Multimedia tech.sec a & b

Multimedia technology

chinushanu

Basics of Multimedia Technology
• Multimedia is media and content that uses a combination of
different content forms.
• Multimedia includes a combination of text, audio, still
images, animation, video, or interactivity content forms.
• Basic multimedia and communications technology are two terms, which
can be said to go hand in hand with each other. For instance, multimedia
is a means of communication and communication relies on aspects of
multimedia as the basis of its existence.
Basic Multimedia
• Basic multimedia refers to a number of varied technologies that allow
both visual and audio media to be combined in new ways for the purpose
of communicating. The term multimedia often refers to computer
technologies and its applications include entertainment, education and
advertising.
• The majority of PC’s constructed today are capable of multimedia as they
include a CD-ROM or DVD drive and possess a good sound and video card
which is often built into the motherboard.
• The term multimedia also describes a number of dedicated media
appliances such as MP3 players, digital video recorders (DVR’s), advanced
wireless devices, public video displays and interactive television.

Communications Technology
• Communication with regards to computing world
refers to the transmission of data from one
computer to another from one device to
another.
• A communications device therefore is any
machine that assists data transmission. Examples
of communication devices include modems
cables and ports.
• Programs, which allow transmission of data, are
known as communications software. Therefore
communications technology refers to the activity
of designing and constructing and maintaining
communication systems

Computer
• A computer is a programmable machine. The two principal characteristics
of a computer are: it responds to a specific set of instructions in a well-
defined manner and it can execute a prerecorded list of instructions
(a program).
Modern Computers Defined
Modern computers are electronic and digital. The actual machinery --
wires,transistors, and circuits -- is called hardware; the instructions
and data are called software.
• All general-purpose computers require the following hardware
components:
• memory: enables a computer to store, at least temporarily, data and
programs.
• mass storage device: allows a computer to permanently retain large
amounts of data. Common mass storage devices include disk
drives and tape drives.
• input device: usually a keyboard and mouse, the input device is the
conduit through which data and instructions enter a computer.
• output device: a display screen, printer, or other device that lets you see
what the computer has accomplished.
• central processing unit (CPU): the heart of the computer, this is the
component that actually executes instructions.

communication and entertainment
What is communication:-
• Art of getting your message across effectively
through:
• Spoken words-first & simplest way
• Body language-can make or mar
• Written words-reflects importance
• Visuals-leaves greatest impact

Types & methods
written Letter,memos,reports…

spoken Conversations,interviews,phone
calls,requests…

Gestures Facial expressions,actions,voice
tone,silence

visuals Photograph,videos,painting,film…

Multimedia Television,newspaper,magazines,internet…

Multimedia an introduction

• Multimedia comes in many different formats.
It can be almost anything you can hear or see.
• Examples: Pictures, music, sound, videos,
records, films, animations, and more.

Multimedia- Definitions

• Multimedia is any combination of digitally manipulated
text, art, sound, animation and video.
• A more strict version of the definition of multimedia
do not allow just any combination of media.
• It requires
– Both continuous & discrete media to be utilized
– Significant level of independence between media
being used
• The less stricter version of the definition is used in
practice.

Multimedia I -2009 Mohammed Dwikat 8

Multimedia- Definitions

• Multimedia elements are composed into a project using
authoring tools.

• Multimedia Authoring tools are those programs that
provide the capability for creating a complete
multimedia presentations by linking together objects
such as a paragraph of text (song), an illustration, an
audio, with appropriate interactive user control.

Multimedia I -2009 Mohammed Dwikat 9

Framework for multimedia systems
Multimedia Framework Overview
• Multimedia architecture
• QNX-provided components
• Extending functionality
Multimedia architecture
• The Multimedia library architecture is modular,
meaning that it consists of units that can be
interchanged with each other to provide only the
functionality you need.
• Each filter can have multiple input and output
channels, so if you have a file format that's interleaved
with more than one data stream, you can have as many
output data channels as the input data stream
contains.

The Multimedia library offers these
benefits:
• In most cases it doesn't require hardware with an FPU to
deliver acceptable performance (although hardware with
an FPU may deliver better performance).
• Its modular design means you include only the media
elements you need in your application, which reduces size
and complexity.
• It allows you to easily write your own codecs to deal with
new multimedia data formats, or to rewrite or replace
existing codecs.
• It can be optimized for memory or CPU performance to suit
a wide variety of hardware.
• It can handle both frame-based (such as MPEG-1 audio)
and streaming (such as MPEG video) data streams.
• It's designed with a simple, intuitive API.

Multimedia Devices
Webcam
• A webcam is a simple digital camera capable of taking video or still images
for transmission over the Internet. Unlike digital cameras (next section),
webcams don’t include storage capabilities.
Most webcams plug into a USB port, but a few have used IEEE 1394 or parallel
ports.
Digital Camera
• Digital cameras have largely replaced film cameras for both amateur and
professional photography.
• Digital cameras transfer images to computers for emailing, printing, or
storage via either flash memory card readers or direct USB port
connections.
MIDI Music and MIDI Ports
• Musical instrument digital interface (MIDI) music is created from digitized
samples of musical instruments that are stored in the ROM or RAM of a
MIDI device (such as a sound card) and played under the command of a
MIDI sequencer. MIDI sequences can be stored as files for future playback,
and can be transferred between sound cards and MIDI-enabled devices
such as keyboards via the MIDI port.

• Sound Card
Sound cards are used to record and play back
analog audio, and most can also play back
digital audio sources as well. When recording
analog audio sources such as CDs, line in or
microphone in, sound cards digitize the audio
at varying sample rates and store files in either
uncompressed forms such as WAV or
compressed forms such as WMA or MP3.

Delivering medium
CD-ROM
• It is also an optical storage and considered the
most common form of packaging for multimedia
products.
• It started out as a read-only technology in which
user could store data once only and access it
many times.
• Recent technology led to a multi-session version
where user can add to the content of a CD and
even fully able to write to the systems.

• CD-ROMs are popularly used to distribute
computer software, including video games and
multimedia applications, though any data can be
stored (up to the capacity limit of a disc).
• Some CDs hold both computer data and audio
with the latter capable of being played on a CD
player, while data (such as software or digital
video) is only usable on a computer (such as ISO
9660 format PC CD-ROMs). These are
called enhanced CDs.

• The Philips CD-i (Compact Disc Interactive) is an
interactive multimedia CD player developed and
marketed by Royal Philips Electronics N.V.
• This category of device was created to provide more
functionality than an audio CD player or game console,
but at a lower price than a personal computer with CD-
ROM drive at the time.
• The cost savings were due to the lack of a hard drive,
floppy drive, keyboard, mouse, monitor (a standard
television was used), and less operating
system software.

The user interface
• System users often judge a system by its
interface rather than its functionality
• A poorly designed interface can cause a user to
make catastrophic errors
• Poor user interface design is the reason why so
many software systems are never used
Graphical user interfaces
• Most users of business systems interact with
these systems through graphical interfaces
although, in some cases, legacy text-based
interfaces are still used

2.1 Multimedia Authoring
• Multimedia authoring: creation of multimedia productions, sometimes
called “movies” or “presentations”.

– we are mostly interested in interactive applications.

– For practicality, we also have a look at still-image editors such as Adobe
Photoshop, and simple video editors such as Adobe Premiere.

• In this section, we take a look at:

– Multimedia Authoring Metaphors
– Multimedia Production
– Multimedia Presentation
– Automatic Authoring

Multimedia Systems (eadeli@iust.ac.ir) 18

Multimedia Authoring Metaphors
1. Scripting Language Metaphor: use a special language to
enable interactivity (buttons, mouse, etc.), and to allow
conditionals, jumps, loops, functions/macros etc. E.g., a
small Toolbook program is as below:
-- load an MPEG file
extFileName of MediaPlayer "theMpegPath" =
"c:windowsmediahome33.mpg";
-- play
extPlayCount of MediaPlayer "theMpegPath" = 1;
-- put the MediaPlayer in frames mode (not time mode)
extDisplayMode of MediaPlayer "theMpegPath" = 1;
-- if want to start and end at specific frames:
extSelectionStart of MediaPlayer "theMpegPath" = 103;
extSelectionEnd of MediaPlayer "theMpegPath" = 1997;
-- start playback
get extPlay() of MediaPlayer "theMpegPath";


2. Slide Show Metaphor: A linear presentation by
default, although tools exist to perform jumps in
slide shows.

3. Hierarchical Metaphor: User-controllable
elements are organized into a tree structure —
often used in menu-driven applications.

4. Iconic/Flow-control Metaphor: Graphical icons
are available in a toolbox, and authoring
proceeds by creating a flow chart with icons
attached (Fig. 2.1):

5. Frames Metaphor: Like Iconic/Flow-control Metaphor;
however links between icons are more conceptual,
rather than representing the actual flow of the
program (Fig. 2.2):

Fig. 2.2: Quest Frame


6. Card/Scripting Metaphor: Uses a simple index-card
structure — easy route to producing applications that
use hypertext or hypermedia; used in schools.

Fig. 2.3: Two Cards in a Hypermedia Stack


7. Cast/Score/Scripting Metaphor:

• Time is shown horizontally; like a spreadsheet: rows,
or tracks, represent instantiations of characters in a
multimedia production.

• Multimedia elements are drawn from a cast of
characters, and scripts are basically event-procedures
or procedures that are triggered by timer events.

• Director, by Macromedia, is the chief example of this
metaphor. Director uses the Lingo scripting language,
an object-oriented event-driven language.


Uses of multimedia authoring programs

• Create multimedia titles
• Create interactivity
• Design screen layouts
• Produce content with paint, text, and
animation tools
• Incorporate text, sound, video, animation,
and graphics
• Create hyperlinks

Types of Multimedia Authoring Programs

Authoring programs are categorized mainly by the way they work.

• Electronic slide show • Card/book metaphor
 Advantages:  Advantages:
• Inexpensive to create • Easy to learn
• Easy to use • Direct relationship
between what is on a
• Easy to learn card or page and what
• Templates available is displayed on a screen.
that can be customized  Disadvantages:
 Disadvantage: • Usually run on one
platform
Predominately linear
presentations • Usually limited
compared to other
authoring programs.

Types of Multimedia Authoring Programs
(Continued)

• Icon-based authoring • Time-based authoring
programs use programs are like
flowchart to represent movies that play until
content or event. some action causes it
to stop.
Advantage:
Flow of content or event Advantage:
easily seen.
Disadvantages: Users can branch to
• Less insightful different parts of
• Difficult to learn movies
• Expensive

• Uses of multimedia authoring programs
 Create multimedia titles
 Create interactivity
 Design screen layouts
 Produce content with paint, text, and animation tools
 Incorporate text, sound, video, animation, and graphics
 Create hyperlinks
• Types of multimedia authoring programs
 Electronic slide show
 Card/book metaphor
 Icon-based
 Time-based
 Web-based
 Programming languages

Professional development tools

• WebinarsOrganizations that deliver webinars on topics relevant to SNAP-Ed
providers.
• CalendarUpcoming Conference Calendar
• Online TrainingOnline training resources, including modules and courses, for
nutrition educators.
• Conference ProceedingsSelected highlights from recent conferences. Materials are
either from SNAP-Ed specific sessions or are applicable to SNAP-Ed providers.
• Icebreakers and Training ToolsResources for SNAP-Ed providers working in group
settings.
• Social MarketingDefinitions, overviews, examples, research, guides and other
resources on social marketing.
• EvaluationResources for developing and conducting evaluations of nutrition
education programs.
• Behavior ChangeReports and articles for educators working to promote behavior
change.

Local Area Networks (LANs)
• In IEEE 802 Reference Model for LANs, the functionality of the Data
Link layer is enhanced, and it has been divided into two sublayers:

– - Medium Access Control (MAC) layer:
(a) Assemble or disassemble frames upon transmission or reception.
(b) perform addressing and error correction.
(c) Access control to shared physical medium.

– - Logical Link Control (LLC) layer:
(a) Flow and error control.
(b) MAC-layer addressing.
(c) Interface to higher layers. LLC is above MAC in the hierarchy.

Li & Drew 29

Internt
• The Internet (or internet) is a global system of
interconnected computer networks that use
the standard Internet protocol suite (often
called TCP/IP, although not all applications use
TCP) to serve billions of users worldwide.
• It is a network of networks that consists of
millions of private, public, academic, business,
and government networks, of local to global
scope, that are linked by a broad array
of electronic, wireless and optical networking
technologies.

World wide web
• The World Wide Web (abbreviated
as WWW or W3, commonly known as the Web),
is a system of interlinked hypertext documents
accessed via the Internet.
• The documents are formatted in a markup
language called HTML (HyperText Markup
Language) that supports links to other
documents, as well asgraphics, audio, and
video files.
• This means you can jump from one document to
another simply by clicking on hot spots. Not all
Internet servers are part of the World Wide Web.
• World Wide Web is not synonymous with the
Internet.

The Asynchronous Transfer Mode
•
(ATM)
(ATM) is, according to the ATM Forum,
"a telecommunications concept defined
by ANSI and ITU (formerly CCITT) standards for carriage of a
complete range of user traffic, including voice, data,
and video signals,“
• ATM provides data link layer services that run over a wide
range of OSI physical Layer links. ATM has functional similarity
with both circuit switched networking and small packet
switched networking.
• ATM is a technology that provides a single platform for the
transmission of voice, video, and data at specified quality of
service and at speeds varying from fractional T1, i.e., nX64
Kbps, to Gbps. Voice, data and video are currently transported
by different networks.

(ADSL)
• Asymmetric digital subscriber line (ADSL) is a type
of digital subscriber line technology, a data
communications technology that enables faster data
transmission over copper telephone lines than a
conventional voiceband modem can provide. It does
this by utilizing frequencies that are not used by a
voicetelephone call.
• At the telephone exchange the line generally
terminates at a digital subscriber line access
multiplexer (DSLAM) where another frequency splitter
separates the voice band signal for the
conventional phone network.
• Data carried by the ADSL are typically routed over
the telephone company's data network and eventually
reach a conventional Internet Protocol network.

ADSL is:
■ Asymmetric, because data transmission is faster downstream to the
subscriber than upstream from the subscriber,
■ Digital, because even voice and video are digitised before they are
transmitted as modulated analogue representations of digital data,
■ Subscriber Line, because data is carried over a single twisted pair copper
‘loop’ to the subscribers premises.

Why use ADSL?
Typically Web browsing involves downloading five times as much data as it
transmits, so customers do not need a high bi-directional transmission speed.
ADSL also allows service providers to limit web hosting on subscriber lines, or
sell it separately; a web server cannot run effectively over ADSL.

What is a Multimedia DBMS?

• A multimedia database management system (MM-DBMS) is a
framework that manages different types of data potentially
represented in a wide diversity of formats on a wide array of media
sources.
• Like the traditional DBMS, MM-DBMS should address requirements:
– Integration
• Data items do not need to be duplicated for different
programs
– Data independence
• Separate the database and the management from the
application programs
– Concurrency control
• allows concurrent transactions

MM Database 35

What is a Multimedia DBMS?

• A multimedia database management system (MM-DBMS) is a
framework that manages different types of data potentially
represented in a wide diversity of formats on a wide array of media
sources.
• Like the traditional DBMS, MM-DBMS should address requirements:
– Integration
• Data items do not need to be duplicated for different
programs
– Data independence
• Separate the database and the management from the
application programs
– Concurrency control
• allows concurrent transactions

MM Database 36

Requirements of Multimedia DBMS (cont.)
• In addition, an MM-DBMS should:
– have the ability to uniformly query data (media data, textual data)
represented in different formats.
– have the ability to simultaneously query different media sources and
conduct classical database operations across them.
query support
– have the ability to retrieve media objects from a local storage device
in a smooth jitter-free (i.e. continuous) manner.
storage support
– have the ability to take the answer generated by a query and develop
a presentation of that answer in terms of audio-visual media.
– have the ability to deliver this presentation in a way that satisfies
various Quality of Service requirements.
presentation and delivery support

MM Database 37

Architecture for Distributed
Multimedia Server
Autonomous Disks

1 2 3 4 5 N

Configuration
Manager

High Speed Network

User Setup 38

Target Features of a Multimedia Server

• Support for a variety of multimedia types and
formats
• Real-time guarantees
• Scalable
• Reliable

39

Web server
 A Web server is a program that generates and
transmits responses to client requests for Web
resources.
 Handling a client request consists of several
key steps:
 Parsing the request message
 Checking that the request is authorized
 Associating the URL in the request with a file name
 Constructing the response message
 Transmitting the response message to the requesting client

WEB SERVERS

Steps in Handling a Client Request
 A Web server proceeds through the following
steps in handling an HTTP request:
 Read and parse the HTTP request message
for example GET the resource /foo.htm
 Translate the URL to a file name
for example the resource be located in the base directory
such as /www, where the URL
http://www.bar.com/foo/index.html corresponds to
the file of www/foo/index.html
 Determine whether the request is authorized
 Generate and transmit the response that includes
header to show the status information
Web Protocols and Practice

Vector graphics
• Vector graphics is the use
of geometrical primitives such
as points, lines, curves, and shapes or polygon(s),
which are all based on mathematical expressions,
to represent images in computer graphics.
"Vector", in this context, implies more than a
straight line.
• Vector graphics are based on images made up of
vectors (also called paths, or strokes) which lead
through locations called control points. Each of
these points has a definite position on the x and y
axes of the work plan.

Introduction to 3d Computer Graphics
• 3D computer graphics is the science, study,
and method of projecting a mathematical
representation of 3D objects onto a 2D image
using visual tricks such as perspective and
shading to simulate the eye's perception of
those objects.

3D computer graphic software
• 3Dcomputer graphics software refers to programs used to
create 3D computer-generated imagery.
• 3D modelers allow users to create and alter models via
their 3D mesh. Users can add, subtract, stretch and
otherwise change the mesh to their desire. Models can be
viewed from a variety of angles, usually simultaneously.
Models can be rotated and the view can be zoomed in and
out.
• 3D modelers can export their models to files, which can
then be imported into other applications as long as
the metadata is compatible. Many modelers
allow importers and exporters to be plugged-in, so they can
read and write data in the native formats of other
applications.
• Most 3D modelers contain a number of related features,
such as ray tracers and other rendering alternatives
and texture mapping facilities.

What is Animation?
The word Animation is
generated from word
'anime' which means life.
Animation is the rapid
display of a sequence of
images of 2-D or 3-D
artwork or model
positions in order to
create an illusion of
movement

Beginning of 21st Century

• The animators' drawings and the backgrounds
are either scanned into or drawn directly into
a computer system.
• Various software programs are used to color
the drawings and simulate camera movement
and effects
• The final animated piece is output to one of
several delivery media, including traditional
35mm film and newer media such as digital
video

Examples of traditionally animated feature
films

(animation techs).1Hand drawn
animation
• Traditional animation, also referred to as
classical animation, cel animation, or hand-
drawn animation, is the oldest and historically
the most popular form of animation. In a
traditionally-animated cartoon, each frame is
drawn by hand
• Disney used this type of animation, some
animators, even those working in the industry
today, choose to use the traditional drawn
method. Others use computer programmes
that simulate the traditional method such as
photoshop

2.Stop Motion Animation
Stop-motion animation, is the term used to describe animation created by physically manipulating
real-world objects and photographing them one frame of film at a time to create the illusion of
movement.

There are many different types of stop-motion animation, usually named after the type of media used
to create the animation, these include:
• Cutout animation
• Claymation animation
• Model animation (like the classic King-Kong)
• Object animation
• Puppet animation

3.Cutout Animation
Cutout animation is a unique technique for producing animations
using flat characters, props and backgrounds cut from materials
such as paper, card, stiff fabric or even photographs.

The world's earliest known animated feature films were cutout
animations (made in Argentina by Quirino Cristiani as early as
1917)

Angela Anaconda is a contemporary example of the use of cutout
animation. The programme combines black-and-white photographs
with cutout-style CGI animation.
http://www.youtube.com/watch?v=utgXR6k-P1s

4.Clay animation

• In clay animation, which is one
of the many forms of stop
motion animation, each object
is sculpted in clay or a similarly
pliable material such as
Plasticine, usually around a
wire skeleton called an
armature.

5.Computer animation
• Computer animation encompasses a
variety of techniques, the unifying idea
being that the animation is created
digitally on a computer.

• The term covers 2D animation using
Flash to the CGi techniques used in
Pixar’s many successful films.

http://www.youtube.com/watch?v=D5YmIS5
7J9E

6.Drawn on film animation
• Drawn on film animation (also known as "direct animation", or "animation without camera") is
an animation technique where footage is produced by creating the images directly on film stock,
as opposed to any other form of animation where the images or objects are photographed frame
by frame with an animation camera

• There are two basic methods to produce animation directly on film. One starts with blank film
stock, the other one with black (already developed) film. On blank film the artist can draw, paint,
stamp, or even glue objects. Black film (or any footage) can be scratched, etched, sanded, or
punched. Any tool the artist finds useful may be used for this, and all techniques can be
combined endlessly. The frame borders may be observed or completely ignored, found footage
may be included, any existing image might be distorted by mechanical or chemical means.

Shading
• Shading refers to depicting depth
perception in 3D models or illustrations by
varying levels of darkness.
• Anti-aliasing-it is a process used to remove
jagged edges in computer graphics. The
blurring of hard edges to create the
appearance of smoothness. Most commonly
used with respect to graphics, especially text.

Morphing
• Morphing is a special effect in motion
pictures and animations that changes (or
morphs) one image into another through a
seamless transition.
• Most often it is used to depict one
person turning into another through
technological means or as part of a fantasy or
surreal sequence.
• Traditionally such a depiction would be achieved
through cross-fading techniques on film. Since
the early 1990s, this has been replaced by
computer software to create more realistic
transitions.

video on demand
• Video on Demand (VOD) or Audio and Video on
Demand (AVOD) are systems which allow users
to select and watch/listen
to video oraudio content on demand.
• IPTV technology is often used to bring video on
demand to televisions and personal
computers. Catch up TVis a form of video on
demand.
• Some airlines offer AVOD as in-flight
entertainment to passengers through individually
controlled video screens embedded in seatbacks
or armrests or offered via portable media players.

(Sec-B) Image Compression &
Standards
Making still images-Still images are visual
representations that do not move.
• Still images, however, allow the content creator
to convey information which can be more freely
interpreted by the user.
• Still images may be the most important element
of a multimedia project.
• The type of still images created depends on the
display resolution, and hardware and software
capabilities.

Types of still images
Still images are generated in two ways:
– Bitmaps.
– Vector-drawn graphics
• Bitmaps-It is derived from the words ‘bit’, which means
the simplest element in which only two digits are used,
and ‘map’, which is a two-dimensional matrix of these
bits.
• A bitmap is a data matrix describing the individual dots
of an image.
Bitmaps are an image format suited for creation of:
– Photo-realistic images.
– Complex drawings.
– Images that require fine detail.

Bitmaps

Available binary Combinations for
Describing a Color

Bitmaps
Bitmaps can be inserted by:
– Using clip art galleries.
– Using bitmap software.
– Capturing and editing images.
– Scanning images.

The industry standard for bitmap painting and
editing programs are:
• Adobe's Photoshop and Illustrator.
• Macromedia's Fireworks.
• Corel's Painter.
• CorelDraw.
• Quark Express.

Using Clip Art Galleries
• A clip art gallery is an assortment of graphics,
photographs, sound, and video.
• Clip arts are a popular alternative for users
who do not want to create their own images.
• Clip arts are available on CD-ROMs and on the
Internet.

Capturing and Editing Images -imp
Image editing programs enable the user to:
– Enhance and make composite images.
– Alter and distort images.
– Add and delete elements.
– Morph (manipulate still images to create animated transformations).
Scanning images-Users can scan images from conventional sources and
make necessary alterations and manipulations.

Vector-Drawn Graphics
• Applications of vector-drawn images.
• How vector-drawn images work?
• Vector-drawn images v/s bitmaps.
Applications of Vector-Drawn Images-
– Computer-aided design (CAD) programs.
– Graphic artists designing for the print media.
– 3-D animation programs.
– Applications requiring drawing of graphic shapes.

How Vector-Drawn Images Work
• A vector is a line that is described by the
location of its two endpoints.
• Vector drawing makes use of Cartesian co-
ordinates.
• Cartesian coordinates are numbers that
describe a point in two or three-dimensional
space as the intersection of X, Y, and Z axis.

Vector-Drawn Images v/s Bitmaps
• Vector images use less memory space and have a
smaller file size as compared to bitmaps.
• For the Web, pages that use vector graphics in plug-ins
download faster, and when used for animation, draw
faster than bitmaps.
• Vector images cannot be used for photorealistic
images.
• Vector images require a plug-in for Web-based display.
• Bitmaps are not easily scalable and resizable.
• Bitmaps can be converted to vector images using
autotracing.

Computer &Color Models
Models used to specify color in computer terms
are:
– RGB model - A 24-bit methodology where color is specified in terms of
red, green, and blue values ranging from 0 to 255.
– HSB and HSL models – Color is specified as an angle from 0 to 360
degrees on a color wheel.
– Other models include CMYK, CIE, YIQ, YUV, and YCC.

Color Palettes
• Palettes are mathematical tables that define
the color of pixels displayed on the screen.
• Palettes are called ‘color lookup tables’ or
CLUTs on Macintosh.
• The most common palettes are 1, 4, 8, 16, and
24-bit deep.
Dithering:
– Dithering is a process whereby the color value of each pixel is changed to the
closest matching color value in the target palette.
– This is done using a mathematical algorithm.

Vector drawing
• Vector graphics is the use
of geometrical primitives such
as points, lines, curves,
and shapes or polygon(s), which are all based
on mathematical expressions, to
represent images in computer graphics.
"Vector", in this context, implies more than a
straight line.

3D drawing
• whenever we look a things they are in three
dimensions we see thgs in length height and
width. Drawings that are created to represent
the three dimensions is called a 3-D drawing
• A 3 dementional shape, object or thing you
draw upon a peice of paper that shows you
the perspective and shading used to help
make the drawing more realistic.

3D Rendering
• The process of taking the mathematical model of the
world and producing the output image.
• The core of the rendering process involves projecting
the 3D models onto a 2D image plane.

Types of Rendering Algorithms
• Two general approaches:

– Pixel-oriented rendering:
• Ray tracers

– Polygon-oriented rendering:
• Scan-line renderers

1.Ray tracers
• Operates by tracing
theoretical light rays
as they intersect
objects in the scene
and the projection
plane.

2.Scan-line renderers
– Operate on an object-by-object basis, directly
drawing each polygon to the screen.
– Requires all objects – including those modeled
with continuous curvature – to be tessellated into
polygons.
– Polygons are eventually tessellated into pixels.

JPEG Introduction - The background
• JPEG stands for Joint Photographic Expert Group
• A standard image compression method is needed to
enable interoperability of equipment from different
manufacturer
• It is the first international digital image compression
standard for continuous-tone images (grayscale or color)
• The history of JPEG – the selection process

JPEG objective-
• “very good” or “excellent” compression rate,
reconstructed image quality, transmission rate
• be applicable to practically any kind of continuous-tone
digital source image
• good complexity
• have the following modes of operations:
– sequential encoding
– progressive encoding
– lossless encoding
– hierarchical encoding

JPEG Overview

Source encoder compressed
Encoder descriptors symbols entropy
image data statistical image data
model encoder
model

model entropy
tables coding tables

The basic parts of an JPEG encoder

JPEG
• Architecture of standard
• Forward transform
• Quantization
• Entropy coding
– DC coefficient
– AC coefficients

Source Forward Entropy Compressed
image data transform Quantization encoding image data

JPEG
Source Entropy Compress
image Forward Quantizati encoding ed image
data transform on data

• Forward transform

1. Level shifted 2 p 1
2. Divided into blocks of 8*8 pixels
3. Forward DCT:

1 2j 1i
cos i 0, j 0 ,1,..., N 1
N 2N
C i, j
2 2j 1i
cos i 0 ,1,..., N 1, j 0 ,1,..., N 1
N 2N

JPEG
• Original image
124 125 122 120 122 119 117 118
121 121 120 119 119 120 120 118
126 124 123 122 121 121 120 120
124 124 125 125 126 125 124 124
127 127 128 129 130 128 127 125
143 142 143 142 140 139 139 139
150 148 152 152 152 152 150 151
156 159 158 155 158 158 157 156

JPEG
• DCT coefficients
39 . 88 6 . 56 2 . 24 1 . 22 0 . 37 1 . 08 0 . 79 1 . 13
102 . 43 4 . 56 2 . 26 1 . 12 0 . 35 0 . 63 1 . 05 0 . 48
37 . 77 1 . 31 1 . 77 0 . 25 1 . 50 2 . 21 0 . 10 0 . 23
5 . 67 2 . 24 1 . 32 0 . 81 1 . 41 0 . 22 0 . 13 0 . 17
3 . 37 0 . 74 1 . 75 0 . 77 0 . 62 2 . 65 1 . 30 0 . 76
5 . 98 0 . 13 0 . 45 0 . 77 1 . 99 0 . 26 1 . 46 0 . 00
3 . 97 5 . 52 2 . 39 0 . 55 0 . 051 0 . 84 0 . 52 0 . 13
3 . 43 0 . 51 1 . 07 0 . 87 0 . 96 0 . 09 0 . 33 0 . 01

JPEG
Source Forwa Quantiz Entrop Compr
image rd ation y essed
data transfo encodi image
rm ng data
• Quantization
– Quantization table ij
l ij 0 .5
Q ij

– Zigzag scan

JPEG
• Quantization table

16 11 10 16 24 40 51 61
12 12 14 19 26 58 60 55
14 13 16 24 40 57 69 56
14 17 22 29 51 87 80 62
18 22 37 56 68 109 103 77
24 35 55 64 81 104 113 92
49 64 78 87 103 121 120 101
72 92 95 98 112 100 103 99

JPEG
Source Forwar Quantiza Entrop Compre
image d tion y ssed
data transfor encodin image
m g data

• Entropy encoding
• DC coefficient and AC coefficients are coded differently
• DC coefficient
– Encode the difference
– Huffman code unmanageable
Category Possible values
0 0
1 -1 1
2 -3 -2 23
3 -7 -6 -5 -4 4567
– First bits to define the category and other bits to define the element in
the category

JPEG
• AC coefficients
Defined by a certain number of terms:
» Category C that a non zero label falls in
» Z: number of zero since the last non zero label
– Z/C points to a specific code
– Follows by bits to define the element in the category
– +1 code
» EOB stands for End Of Block:
A code after the last non zero value

JPEG
• More accurate image
– Increase the bit rate
– Decrease quantization table elements
• Less accurate image
– Decrease the bit rate
– Increase quantization table elements
• Problem:
Low rate image: « blockiness »

Lossless Predictive Coding

• Prediction up [n] is calculated for x[n] from
previous samples
• e[n] is prediction error, with greatly reduced
statistical dependencies between adjacent
samples
• Entropy coder may assume i.i.d. prediction error
e[n]
• Receiver can reconstruct x[n] without loss for
amplitude-discrete signals
• Much simpler than context-adaptive coder

Graphics interchange format
• The Graphics Interchange Format (GIF; /ˈ dʒɪf/ or /ˈ ɡɪf/) is
a bitmap image format that was introduced by CompuServe in 1987
and has since come into widespread usage on the World Wide
Web due to its wide support and portability.
• The format supports up to 8 bits per pixel thus allowing a single
image to reference a palette of up to 256 distinct colors. The colors
are chosen from the 24-bit RGB color space.
• It also supports animationsand allows a separate palette of 256
colors for each frame. The color limitation makes the GIF format
unsuitable for reproducing color photographs and other images
with continuous color, but it is well-suited for simpler images such
as graphics or logos with solid areas of color.
• GIF images are compressed using the Lempel-Ziv-
Welch (LZW) lossless data compression technique to reduce the file
size without degrading the visual quality

Usage of GIFs
• GIFs are suitable for sharp-edged line art (such as logos)
with a limited number of colors. This takes advantage of the
format's lossless compression, which favors flat areas of
uniform color with well defined edges.
• GIFs can be used to store low-color sprite data for games.
• GIFs can be used for small animations and low-resolution
film clips.
• In view of the general limitation on the GIF image palette to
256 colors, it is not usually used as a format for digital
photography. Digital photographers use image file formats
capable of reproducing a greater range of colors, such
as TIFF, RAW or JPEG

TIFF
• TIFF (originally standing for Tagged Image File Format) is a
file format for storing images, popular among graphic
artists, the publishing industry,]and both amateur and
professional photographers in general.
• As of 2009, it is under the control of Adobe Systems.
Originally created by the companyAldus for use with
"desktop publishing", the TIFF format is widely supported
by image-manipulation applications, by publishing and
page layout applications, by scanning, faxing, word
processing, optical character recognition and other
applications.
• Adobe Systems, which acquired Aldus, now holds the
copyright to the TIFF specification.

BMP
• The BMP file format, also known as bitmap image
file or device independent bitmap (DIB) file format or
simply a bitmap, is a raster graphicsimage file
format used to store bitmap digital images,
independently of the display device (such as a graphics
adapter), especially on Microsoft
Windows and OS/2 operating systems.
• The BMP file format is capable of storing 2D digital
images of arbitrary width, height, and resolution,
both monochrome and color, in various color depths,
and optionally with data compression, alpha channels,
and color profiles.

PNG
• Portable Network Graphics (PNG pron.: /ˈ [2] PING) is
pɪŋ/
a bitmapped image format that employs lossless data
compression.
• PNG was created to improve upon and
replace GIF (Graphics Interchange Format) as an image-file
format not requiring a patent license.
• PNG supports palette-based images (with palettes of 24-
bit RGB or 32-bit RGBA colors), grayscale images (with or
without alpha channel), and full-color non-palette-based
RGB[A] images (with or without alpha channel). PNG was
designed for transferring images on the Internet, not for
professional-quality print graphics, and therefore does not
support non-RGB color spaces

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