Digital Media

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Chapter 7

• Digital Media

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Bitmap Graphics--Definition

• Grid of dots
• Each dot is stored as a binary number

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Uses of Bitmap Graphics

• Cartoons in video games
• Clip-art
• 3-D graphics software
• Digital Cameras
• E-mail photos

• Typical Software
• Microsoft Paint
• Adobe Photoshop

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Bitmap Image Resolution

• Resolutiondimensions of grid that forms image
• of vertical and horizontal pixels
• 150 x 100 pixels
• Resolutiondensity of pixels
• Megapixelstotal of pixels in graphic

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Resolution can be affected by size

• Enlarging bitmap adds pixels by averaging colors
  of nearby pixels
  
• Pixelatedundesirable bitmap appearance

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Bitmap Color Depth

• of colors that can be used in an image
• Monochrome

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True color bitmap (24-bit)

• 16.7 colors
• Each pixel requires 3 bytes of storage

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How does color palette work?
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Grayscale Color Palette

• Displays image using 256 shades of gray

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Bitmap Graphic Formats

• BMPnative format for Windows
• PCXgraphics format for early personal computers
• TIFF (Tag Image File Format)independent format
  used by scanners and digital cameras

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Bitmap Graphics Formats

• JPEGgraphics format with built-iin compression
• GIFlimited to 256 colors
• PNG48 bit true color
• Compresses without losing data
• Public domain format

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Vector Graphics

• Program for re-creating a stored picture
• Doesnt store color values
• Stores instructions to create each shape, size,
  position and color for each object in image

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Vector Graphics
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Vector Graphics Formats

• Picture has flat, cartoon-like quality
• .wmf
• .dxt
• .mgx
• ,eps
• .pict
• .cgm

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Comparison of Vector and Bitmap
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Creating Vector Graphics

• Digitizing tablet
• Drawing software

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Converting Vector to Bitmap

• Rasterization works by superimposing a grid
  over a vector image, and determining the color
  for each pixel
  
• Once converted, the resulting graphic no longer
  has the qualities of a vector graphic
  

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3-D Graphics

• Stored as set of instructions
• Wireframe sets outline of graphic
• Renderingcovers wireframe with surface color and
  texture

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Tools for 3-D Graphics

• Software
• Autocad
• TruSpace
• High-end computer with high resolution monitor,
  enhanced graphics cards, lots of memory

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Animating Graphics

• 3-D graphics can be animated to produce special
  effects
  
• PIXAR
• Dreamworks
• Can be done on home computer with software

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Desktop Video

• Videos designed for play on computer
• Video stored as series of frames
• Framestill picture
• Frame rate-- of frames per second
• Feature films24 frames per second
• Desktop video15 frames per second

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What software do I need?

• Quicktime
• Windows Media Player

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Video Formats
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Web-based Video

• Streaming videosends small part of video to your
  computer and begins to play
  
• Web continues to send parts of file until video
  ends

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Digital Sound Waveform Audio

• Digital representation of sound
• Music
• Voice
• Sound effects
• Computer needs sound card

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Waveform Formats

• Wave (.wav) created by Windows
• Audio Interchange Format (.aif) created by
  Apple
  
• RealAudio (.ra) proprietary format created by
  RealNetworks
  
• MP3 (.mp3) MPEG format, popularized by Napster

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MP3

• compressed waveform audio format that stores
  digitized music, vocals, and narration in such a
  way that the sound quality is good, but file size
  remains relatively small
• CD ripper grabs tracks from audio CD
• MP3 encoder converts Wave file into MP3 format
• MP3 files can be stored anywhere or relocated to
  a portable MP3 player
  

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MIDI MusicMusical Instrument Digital Interface

• Synthesized sound artificially created sound
• MIDI or synthesized speech
• MIDI sequence encoded music stored as .mid,
  .cmf, or .rol
  
• Most sound cards are equipped to capture data
  from a MIDI instrument
  
• Wavetable set of pre-recorded musical
  instrument sounds

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Speech Reproduction

• Speech synthesis process by which machines
  produce sound that resembles spoken words
  
• Speech recognition (or voice recognition)
  ability of machine to understand spoken words
  

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Speech Synthesis

• Phonemes basic sound units strung together by
  speech synthesizers
  
• Text-to-speech software generates sounds that
  are played through your computers standard sound
  card
  
• Speech synthesis is a key technology in wireless
  communication
  

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Speech Recognition

• Speech recognition software analyzes the sounds
  of your voice and converts them to phonemes
  
• Next, the software analyzes the content of your
  speech it compares the phonemes to the words in
  a digital dictionary
  
• Speech recognition software can be integrated
  with word processing software so that you can
  enter text by speaking into a microphone