Multimedia Basics

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Multimedia Basics

• 2007-02-12

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Analog

• Continuous
• One-to-one correspondence
• Waveform audio

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Digital Graphics

• Pixel Picture Element
• Megapixel ? 1 million pixels
• Three phosphor dots per pixel
• Red, green, blue
• Use numbers to represent a color
• 0255

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Bitmap Graphics

• Raster Graphics
• Maps showing how the pixels should be
• Grayscale graphics
• 8 bits per pixel
• 256 shades of gray
• More than the human eye can distinguish

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Bitmap Graphics

• Realistic color graphics require more memory
• 8-bit color
• Allows 256 different colors
• Photorealistic color (true color)
• 24 bit (32 bit, extra bits for special effects)
• Color depth or bit depth

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Bitmap Graphics

• Resolution the density of the pixels
• Dots per inch (dpi)
• 96 dpi typical screen
• Image-editing tools give unsurpassed control
  over
• textures,
• Shading
• Fine detail

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Bitmap Graphic Formats

• BMP ? Bit Map
• native to Windows,
• supports true color
• Not supported by most browsers
• TIFF ? Tag Image File Format
• Flexible, platform independent
• Scanners, cameras

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Bitmap Graphic Formats

• JPEG ?Join Photographic Experts Group
• You can control the amount of compression
• Supports true color
• GIF ? Graphics Interchange Format
• Limited to 256 colors
• PNG ? Portable Network Graphics
• Successor to GIF, 48 bit color.

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Object-Oriented Graphics

• Vector graphics
• Postscript
• Page description language
• Manipulate objects not pixels
• Easier to edit
• Shapes stored as models
• Smaller file size
• Resize easily

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Animation

• Frames
• Flip-book
• Film movies
• Animator can create key frames and objects
• Computer fills in the in-between frames
• GIF
• Bitmapped
• Some ability for animation

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Animation

• Shockwave Flash Format (SWF)
• Vector graphics looks good on a wide variety of
  displays
• Scalable Vector Graphics (SVG)
• Stores info as text

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Digital Audio

• Audio digitizer
• Samples the wave form
• Sampling rate
• The more samples the better the sound
• Bits per sample
• 8 or 16

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Digital Audio

• Audio CDs is memory intensive
• Sample rate 44 K per second
• Two channels
• Compression
• Removes the redundancy from a file
• Lossless compression
• Zip files
• Decompressed file is identical to the original
  file

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Digital Audio

• Lossy compression
• Better compression ? smaller files
• Some information is lost
• Tolerable in many types of sound
• JPEG
• MPEG
• Stores only the pixels that change from frame to
  frame

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MIDI

• Musical Instrument Digital Interface
• Contains instructions for creating the pitch,
  volume and duration of notes
• More compact than digital audio
• 3 minutes of audio MIDI(10KB) Digital(15 MB)
• Doesnt produce high-quality vocals