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  1. Revision

  2. Multimedia 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

  3. Perception • Electromagnetic spectrum

  4. Colour Sources/Displays • Types • Active sources - monitors • Passive sources - printed documents • Primary Colours (RGB,CMY) • Principle of Operation

  5. Colour Models • Colour Gamut • Human Colour Sensitivity • Other Colour Models • HLS • HSV

  6. True Colour Image Data Model

  7. Palette Colour Image Data Model R G B 165 16 49

  8. True colour Vs. Palette colour • True Colour: • High quality • Expensive hardware • Require more memory (normally 3 times) • Palette Colour • Limited number of colours • Cheap hardware • Enables easier implementation of certain techniques

  9. Image Formats • Two principle methods of representing graphical data • Vectors • Bitmaps (raster or pixel maps) • Lossless Compression • Lossy Compresion • Advantages/Disadvantages

  10. GIF Signature Identifies GIF and format GIF87A or GIF89A Screen Descriptor Global Colour Map Image Descriptor Local Colour Map Repeated 1 to n times Image Data GIF Terminator Graphics Interchange Format(GIF) • Advantages/Disadvantages • File Format • Function of each section • Animated • Transparent

  11. Joint Photographic Experts Group • JPEG • Advantages/Disadvantages • JPEG stages • Approximate compression • Problems of over-compression

  12. The Internet & Networked Multimedia • Interconnected set of networks • Design principles • Interoperability • Uniform naming and addressing • Layering • Simplicity • End-to-end protocols

  13. Uniform naming and addressing • The IP 32-bit addressing structure • 139.184.14.13 • Domain Name Servers (DNS) • Purpose • Function • DNS process • Domain Names • IP addresses • Classes

  14. Layering • Reason for using layered system • Function of each layer Application Layer (e.g. HTTP, SMTP) Transport Layer (TCP, UPD) Network Layer (IP) Physical Layer (e.g.Ethernet)

  15. Version Header Length Type of service Total Length Identification D M Fragment Offset Time-to-live Protocol Header checksum Header Source IP Address Destination IP Address Options Data (<=64kB) Internet Protocol • The main functions of IP • IP Datagrams and packets in general • Datagram structure • IP Security • Routers

  16. Source port Destination port Sequence Number Header Acknowledgement Number Reserved Data offset Flags Window Checksum Urgent Pointer Data Transmission Control Protocol (TCP) • What does it provide that IP doesn’t? • Purpose • Operation • TCP connection set-up

  17. Web Pages • Static • HTML • SHTML • Dynamic • NSF • ASP • PHP • CGI • Server side and Client side scripting

  18. I B B P B B P B B I Digital Video • Moving Picture Experts Group MPEG2 • Operation • Compression

  19. Video Displays • Display technology • Cathode Ray Tube • Flat panel displays • Liquid Crystal (LCD) • Operation • Advantages/Disadvantages

  20. Colour CRT Displays • General operation • Function of: • Electron guns • Phosphors • Raster scan • Shadow mask / Aperture grill

  21. CRT Displays • Dot pitch • Resolution • Scanning • Interlaced • Non-interlaced • Frame/ Refresh rate • Scan rate • Dot clock • Screen sizes • Screen Curvature

  22. Colour Liquid Crystal Displays • Light source • Reflected • Generated • backlit • edgelit • Operation of a Colour LCD • Nematic Technology • Passive • Active

  23. Graphics • 2D Graphics • Vector • Bitmap • 3D Graphics • Coordinate system X,Y,Z • Geometry data • Texture data • Defining 3D objects • Graphics Pipeline

  24. Defining 3D Objects • Objects in the 3D scene and the scene itself are transformed through five spaces when proceeding through the 3D pipeline • Model Space • World Space • View Space • Clip Space • Screen Space • Function of each

  25. View Frustrum and Clipping • View frustrum • Purpose • Operation • Clipping • Purpose • Operation • Perspective divide

  26. Graphics Pipeline • Purpose and Operation • Stages • Application/Scene • Geometry • Translation • Rotation • Scaling • Skewing • Triangle Set-up • Rasterization / Rendering

  27. Fin Fin