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Graphic Hardware

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Architecture of Graphics System

System Bus

CPUDisplay

ProcessorSystem Memory

Display Processor Memory

Frame Buffer

Video Controller

MonitorMonitor

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Basic Graphics System

Input devices

Output device

Image formed in FB

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IBM Advances inDisplay Technology

• In 1981, IBM introduced the Color Graphics Adapter (CGA) display, able to display 4 colors and max resolution of 320x200.

• In 1984, Enhanced Graphics Adapter (EGA) display, able to display 16 colors and resolution of 640x350.

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IBM Advances in Display Technology (cont.)

• In 1987, Video Graphics Array (VGA) display.– Most computers today support the VGA

standard.

• In 1990, Extended Graphics Array (XGA) display, capable of resolutions 800x600 in true color ( 16.8 million colors) and 1024x768 in 65,536 colors.

6of32 Pre-IBM

Apple II• Released in 1977 • First true “personal

computer” • Based on the Apple I

design with some additions– Plastic case– Able to display color

graphics

• Able to display 6 colors at 280x192 resolution.

7of32 Apple II Control Panel

8of32Windows Screen Shots Throughout

Time:

MS-DOS

Windows 3.1

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Windows 98

Windows 2K

Windows Screen Shots Throughout Time:

10of32 Displays

year 1984 1994 2004

size 640x480 1024x1280 1600x1200

Mpixels .3 1.3 1.9

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Pixels

Faceplate picture elements (pixels) are formed by depositing and patterning a black matrix, standard red, green, and blue TV phosphors and a thin aluminum layer to reflect colored light forward to the viewer.

12of32 Frame Buffers

• A frame buffer may be thought of as computer memory organized as a two-dimensional array with each (x,y) addressable location corresponding to one pixel.

• Bit Planes or Bit Depth is the number of bits corresponding to each pixel.

• A typical frame buffer resolution might be

• 640 x 480 x 8• 1280 x 1024 x 8• 1280 x 1024 x 24

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1-Bit Memory, Monochrome Display (Bitmap Display)

Electron Gun

1 bit 2 levels

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Examples of Pixel Depth Monochrome

• Monochrome graphics have one-bit pixel depth. (pure black or pure white)

15of32 3-Bit Color Display

3

red

green

blue

COLOR: black red green blue yellow cyan magenta white

R G B

0 0 0

1 0 0

0 1 0

0 0 1

1 1 0

0 1 1

1 0 1

1 1 1

16of32 True Color Display

Green

Red

Blue

8

8

8

24 bitplanes, 8 bits per color gun.224 = 16,777,216

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Examples of Pixel Depth8 Bit Colour

• 8 bits per pixel provides 256 colour choices (Typical of the web - that’s why web graphics need some skilful preparation)

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Examples of Pixel Depth

• 24 or 32 bits per pixel provides thousands or millions of colour choices. (Typical of graphics and games software)

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DAC

Direct Color Framebuffer• Store the actual intensities of R, G, and B individually in

the framebuffer• 24 bits per pixel = 8 bits red, 8 bits green, 8 bits blue

– 16 bits per pixel = ? bits red, ? bits green, ? bits blue

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Resolution

• Resolution refers to the density of dots on the screen or printed image and directly affects quality

• The higher the resolution, the less jagged the image.

• Resolution is measured in DPI (Dots per Inch)• (The printing industry is largely unmetricated and still uses inches

because printing measures such as the Point (1 72nd of an inch) do not easily convert to metric units.)

• The higher the resolution, the better the potential output.

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Typical Resolutions

• Screens generally operate at around 72-100 dpi• Printed images range from 300 to 2400 dpi• Resolution affects the file size of an image.• The higher the resolution, the bigger the file. • The visible resolution is limited to the maximum

possible on the output device (screen or printer).• No matter how high the resolution of a

photograph, it will show at the resolution of your screen or printer.

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Other meanings of resolution

• Dot Pitch [Display] - Size of a display pixel, distance from center to center of individual pixels on display

• Cycles per degree [Display] - Addressable elements (pixels) divided by twice the FOV measured in degrees.

• Cycles per degree [Eye] - The human eye can resolve 30 cycles per degree (20/20 Snellen acuity).

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TECHNOLOGIES

CATHODE RAY TUBE (CRT)

VACUUM FLOURECENT DISPLAY (VFD)

FIELD EMISSION DISPLAY (FED)

LIQUID CRYSTAL DISPLAY (LCD)

PLASMA DISPLAY PANEL (PDP)

ELECTROLUMINISCENT DISPLAY (EL)

ORGANIC LIGHT EMITTING DIODE (OLED)

24of32 VFD

Earliest Flat technology

Low Cost

Excellent Viewing Angle

Long Life

Matrix Addressing

Wire Emitters

Cathodoluminescent

Mechanical Complexity

Low Resolution

25of32 Display Technologies

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Basic Cathode Ray Tube (CRT)

Fire an electron beam at a phosphor coated screen

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27of321. Electron Guns

2. Electron Beams

3. Focusing Coils

4. Deflection Coils

5. Anode Connection

6. Shadow Mask

7. Phosphor layer

8. Close-up of the phosphor coated inner side of the screen

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Raster Scan Systems

Draw one line at a time

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29of32 Raster Scan Displays

• Picture definition is stored in a memory area called the refresh buffer or frame buffer.

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Raster Displays

• frame must be “refreshed” to draw new images

• as new pixels are struck by electron beam, others are decaying

• electron beam must hit all pixels frequently to eliminate flicker

• critical fusion frequency– typically 60 times/sec– varies with intensity, individuals, phosphor

persistence, lighting...

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Monitor Classifications

• Monochrome: Display two colors, one for the background and one for the foreground.

• Gray-Scale: A special type of monochrome monitor capable of displaying different shades of gray.

• Color: Can display anywhere from 16 to over 1 million different colors. Sometimes called RGB monitors.

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Colour CRT

An electron gun for each colour – red, green and blue

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33of32 Color CRTs

• three electron guns

• metal shadow mask to differentiate beams

34of32 Color CRTs

• three electron guns

• metal shadow mask to differentiate beams

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Color CRTs

• color CRTs much more complicated– requires manufacturing very precise geometry– uses a pattern of color phosphors on the

screen:

Delta electron gun arrangement In-line electron gun arrangement

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Display Technologies

• Cathode Ray Tubes (CRTs)– most common display device today– evacuated glass bottle– extremely high voltage– heating element (filament)– electrons pulled towards

anode focusing cylinder– vertical and horizontal deflection plates– beam strikes phosphor coating on front of tube

37of32 Monitor Quality and Resolution

Quality:• Manufacturers describe quality by dot pitch. • Smaller dot pitches mean pixels are closely

spaced which will yield a sharper image. • Most monitors have dot pitches that range from

0.22mm to 0.39mm. Resolution:• Indicates how densely packed the pixels are.• Most modern monitors can display 1024x768

pixels.• High end models can display 1280x1024.

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Flat-Panel Displays (Plasma)

Flat-Panel

Emissive Non-Emissive

LED

CRT(90°deflected)

Plasma

Thin-Filmelectroluminescent

LCD DMD

Active-Matrix

Passive-Matrix

ToshibaTM, 42”, Plasma HTDV

39of32 LCD

Most mature flat panel technology

Major share of FPD market

Poor intrinsic viewing angle

Requires backlight

Slow

Effected by Temperature and sunlight

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LCD History

• Liquid crystals were first discovered in 1888 by Austrian botanist Friedrich Reinitzer.

• When cooled, the liquid turned blue before finally crystallizing.

• RCA made the first experimental LCD in (1968).

• Manufacturers have been developing creative variations and improvements since on LCDs.

41of32 LCDs

• Liquid Crystal Displays (LCDs)– organic molecules, naturally in crystalline state,

that liquefy when excited by heat or E field– crystalline state twists polarized light 90º.

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LCDs

• transmissive & reflective LCDs:– LCDs act as light valves, not light emitters,

and thus rely on an external light source.– laptop screen: backlit, transmissive display– Palm Pilot/Game Boy

• reflective display

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Liquid Crystal Displays

Light passing through the liquid crystal is twisted so it gets through the polarizerA voltage is applied using the crisscrossing conductors to stop the twisting and turn pixels off

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Analog VS Digital signal handling

• On most graphic card signal goes through

DAC (digital to analog converter) to

convert to Analog signal.

• LCD must convert the signal back to digital

to determine which pixel to light.

45of32 Disadvantages of LCDs

• Response Time– It is much slower. The delay can cause a

ghosting effect on images it displays.

(Source: TechRepublic.com, PCWorld.com, TouchScreens.com)

46of32 Disadvantages of LCDs

• Resolution• Displays Native Resolutions (Resolution that it

displays best)

• Viewing Angle• Smaller, needed to be viewed more directly

from the front.• From the side the images on an LCD screen

can seem to disappear, or invert colors.• Newer displays that are coming out have a

wider viewing angle so this is not as much of an issue as it has been in the past.

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LED- Direct view- backlight source

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LCD: backlit

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LCD vs CRT

flat & Lightweight

low power consumption

always some light

pixel response-time (12-30ms)

view angle limitations

resolution interpolation required

heavy & bulky

strong EM field & high voltage

true black

better contrast

pixel response-time not noticeable

inherent multi-resolution support

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OLED

• Organic Light Emitting Diode (OLED)

• Kodak scientist Dr. Ching (1970’s)

• OLED materials reported in 1987

• Color improvements by 1989

• Becoming a major competetor with today’s LCD/plasma displays

51of32 Material technologiesMaterial technologies

Small molecules Small molecules

Molecules commonly used in OLEDs include organometallic  chelates

PeryleneAlq3 Tris(8-hydroxyquinolinato)aluminium

 chelate

Alq3 has been used as a green emitter, electron transport material and as a host for yellow and red emitting dyes.

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54of32

Device ArchitecturesDevice Architectures

• Bottom or top emission:• Transparent OLEDs: it much easier to view

displays in bright sunlight

• Inverted OLED:

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56of32

OLED/LED: What’s the diff?

• Both OLED and LED use the same principle of electroluminescence- the optical and electrical phenomenon where certain materials emit light in response to an electric current passing through it.

• OLED– Lighter weight– Perform at lower efficiencies– Less power consumption– Organic based chemicals

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OLED’s Today

• Various Mp3 players– Muzio JM-200 – Sony NW-E015F Walkman – Arcos 204

• Kodak’s LS633 3mpx digital camera

– Priced at 399$ – Good battery life – 2.2” OLED screen

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Continued…

• Mobile devices

– Apple iPhone

– Sony Ericsson W51S

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Companies

• Samsungs AMOLED display

– 12mm thick– 1600x1200 aspect ratio

• Sony intends to give OLED technology a shot, making OLED TV’s.

• Toshiba is holding off until 2015-2016

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…continued

• Disadvantages

– Short term battery life

– Expense

– Doesn’t like water

61of32 Plasma Display Panels

• similar in principle to fluorescent light tubes

• small gas-filled capsules excited by electric field,emit UV light

• UV excites phosphor

• phosphor relaxes, emits some other color

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Applying voltages to crossing pairs of conductors causes the gas (usually a mixture including neon) to break down into a glowing plasma of electrons and ions

Plasma-Panel DisplaysIm

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63of32 PDP Working

Address electrode causes gas to change to plasma state.

The plasma emits UV in discharge region which impinges on the phosphor

Reaction causes each subpixel to produce red, green, and blue light.

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Structure of a PDP

65of32 DMD / DLP Projectors• Digital Micromirror Devices

• Digital Light Processing– Microelectromechanical

(MEM) devices, fabricated with VLSI techniques

66of32 Additional Displays

• Display Walls– Princeton– Stanford– UVa – Greg Humphreys

67of32 Additional Displays

• Stereo

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Mobile Displays

640x480 1” colour640x480 1” colourvirtual image 2 ft awayvirtual image 2 ft away3 oz3 oz

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3D Printers

– spread layer of powder– print binder solution– vacuum away loose powder

4.5 hrs printing,4.5 hrs printing,$100 printing cost$100 printing costelectroplatedelectroplated

[Z Corp][Z Corp]

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3D Printers

printing telephones?printing telephones?etc.etc.

71of32 TECHNOLOGY ATTRIBUTES

Attribute PMLCD AMLCD LCOS PDP FED DLP OLEDSize < 15” <15” < 1” >30” <15” > 60” No limitBrightness nits < 100 <100 <100 <500 <500 <500 >10000Resolution Medium High High High High Medium HighInherent VA Small Small Medium Large Large Large LargeEfficiency lm/w 6 6 - 1 5 6 50Colour gamut Good Good Good Good Good Good GoodManuf. cost Medium V.High High Medium Medium High LowCost pid 1 5 5 1 2 3 <1Market presence Established Establish Established Entering ? Established

In 2 years

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Modern Graphics Hardware

73of32 Graphics Accelerator

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The Graphics Pipeline

75of32 Graphics Accelerator

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76

Modern Graphics Hardware

• Graphics Processing Units (GPUs)

• Programmable geometry and fragment stages

• 600 million vertices/second, 6 billion texels/second

• In the range of Tera operations/second

• Floating point operations only

• Very little cache

77of32 NVIDIA GPUs

  Quadro FX 5600 Quadro FX 4600Memory Size 1.5GB GDDR3 768MB GDDR3

Memory Interface 384-bit 384-bit Memory

Bandwidth 76.8 GB/sec. 67.2 GB/sec.

Max Power Consumption

171W 134W

Number of Slots 2 2Display

ConnectorsDVI-I DVI-I Stereo DVI-I DVI-I Stereo

Dual-Link DVI 2 2Price 2,999.00$ 1,999.00$

78of32 AMD GPUs

Desktop vs Mobility Radeon Graphics

 Desktop

Radeon HD 6990

Desktop Radeon HD

6870

Radeon HD 6990M

Transistors 5.28 billion 1.7 billion 1.7 billion

Engine Clock 830 MHz 900 MHz 715 MHz

Shader (ALUs)

3072 1120 1120

Texture Units

192 56 56

ROP Units 64 32 32Compute

Performance5.1 TFLOPS

2.01 TFLOPS

1.60 TFLOPS

DRAM TypeGDDR5-

5000GDDR5-

4200GDDR5-

3600

DRAM Interface

256-bits per GPU

256-bits 256-bits

Memory Bandwidth

160 GB/s per GPU

134 GB/s 115.2 GB/s

TDP 375 W 151 W 100 W

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79

Graphics Hardware

• High performance through – Parallelism – Specialization– No data dependency– Efficient pre-fetching

G

R

T

F

D

G

R

T

F

D

G

R

T

F

D

G

R

T

F

D

task parallelism

data parallelism

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80

Modern Graphics Hardware

• About 4-6 geometry units

• About 16 fragment units

• Deep pipeline (~800 stages)

• Tiling of screen (about 4x4)– Early z-rejection if entire tile is occluded

• Pixels rasterized by quads (2x2 pixels)– Allows for derivatives

• Very efficient texture pre-fetching– And smart memory layout

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V

rasterizer

F

rop

cross-bar

16 fragment units

16 raster operation unitsz buffer, framebufferScreen-locked

6 vertex units

16 texture unitsmipmap

filtering

ArchitectureV V V V V

F F F F F F F F F F F F F F F

TexTexTexTexTexTex

One big parallel rasterizer

rop

rop

rop

rop

rop

rop

rop

rop

rop

rop

rop

rop

rop

rop

rop

82of32

Bottlenecks?

GPUCPUapplication

potential bottlenecks

driver

• The bottleneck determines overall throughput• In general, the bottleneck varies over the

course of an application and even over a frame• For pipeline architectures, getting good

performance is all about finding and eliminating bottlenecks

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File Types

• There are many kinds of graphics file formats and this is a specialised area and a bit complicated.

• Examples : bmp GIF JPEG TIFF PICT Raw• For most applications involving photographic

images, use the JPEG file format (Joint Photographic Experts Group)

• For graphics or paint type files use GIFs(Graphical Interchange Format)

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JPEG

• The JPEG format can be used by most applications and all browsers

• It has very good compression algorithms• It stores a good quality image in a remarkably

small file with little or no loss of quality• JPEG offers 10 quality levels with

correspondingly smaller files and greater losses in quality

85of32 GIF

• You should choose a GIF format instead of JPEG when

– You have a graphic with only a few colours such as a logo or icon

– You want to create an image with some transparent parts for a web page

– You want the smallest possible file size with totally lossless compression

– You want to combine a few images together into an animation

– You want to save text as a graphic

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File Sizes

• A little knowledge is a dangerous thing!• With a little knowledge, you can create files that

are so large they are almost unusable• With a bit more knowledge you can store the

same image in a file that is a fraction of the size• With little or no loss of quality• You MUST understand this if you are going to

use graphics effectively

87of32 Example (without compression)

• A standard postcard is 6in by 4in in 8 bit colour (256 colours), the following is true

• At a resolution of 100 dpi the image is 600 by 400 dots so comprises 240,000 pixels. Each pixel is 1 byte so that’s

– 240000 bytes (240KB)

• At a resolution of 300 dpi it becomes 1800 by 1200 dots – 2160KB (2MB) That means it is now 9 times as big!

• At a resolution of 600 dpi it becomes 3600 by 2400 dots– 8640KB (8MB) - Now 36 times as big!

• And on screen you can’t see any difference!• Note - for 32 bit colour (millions of colours) the file sizes

are 4 times bigger again!

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Compression

• The previous example is for uncompressed files and ignores the fact that some file formats compress the data using very clever algorithms.

• With a good compression system, file sizes can be significantly reduced with little or no loss of quality.

• JPEG has compression built in at 10 quality levels but is a “lossy” algorithm. (Some data is gone forever when you compress)

• GIF compresses files with a “lossless” algorithm and so no quality is lost.

• When a file has a large number of colours, a GIF will generally create a much larger file than a JPEG

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Example of JPEG compression

JPEG Quality 10 File Size 100K JPEG Quality 1 File Size 32KBNot much loss even at the greatest compression

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A Simple Rule of Thumb

• For use in any screen based application such as PowerPoint or the internet, a 72 to 100dpi medium quality JPEG 4 will usually suffice

• UNLESS – you plan to crop a part of the image, enlarge it and

then use it at the larger size.

• Then – you would increase the original scanning resolution

accordingly

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Printing

• Even for images that will eventually be printed, there is little point scanning beyond 150 dpi unless you are producing a very high quality glossy colour magazine(in which case you would use 300dpi.)

• If you want to enlarge an image then you would scan at correspondingly higher resolution.

• If necessary, a low resolution image can be reduced in print size to effectively give a higher resolution image on paper

– e.g. if you halve the size of a 150 dpi image you have a 300 dpi image.

– Laser printers rated as 600 dpi only use 100 dpi in a graphic.

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Scanning Steps

• Make sure the scanner glass is clean

• Put your photo or graphic on the scanner bed.• Open Photoshop (or some other bit mapped graphics programme)

• Choose File / Import/ Twain / Acquire (or something similar)

• Ask for a prescan (or if it is automatic, wait for the prescan to finish)

• Crop the area that you want to scan properly

• Check the settings - use 100dpi for most purposes

• Press SCAN

• Save the image as JPEG then choose medium quality

• Experiment with the same scan at different resolutions and file types if you want to understand this better

Course Website: http://www.comp.dit.ie/bmacnamee

Then your photos can look as good as this