efficient in passive stereo projection (see further)

-Response speed limited by LC materialResponse speed limited by LC materialsome smearing in fast moving imagessome smearing in fast moving images

-non-perfect black (contrast ratio 200-300:1, but improving)non-perfect black (contrast ratio 200-300:1, but improving)-pixellizationpixellization


LCOS: Liquid Crystal on Silicon

• Essentially: Essentially: LCD in front of a reflectorLCD in front of a reflector

• Available for Available for microdisplays, projectionmicrodisplays, projection

• D-ILA is JVC’s trade name D-ILA is JVC’s trade name for LCOSfor LCOS


LCOS implementation

• LCD on top of CMOS chip that includes LCD on top of CMOS chip that includes transistors and has reflective surfacetransistors and has reflective surface

• Aperture ratio is higher than that of LCD (so Aperture ratio is higher than that of LCD (so less pixel visibility)less pixel visibility)

• Efficiency comparable to LCD due to non-Efficiency comparable to LCD due to non-perfect reflectionperfect reflection

• Easy to cool the chip!Easy to cool the chip!


LCOS addressing

• Requires complex optics:Requires complex optics:side at which chip is illuminated is the same side at which chip is illuminated is the same as where the light needs to be extracted from!as where the light needs to be extracted from!


LCOS integration

Complex structure required!Complex structure required!


LCOS pros and cons

+ Higher resolutions possible (up to QXGA)Higher resolutions possible (up to QXGA)+ small chip size (1.3” and smaller)small chip size (1.3” and smaller)+ good response speedgood response speed+ good pixellization (smooth image)good pixellization (smooth image)+ higher contrast possible: up to and over higher contrast possible: up to and over

1000:1 reported1000:1 reported+ chips can be cooled to take high power chips can be cooled to take high power

illuminationillumination

- alignment hard due to small chip size & alignment hard due to small chip size & high reshigh res

- difficult to integratedifficult to integrate- uniformity? (although seems to be uniformity? (although seems to be

countered now)countered now)


DMD: another reflective tech

Ant leg on DMD chipAnt leg on DMD chip

Does not require polarized light!Does not require polarized light!


DMD microstructure

Only allows on/off modulation!Only allows on/off modulation!


DMD: grayscale synthesis

Frame delay!Frame delay!•1 frame for de-interlacing1 frame for de-interlacing•1 for sending data through CMOS chip1 for sending data through CMOS chip•0-1 frame (depending on gray scale) for gray synthesis0-1 frame (depending on gray scale) for gray synthesis


3-chip DMD integration

Each chip runs at 10 bits depth, 60 HzEach chip runs at 10 bits depth, 60 HzNOTE: 10 bit Linear Gamma equalsNOTE: 10 bit Linear Gamma equals 8 bit LCD Gamma8 bit LCD Gamma


3-chip DMD pros & cons

+Excellent picture quality (pixels almost invisible)Excellent picture quality (pixels almost invisible)+can take high power illuminationcan take high power illumination+long life (?)long life (?)+no smearing (but no smearing (but +good intensity uniformity, good color matchinggood intensity uniformity, good color matching+good contrast (400:1)good contrast (400:1)

-Expen$ive!Expen$ive!-BIG!BIG!-PWM artifactsPWM artifacts-TI monopoly TI monopoly -Frame delayFrame delay-Resolution limited to SXGAResolution limited to SXGA-Bright edge around chip makes optical blending difficultBright edge around chip makes optical blending difficult


Single-chip DMD

•Sequential illumination of single DMD chipSequential illumination of single DMD chip•3 or 4 segment color wheel3 or 4 segment color wheel•chip runs at 8 bit, 240 Hz chip runs at 8 bit, 240 Hz less bit depth!less bit depth!

+CompactCompact-Moving part inside, requires synchronizationMoving part inside, requires synchronization-Motion artifacts (color breakup) due to color wheelMotion artifacts (color breakup) due to color wheel

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Innovators in image processingInnovators in image processing

Bob Lambermont - Petrobras Innovators in image processing.

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