Graphics and Multimedia Foundation Computing The beatings will continue until morale improves.

2 of 41 What is Multimedia?  Literally, the combination of two or more types of media or effects: text graphics photographs sound video animation

3 of 41 Uses of Multimedia  Marketing  Education & Training  Computer Aided Design (CAD)  Desktop Publishing  Games  Movie Making  Virtual Reality

4 of 41 Uses of Graphics  Diagrams  Graphs and Charts, eg. Excel  Clip Art  Photographs  The graphical user interface of Windows, eg. icons, menus, etc.

5 of 41 Monitors, Printers & Pixels  In order to see graphics on a screen or printer it must be represented as lots of dots – PIXELS  A computer screen in made up of lots of pixels, perhaps 800  600 or 1024  768  A printer also assembles a printed page as lots of dots, perhaps 600 dpi for a good laser printer

6 of 41 How Much Memory?  Say we want to store a photograph to go as our screen background  Perhaps 800  600 pixels  Perhaps 24 bit colour, ie. about 16 million colours, requires 3 bytes per pixel  The complete uncompressed image file requires 800  600  3 bytes = 1.44 Mb (same as a complete floppy disk)

7 of 41 Bitmapped Graphics  If we store every pixel of a graphical image, we call this a bitmap  Stored in Windows BMP files and other compressed formats, eg. JPEG & GIF files  Can be black & white, greyscale or full colour (8, 16 or 24 bits per pixel)  Also known as raster graphics

8 of 41 How to Generate Bitmaps?  A scanner  A digital camera  A screen dump, eg. PrintScreen  A PAINT program, eg. Windows Paint  A photographic editing program, eg. Microsoft Photo Editor or Adobe PhotoShop

9 of 41 Shortcoming of Bitmaps  They take up a lot of memory!  Difficult to edit because there is no structure, just a whole lot of pixels  Difficult to enlarge without the jagged edges of the pixels becoming visible

10 of 41 Bitmaps 100% 200% 400% 800%  Bitmap - enlarged

11 of 41 Vector Graphics  The alternative to bitmaps is to store the structure of a diagram as objects, eg. lines, circles, arrows and other shapes  Each object within the diagram can have characteristics such as line width and colour, fill colour and shading etc  A complete diagram is a collection of graphical objects  A rendering program takes the vector graphic description and converts to a bitmap at a specific size

12 of 41 How to Generate Vector Graphics?  Must create manually using a DRAWING program  Examples: MS Office has a built-in set of drawing tools that are common to programs like Word and PowerPoint Engineering and Architectural CAD (computer aided design) programs

13 of 41 Advantages of Vector Graphics  Can take up less memory because don't have to store individual pixels  Individual objects within a complete vector graphic diagram can be edited, removed etc.  Vector graphic objects and diagrams can be resized without any distortion or jagged edges appearing

14 of 41 Vector Graphics 100% 200% 400% 800%  Vector graphic – enlarged

15 of 41 Disadvantages of Vector Graphics  No standard interchange format - every software program has its own format!  SVG (Simple Vector Graphics) from W3C is an emerging open standard  Windows uses Windows Metafiles (.WMF) but these are often embedded inside a Word or PowerPoint file  Cannot store scanned images or photographs as vector graphics.  Limited capability for artistic drawing

16 of 41 Graphics on the Internet  The widespread use of graphics on the World Wide Web has led to a number of common COMPRESSED graphics formats  The three most common, supported by all Web Browsers, are: GIF (Graphics Interchange Format) JPEG (Joint Photographic Encoding Group) PNG (Portable Network Graphics)  All are bitmap formats

17 of 41  Table Based Table of colours in image Each pixel has index to table Example: GIF (256 colour limit) Good for simple images like icons Image Compression

18 of 41 Image Compression (2)  Lossy Compression Similarity of neighbouring pixels stored How much info and how far  quality Example: JPEG Good for photographs

19 of 41 Image Compression (3)  Photo image (222x198 pixels) JPEG 7KB GIF 84KB BMP 128KB WMF 128KB

20 of 41 Image Compression (4)  Photo image (222x198 pixels) Reduced quality Higher compression JPEG 3KB

21 of 41 Image Compression (5)  Photo image (222x198 pixels) Very low quality Very high compression JPEG 1KB

22 of 41 Image Compression (6)  PNG version of JPEG image 84 kbytes!! vs 7 kbytes for JPEG

23 of 41 Image Compression (7)  Clipart image (in bitmapped formats 748x543) GIF 19KB JPEG 29KB WMF 83KB BMP 1,190KB

24 of 41 Image Compression (8)  A drawing (in bitmapped formats 548x499 pixels) WMF 3KB GIF 3KB JPEG 6KB BMP 268KB

25 of 41 JPEG versus GIF/PNG FormatGIFJPGPNG Colour TableYesNo Colours25616 million TransparencyYesNoYes AnimationYesNo LossyNoYesNo Good forSimple Diagrams Photos or artwork Complex Diagrams

26 of 41 Generating GIF/JPEG/PNG files  Use SAVE AS functionality of most graphics programs, eg. Microsoft Paint and Microsoft Office Picture Manager  With GIF select greyscale or 256 colour  With JPEG select greyscale or 24 bit colour, and also select quality. Lower quality  more compression  smaller file  See Study Book for example of file sizes

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30 of 41 Sound  Sound is a vibration of the air, or more precisely, a variation in air pressure  It is an analogue quantity (continuously varying)  To store on a computer it must be digitised  At regular intervals the pressure (usually in the form of a voltage from a microphone) is sampled

31 of 41 Sound Digitisation (Pulse Code Modulation, PCM)

32 of 41 Sound Formats  Uncompressed PCM formats: Microsoft Wave Format (.WAV files) Microsoft Resource Interchange File Format (.RIFF)  Compressed PCM formats: Window Media Audio (.WMA files) The audio side of MPEG-1 Video (.MP3 files) Ogg Vorbis - open and patent free

33 of 41 Sound Formats (2)  Other formats: Musical Instrument Digital Interface (.MIDI files) designed for music

34 of 41 Sound Formats (3)  MP3 players can often also play.WAV files  MP3 format much smaller than WAV, can be 1/10 of size CD can hold 700MB, or 74 minutes of uncompressed audio In MP3 format, CD of the same size can easily hold 740 minutes of audio!!!

35 of 41 Sound Formats (4)  Play audio on computer using Windows Media Player, or download software from the Web, eg MusicMatch Jukebox  May be able to convert between formats  Often cannot hear difference between MP3, WAV

36 of 41 Audacity

37 of 41 Sound Formats (4)  Play audio on computer using Windows Media Player, or download software from the Web, eg MusicMatch Jukebox  May be able to convert between formats  Often cannot hear difference between MP3, WAV

38 of 41 Animation, Video and Movies  Many formats supported by various programs: Moving Picture Experts Group (.MPG  MPEG-1 for Video CDs, output quality similar to VCR quality  MPEG-2 for commercial DVD movies  MPEG-1 is playable by MPEG-2 players

39 of 41 Animation, Video and Movies (2) Microsoft Audio Visual Interleave (.AVI files)  DV uncompressed  DivX compression  Xvid compression  Many more …

40 of 41 Animation, Video and Movies (3) Apple Quicktime Moving Pictures (.MOV) Windows Movie File (.WMV files) Macromedia Flash (.FLA or.SWF) usually used with a Web browser plugin animated GIF (no audio) Streaming vs download These four are commonly used for web delivery

41 of 41 Animation, Video and Movies (4)  Movie compression: each frame is an image, can compress, can also store changes from one frame to the next only