Multimedia

Multimedia

Multimedia is the use of several different media to convey information (text, audio, graphics, animation, video, and interactivity). -- http://en.wikipedia.org/wiki/Multimedia (accessed 12/05/2005

Graphics and Multimedia Software

Discovering Computers: 2005. Shelly Cashman Vermaat 2005 p. 150 Fig. 3-21

PIXEL

• Images are made up of pixels• “Short for Picture Element, a pixel is a single point in a

graphic image. Graphics monitors display pictures by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. The pixels are so close together that they appear connected. The number of bits used to represent each pixel determines how many colors or shades of gray can be displayed…”

- http://webopedia.com• Higher the resolution, better the quality

http://webopedia.com

Color Depth (Pixel Depth)

• The amount of information per pixel is known as the color depth– Monochrome (1 bit of information per pixel)– Gray-scale (8 bits of information per pixel)– Color (8 or 16 bits of information per pixel)– True color (24 or 32 bits of information per pixel)

Examples of Color Depth

1-bit depth

16-bit depth8-bit depth

4-bit depth

Data Compression

• Lossless – after a file is compressed, every single piece of information stays (e.g. GIF)

• Lossy – actually loses data in the conversion (e.g. JPEG, MPEG, MP3)

http://searchsmb.techtarget.com/sDefinition/0,,sid44_gci214453,00.html (accessed on 12/05/05)

Graphic Compression

• .bmp – Bit-mapped files – every pixel stored

• .gif– Lossless compression – 8 bit color, good for

clip art

• .jpg– Lossy compression – 24 bit color, good for

photos, decreases quality

GIF/JPEG

GIF: 856 kb jpeg: 571 kb

GIF/JPEG

•

• Advantages of GIF files– GIF is the most widely supported graphics format on the Web – GIFs of diagrammatic images look better than JPEGs

•

• Advantages of JPEG images– Huge compression ratios mean faster download speeds – JPEG produces excellent results for most photographs and

complex images

http://www.webstyleguide.com/index.html

Sound Formats

Format Description

WAV Developed for Windows, 8 or 16 bit resolution, stereo or mono, wide range of sampling rates, requires Microsoft Media Player on system

AIFF, AIF Developed for Macintosh, 8 or 16 bit resolution, stereo or mono, wide range of sampling rates

AU Developed for Unix, 8 bit resolution, mono, 8 bit sampling rates

MPEG Primarily used for video clips, very effective compression algorithm allowing whole music recordings to be transferred - .mp3 is recent standard

RealAudio Media that is processed and played as it is downloaded Requires installing RealAudio, known as streaming

MIDI Limited to synthesizers and music files. Much smaller than other files. Stores instructions, not samples.

Multimedia on Web

• Animation– http://tradingroom.bentley.edu/index.html

• Streaming Audio– .rm

• Video– Download movies (Movielink)– video compression – mpeg2

• Streaming Video

Plug-Ins

• An add-on for the visitors browser that allows the browser to display additional types of content.www.summary.net/manual/glossary.html

Rules of Thumb: Creating Smart Art

• Use ready-made graphics (clip art) when available and appropriate

• Honor copyright laws (buy protected work or use copyright-free clip art)

• Protect your own work by including the copyright symbol