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Advanced Multimedia and Graphics Dr. Serhan Dagtas 12:15-1:30 pm Tue & Thu Introduction Introduction to the course Outline, objectives, material, etc. Introduction to multimedia Course Outline Introduction to various media types; still images, video, audio, speech, text, graphics

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Advanced multimedia and graphics l.jpg
Advanced Multimedia and Graphics

  • Dr. Serhan Dagtas

    • 12:15-1:30 pm Tue & Thu


Introduction l.jpg
Introduction

  • Introduction to the course

    • Outline, objectives, material, etc.

  • Introduction to multimedia


Course outline l.jpg
Course Outline

  • Introduction to various media types; still images, video, audio, speech, text, graphics

  • Acquisition

  • Compression techniques

  • Analysis and indexing of multimedia content

  • Multimedia retrieval

  • Storage

  • Applications


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Course Objectives

  • Understand the basics of multimedia systems

  • Store, process, and present multimedia data

  • Image, audio, and video indexing & retrieval

  • Work on research projects

  • Computer graphics and virtual reality


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Course Materials

  • Textbooks

    • Mutimedia Fundementals Vol. I,

    • Multimedia Comm. Systems

    • Handouts and web material


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Exams and projects

  • Exams

    • Midterm

    • Final

  • Projects

    • 3-5 assignments

    • Group project


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Policies

  • Reading

    • Read the chapters

    • Assignments may not be from lecture

  • Attendance is expected


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Multimedia

  • Media (plural of medium)

    • Virtually any means of conveying information

    • Mostly text, audio, images, video

    • Also music, raw data, graphic objects, etc.

  • Multimedia

    • More than one media type simultaneously manipulated


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Multimedia Information Systems

  • Storage, Retrieval, Management and

    Analysis of information in any form

    • Images

    • Video

    • Audio

    • Graphics, charts, etc.

    • Text

    • Data


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multiMEDIA what?

  • Medium (media): A means by which information is perceived… Or: A means of affecting or conveying something (information)

“Multimedia” is an adjective!


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Multimedia Information Systems

  • The confluence of several technologies

  • Digital signal processing

  • Image processing

  • Computer graphics

  • Digital Video technology

  • Visual interactive languages

  • Advanced databases

  • Operating systems

  • Computer networks


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Some Enabling Factors

  • Optical disc technology

    • large volumes

    • preserve quality

  • Shift from analog to digital processing

    • high resolution image

    • high fidelity audio


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Analog Video

Digital Video

  • loss of quality in copying

  • cannot be annotated

  • consumers cannot edit

  • duplication without loss

  • index, search, editing

  • fast random access

  • high quality playback

  • interactive


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Enabling Factors (cont’d)

  • Fiber optics technology

    • high bandwidth

    • accuracy

    • speed

  • Fast specialized processors

    • audio boards

    • video boards

  • Better software,

    • real-time OS

    • codec (software only)



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Properties of Multimedia System

  • Combination of Media

    • Is any combination of media a multimedia?

  • Independence

    • Tightly coupled media are not considered multimedia, e.g., a computer controlled video recorder stores audio and video but they are tightly connected

  • Computer supported integration

  • Communication systems


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Continuous vs. Discrete

  • Discrete media

    • time-independent: text and graphics

  • Continuous media

    • time-dependent: sound and full motion video


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Analog vs. Digital

  • Analog

    • Media represented using real values

  • Digital

    • Media represented using discrete values

      • (integers, quantized numbers, floating point representations)


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Sampled media

  • Sampled media

    • Represented by discrete points (which may be real valued)

  • Notice:

    • Sampled does not imply Digital


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Sampling

Sampling - simply taking voltage readings at fixed points in time

Uniform sampling – sampling at regular intervals


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Digital Conversion

  • Given voltage readings at points in time:

    • Convert the readings to digital

  • Options for digital representation:

    • Integers

    • Floating point values


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We’ll focus on...

  • Digital sampled media

  • But…

    • We have to understand the underlying continuous media...


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An Overview of Media Types

We will look at:

  • text

  • Image

  • Sound

  • Video


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Text

  • Plain text:

    • alphanumeric characters

    • Most common representation is ASCII

  • Structured text

    • Text documents are structured (title, sections, …)

    • There are many standards and formats:

      • Word processor formats

      • LaTex, PDF


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Text Compression

  • Compression is either lossy or lossless

  • Text compression is lossless

  • Text compression uses the fact that some characters and phrases appear more often than others


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Text compression: Huffman coding

  • Idea: assign fewer bits to symbols that appear more often and more bits to symbols that are less often

  • Example:

    • Assume a file with 1000 characters

    • Characters are e, t, x, and z

    • Probability of occurrence 0.8, 0.16, 0.02, and 0.02

    • In normal coding we need 2 bits for each symbol  2000 bits for the entire file

    • Using Huffman: 1 for e, 01 for t, 001 for x, and 000 for z

    • Total number of bits = 1000(1*.8+2*.16+3*.02+3*.02) = 1240


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Text compression: run length coding

  • Directly reduce the number of repeating characters

  • A run of any length is represented by: Sc, X, C

    • Sc special character

    • X is the repeated character

    • C is the character count


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Represent the phrase by its token

Input

file

Yes

Phrase

No

add phrase to dictionary and

generate a token

Did it appear

before?

Text compression: Lampel-Ziv-Welch (LZW)

  • Idea: build a dictionary of phrases from the input file.


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LZW example

  • Assume a file with 10,000 characters

  • If we use 8 bits for each character, we need 80,000 bits for the file

  • Suppose the file has 2000 words or phrases out of which 500 are distinct

  • We can use 9 bit tokens for each word or phrase  total number of bits is 18,000 bits


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Image

  • human and computer vision

  • Vision

    • to see an image and to understand its contents

    • capturing, analysis, and extracting features

  • Computer vision/image processing

    • intensity levels

    • resolution

    • distances and areas

    • the role of color

  • Images vs. Graphics

    • images are captured, graphics are created.

    • images are sequences of picture elements, graphics are a series of commands.

    • graphics may be converted into (synthetic) images


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REAL

WORLD

IMAGE

Vision, Image Processing and Visualization

Photography

Image

Processing

Computer

Vision

Computer

Graphics/

Visualization

SCENE

DESCRIPTION


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What kind of images…?

  • Face photos: Mug shots

  • Finger prints

  • CAT-scan data

  • News photos (general. Usually accompanied with explanatory text)

  • Surveillance (semi-specific domain,we may or may not know what to look for).

  • Video segments

    • Movies:general

    • surveillance

    • News broadcast

    • Sports


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Summary

  • Multimedia

  • Multimedia information systems

  • Enabling factors

  • Continuous vs. discrete

  • Analog vs. digital

  • Text

  • image


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