1 revision. 2 multimedia systems 2 lecture 1 - introduction to multimedia lecture 2 - perception...
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RevisionRevision
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Multimedia Systems 2Multimedia Systems 2 Lecture 1 - Introduction to Multimedia Lecture 2 - Perception (Light and colour, true and palette colour) Lecture 7 - Image Formats (vector/bitmap, GIFF, JPEG etc.) Lecture 3/4 - The Internet & Networked Multimedia Lecture 5 - The World Wide Web Lecture 6 - Web Pages Lecture 8 - Digital Video (MPEG) Lecture 9 - Streaming Video Lecture 10 - Multimedia Design Lecture 11 - Video Displays Lecture 12 - Display Adapters Lecture 13 - Graphics Lecture 14 - 3D Graphics Accelerator Cards & APIs Lecture 15 - Communications Theory
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PerceptionPerception
Electromagnetic spectrum
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Colour Sources/DisplaysColour Sources/Displays
TypesActive sources - monitorsPassive sources - printed documents
Primary Colours (RGB,CMY)
Principle of Operation
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Colour Models Colour Models
Colour GamutHuman Colour SensitivityOther Colour Models
HLSHSV
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True Colour Image Data Model
True Colour Image Data Model
Y
X
Pixel
Image
R G B
Colour
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Palette Colour Image Data Model
Palette Colour Image Data Model
Y
X
Pixel
Image
Index
R G B
Palette
R G B
Colour
165 16 49
R G B
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True colour Vs. Palette colour
True colour Vs. Palette colour
True Colour:High qualityExpensive hardwareRequire more memory (normally 3 times)
Palette ColourLimited number of coloursCheap hardwareEnables easier implementation of certain
techniques
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Image FormatsImage Formats
Two principle methods of representing graphical dataVectorsBitmaps (raster or pixel maps)
• Lossless Compression
• Lossy Compresion
Advantages/Disadvantages
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Graphics Interchange Format (GIF)
Graphics Interchange Format (GIF)
Advantages/DisadvantagesFile FormatFunction of each sectionAnimatedTransparent
GIF Signature
Screen Descriptor
Image Descriptor
Global Colour Map
Local Colour Map
Image Data
GIF Terminator
Repeated 1 to n times
Identifies GIF and format
GIF87A or GIF89A
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Joint Photographic Experts Group
Joint Photographic Experts Group
JPEGAdvantages/DisadvantagesJPEG stagesApproximate compressionProblems of over-compression
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The Internet & Networked Multimedia
The Internet & Networked Multimedia
Interconnected set of networks Design principles
Interoperability Uniform naming and addressing Layering SimplicityEnd-to-end protocols
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Uniform naming and addressing
Uniform naming and addressing
The IP 32-bit addressing structure139.184.14.13
Domain Name Servers (DNS)PurposeFunctionDNS process
Domain Names IP addresses
Classes
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LayeringLayering
Reason for using layered systemFunction of each layer
Application Layer (e.g. HTTP, SMTP)
Transport Layer (TCP, UPD)
Physical Layer (e.g.Ethernet)
Network Layer (IP)
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Internet ProtocolInternet Protocol
The main functions of IP IP Datagrams and packets in general
Datagram structureIP SecurityRouters
M
Version Header Length Type of service
Total Length
Identification
Fragment OffsetD
Time-to-live Protocol
Source IP Address
Header checksum
Data (<=64kB)
Options
Destination IP Address
Header
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Transmission Control Protocol (TCP)
Transmission Control Protocol (TCP)
What does it provide that IP doesn’t?PurposeOperation
TCP connection set-up
Source port
Destination port
Sequence Number
Acknowledgement Number
Data
Urgent Pointer
Data offset
Reserved Flags
Window
Checksum
Header
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Web PagesWeb Pages
StaticHTMLSHTML
DynamicNSFASPPHPCGI
Server side and Client side scripting
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Digital VideoDigital Video
Moving Picture Experts Group MPEG2OperationCompression
I B B P B B P B B I
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Video DisplaysVideo Displays
Display technologyCathode Ray TubeFlat panel displays
• Liquid Crystal (LCD)
OperationAdvantages/Disadvantages
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General operation Function of:
Electron gunsPhosphors Raster scanShadow mask /
Aperture grill
Colour CRT DisplaysColour CRT Displays
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CRT DisplaysCRT Displays
Dot pitchResolutionScanning
InterlacedNon-interlacedFrame/ Refresh rateScan rateDot clock
Screen sizesScreen Curvature
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Colour Liquid Crystal Displays
Colour Liquid Crystal Displays
Light source ReflectedGenerated
• backlit• edgelit
Operation of a Colour LCDNematic TechnologyPassiveActive
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GraphicsGraphics
2D GraphicsVectorBitmap
3D GraphicsCoordinate system X,Y,Z Geometry dataTexture dataDefining 3D objectsGraphics Pipeline
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Defining 3D ObjectsDefining 3D Objects
Objects in the 3D scene and the scene itself are transformed through five spaces when proceeding through the 3D pipelineModel SpaceWorld SpaceView SpaceClip SpaceScreen Space
Function of each
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View Frustrum and ClippingView Frustrum and Clipping
View frustrumPurposeOperation
ClippingPurposeOperation
Perspective divide
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Graphics PipelineGraphics Pipeline
Purpose and OperationStages
Application/SceneGeometry
• Translation
• Rotation
• Scaling
• Skewing
Triangle Set-upRasterization / Rendering
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FinFin
Fin