Digital Media Chapter 8. 8 Chapter 8: Digital Media2 Chapter Contents Section A: Digital Sound Section B: Bitmap Graphics Section C: Vector and

Digital MediaDigital Media

Chapter 8Chapter 8

Chapter 8: Digital Media 2

8 Chapter Contents

Section A: Digital Sound Section B: Bitmap Graphics Section C: Vector and 3-D Graphics Section D: Digital Video Section E: Digital Rights Management


8SECTION A

Digital SoundDigital Sound Digital Audio Basics Portable Audio Players MIDI Music Speech Recognition and Synthesis


8 Digital Audio Basics

Digital representation of sound



Sampling rateSampling rate refers to number of times per second that a sound is measured



Sound cardsSound cards are responsible for transforming bits stored in an audio file into music, sound effects, and narrations– Digital Signal Processor (DSP)


8 Waveform Audio

The most popular waveform audio formatswaveform audio formats (a.k.a., digital audio) include AAC, AIFF, MP3, RealAudio, Wave, and WMA

Audio or media player software allows you to record and play waveform audio files

You can embed waveform files into a Web page and/or other types of documents


8 MIDI Music (Synthesized Sound)

MIDI (Musical Instrument Digital Interface) specifies a standardstandard way to store music data for synthesizerssynthesizers, electronic MIDI instrumentsMIDI instruments, and computerscomputers

MIDI-capable sound cards contain a wavetable– Set of prerecordedprerecorded musical instrument sounds

Does not produce high-quality vocals Does not have full resonance of “real” sound


8 MIDI Music

Music composition softwareprovides tools for entering notes, specifying instruments, printing sheet music, and saving compositions in formatssuch as MIDI.


8 Speech Recognition and Synthesis

Speech synthesisSpeech synthesis is the process by which machines produce sound resembling spoken words– Text-to-speech software

Speech recognitionSpeech recognition refers to the ability of a machine to understand spoken words– Speech recognition software


8SECTION B

Bitmap GraphicsBitmap Graphics Bitmap Basics Scanners and Cameras Image Resolution Color Depth and Palettes Image Compression Bitmap Graphics Formats


8 Bitmap Graphics

Viewed as a grid of dots– Color and intensity of each dot is stored as a

binary number (commonly 24 bits)


8 Scanners and Cameras

Graphics softwareGraphics software is used to modify or edit bitmap graphics– Modify individual pixels (dots) to

• Retouch photographs• Wipe out red eye• Erase rabbit ears

Often require quite a lot of storage and memory space


8 Image Resolution

Expressed as the number of horizontal and vertical pixels– Higher resolutions contain more data (larger file

size) and are higher quality

Bitmaps do not have a fixed physical size


8 Image Resolution

When you increase the resolutionincrease the resolution of a bitmap, pixel interpolationpixel interpolation may occur– Some images may appear pixelated (grainy)


8 Color Depth and Palettes Color depthColor depth is the number of colors available for

use in an image– Monochrome bitmap

Increasing color depth increases file size– True Color bitmap (24-bit bitmap)– 32-bit bitmap

Color palettesColor palettes are used to control color depth– Grayscale palette– System palette– Web palette


8 Color Depth and Palettes


8 Image Compression

Any technique that recodes datarecodes data in an image file so it contains fewer bits– LosslessLossless compression– LossyLossy compression

File compression utility


8 Bitmap Graphic Formats


8SECTION C

Vector and 3-D GraphicsVector and 3-D Graphics Vector Graphics Basics Vector-to-Bitmap Conversion Vector Graphics on the Web 3-D Graphics


8 Vector Graphic Basics

Contain instructionsinstructions for re-creating a picture



Vector graphics resize betterresize better than bitmaps Vector graphics usually require less storageless storage

space than bitmaps Vector graphics are not usually as realisticnot usually as realistic as

bitmap images It is easier to edit an objecteasier to edit an object in a vector

graphic than an object in a bitmap graphic




8 Vector-to-Bitmap Conversion RasterizationRasterization

superimposes a grid over a vector image and determines the color for each pixel

Tracing softwareTracing software locates the edges of edges of objectsobjects in a bitmap image and converts the resulting shapes into vector graphic objects


8 3-D Graphics

Stored as a set of instructionsinstructions– Contain locations and lengths of lines forming a

wireframewireframe

RenderingRendering covers a wireframe with surface color and texture

Ray tracingRay tracing adds light and shadows to a 3-D image


8 3-D Graphics

3-D graphics softwareprovides tools for drawinga wireframe and thenspecifying colors andtextures for rendering.


8SECTION D

Digital VideoDigital Video Digital Video Basics Producing Video Footage Video Transfer Video Editing Video Output Desktop, PDA, and Web Video DVD-Video


8 Digital Video Basics

Uses bits to store color and brightness data for each video frame

Different kinds of digital videos:– Desktop video– Web-based video– DVD-video– PDA video


8 Digital Video Basics Consider the same issues as

with still video:– Resolution of each frame– Color depth of each frame

Added issue to consider is number of frames per second that are captured– More frames, smoother video– More frames, more storage

required (compression?)


8 Video Output


8 Video Output

Chapter 8 CompleteChapter 8 Complete

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Digital Media Chapter 8. 8 Chapter 8: Digital Media2 Chapter Contents Section A: Digital Sound Section B: Bitmap Graphics Section C: Vector and