Matakuliah
Tahun
: T0732 / Sistem Multimedia
: 2007
Graphics
Pertemuan 4
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa akan
mampu :
• Menunjukkan Penggunaan Gambar pada Aplikasi
Multimedia
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Outline Materi
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What is an Image
Image Media Types
Bitmap Image
Vector Image
3-Dimensional Graphic Models
Working With Graphics
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What is an Image?
• An image is the graphical
and visual representation of
some information that can be
displayed on a computer
screen or printed out
• Images come in a variety of
forms:
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Photographs
Drawings
Paintings
Television and motion pictures
Semantics
Maps, etc.
What is an Image?
• Images play an important
part in multimedia
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Navigation
User interface components
Help systems
Clip art
Opening Screen
Main Menu
Jazz Dive Profile
History
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Contact
Links
Promoted Bands
The
Flairz
Little
Birdy
The
Waifs
John
Butler
Trio
Image Media Types
• Images can be generally divided into two
formats:
– Bitmapped or Raster images
– Draw-type or Vector graphics or Metafile images
• Bitmapped images are stored as an array of
pixels. It represents the image as an array of
dots, called pixels
• Vector graphics are stored as geometric shape
to represent the image (mathematically defined)
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Raster Image
• A pixel is the smallest element of resolution on a
computer screen (Screen Resolution)
• Bitmap  matrix of pixel
• Each pixel can be in a specific colour and each pixel
consists of two or more colors.
• The range of these colours is known as the colour depth.
• Colour depth is measured in bits per pixel
– Remember: a bit (binary digit) is either 1 or 0 and that there are eight bits
in a byte
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Colour depth
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1 bit per pixel = 2 colours (monochrome)
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2 bits per pixel = 4 colours
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4 bits per pixel = 16 colours
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8 bits per pixel = 256 colours
– Generally good enough for colour images
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16 bits per pixel = 65536 colours
– Better quality for photograph-like images, also known as high colour
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24 bits per pixel = >16 million possible colours
– Used to recreate photo realistic images, also known as true colour
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Colour Depth
True Colour (24 bits)
4 bits
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8 bits
1 bit
http://en.wikipedia.org/wiki/Color_depth
Raster Image
• More colour per pixel  bigger image size
• The number of pixels is related to the size of file
that required to store an image.
• Remember, two factors effect the size file bitmap
are:
– Resolution
– Color Depth
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Bitmaps images
Original image
Shown
magnified
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Calculating the size of a raster image
width  height  colour depth
size in bytes 
8
• Where:
– Width of the images measured in pixels
– Height of the images measured in pixels
– Colour depth is the number of bits used for color measured in bits per
pixel
• Remember:
– 1024 bytes = 1 kilobyte (KB)
– 1024 kilobytes = 1 megabyte (MB)
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Example
• A 640 x 480 pixel image in 24-bit colour would require how much
disk space?
640  480  24 7372800
size in bytes 

8
8
 921600 bytes
 900KB
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Type of Compression
Lossless compression :
• Modify the way the data is organized or
represented to reduce storage size.
• No loss in detail;
Example: ‘Run-length Encoding’.
• Original : AAABBBCCCCCCABCABC
• RLE
: 3A3B6C2ABC
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Type of Compression
Lossy compression schemes:
• Try to maximise compression without loss
obvious to human user.
• Remove detail during the compression
• NOTE: repeated compression caused loss in
quality
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Popular bitmap formats
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Microsoft bitmap (.bmp)
– Used in microsoft windows
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TIFF - Tagged Image File Format (.tif)
– Used for faxing images (amongst other things)
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JPEG - Joint Photographic Expert Group (.jpg)
– Useful for storing photographic images
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GIF - Graphics Interchange Format (.gif)
– Used a lot on web sites
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PNG - Portable Network Graphics (.png)
– A new format for web graphics
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PCD – Kodak photo CD
– A new format for store image in a compressed form on a CD
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Advantages and Disadvantages
of using bitmap images
• Advantages
– Convey detail of information quickly
– Real life
• Disadvantages
– Depend on a Resolution
– Effect to the image quality
– Size file is big
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Software to create bitmap images
• Popular PC packages include:
– Microsoft Paint
• Included with microsoft windows
– Microsoft PhotoDraw 2000
• http://www.microsoft.com/office/photodraw/
– Adobe Photoshop
• http://www.adobe.com/products/photoshop/main.html
– Paint Shop Pro
• http://www.jasc.com/psp6.html
– Macromedia Fireworks
• http://www.macromedia.com/software/fireworks/productinfo/
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Software to create raster
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Vector images
• Vector images are stored as the set of graphic
primitives required to represent the image
• A graphic primitive is a simple graphic based on
drawing elements or objects such as shape
– e.g. square, line, ellipse, arc, etc.
• The image consists of a set of commands
(mathematical equations) that are drawn the
object when needed.
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Vector images
• Storing and representing images by mathematical
equations is called vector graphics or Object Oriented
graphics.
• Each primitive object has various attributes that go to
make up the entire image
– e.g. x-y location, fill colour, line colour, line style, etc.
• Example:
– RECTANGLE : rectangle top, left, width, height, color is ( 0, 0, 200,
200, red)
– CIRCLE : circle top, left, radius, color
– LINE : Line x1, y1, x2, y2, color
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Vector images
• Vector image or vector graphics can be resized
without losing the integrity of the original image.
• Scaling a vector is a mathematical operation only the attributes change, the image is
unaffected
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Primitive geometric drawing objects
• Basic
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Line
Polyline
Arc
Bezier curve
• Text
– Font, weight
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• Shapes
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Circle
Ellipse
Rectangle
Square
Pie segment
Triangle
Pentagon,
hexagon,
heptagon,
octagon, etc
Text
Text
Scaling vector graphics
Shown
magnified
Original image
V e c to r
g r a p h ic s
V e c to r
g r a p h ic s
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Advantages and Disadvantages
of using vector image
• Advantages
– Relatively small amount of data required to represent
the image.
– Therefore, it does not required a lot of memory to
store
– Easier to manipulate
• Disadvantages
– Limited level of detail than can be presented in an
image
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Software to create vector
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Software to create images
• Graphics programs are tools that allow an artist to create and edit
designs used in multimedia applications.
• Generally, graphics programs can be categorized as:
– Drawing programs
• Creating draw type graphics
• Provide freehand. Example geometric shape
• Example : Adobe Illustrator, Corel Draw, Macromedia Freehand
– Paint programs
• Those creating bitmaps
• Useful in creating original art
• Example: Paint Shop Pro
– Image editing programs
• Making changes to existing images, such as manipulating the brightness or
contrast, applying textures, patterns
• Examples : Adobe Photoshop, Corel PhotoPaint
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Vector formats
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Windows metafile (.wmf)
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SVG - Scalable Vector Graphics (.svg)
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A page description language common on the web
Drawing Exchange Format (.dfx)
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A page description language used to control printers
Adobe Portable Document Format (.pdf)
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Older format commonly used for clip art
Adobe PostScript (.ps)
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A new format devised for the web
CGM - Computer Graphics Metafile (.cgm)
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Used by Microsoft Windows
Store 3D image created by design program AutoCAD
Encapsulated PostScript (.epf)
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Professional printing: Illustration program, Adobe Systems, Desktop Publishing programs
3-Dimensional Graphic models
• A 3D model is a variation on
the vector format
• The location of a 3dimensional object is specified
using x, y and z co-ordinates
X
• Further primitives can be found
in 3D models
– Cube, sphere, pyramid, etc.
– Camera, spotlight, texture,
shading etc.
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3D model
Y
Z
3-Dimensional Graphic models
• 3D graphics offer the photorealistics effects that
have you seen in TV, Computer Games
• Examples, Motion Picture films such as:
– The Incredibles, Shrek, Happy Feet, Transformer, etc.
• Examples 3D programs:
– Lightwave
– 3D Studio Max
– Maya
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Photorealistics Effects
Transformer the Movie (2007)
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Software to create 3D image
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3-Dimensional Graphic models
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Photorealistics Effects
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Hardware used to acquire images
• Scanners and digital imaging
products
• Many forms of scanner
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Drum
Flat-bed
Negative / slide
Hand-held
• Important to check the optical
resolution of the scanner
– measured in dots per inch (DPI)
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Hardware used to acquire images
• Digital camera
– Uses digital memory instead of film
– Images are transferred to computer via a
cable
– Can be very high resolution
• Stills from a camcorder or PC “webcam” type camera
– Home products tend to be low resolution
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Hardware used to create / edit images
Tablet and pen
• Graphics tablet and pen
– Preferred by digital artists
– Pressure sensitivity
• Digitiser tablet
– Preferred by technical artists
– Mouse has accurate crosshair to
help digitise drawings
Digitiser
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TrueType / PostScript Type font
Converting image formats
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Render as bitmap
Contour trace
Vector image
Text
Optical Character
Recognition (OCR)
Bitmapped image
Bitmapped font
Working With Graphics
• Considerations and guidelines when we
are working with graphics:
– Choose the graphic depend on your work
– Choose the correct software
– Use minimum color depth
– Delivery Systems
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How graphics/images can be used effectively
• Different types of graphics are used in different
ways:
– Line drawing are graphical representations of physical
objects. There are 3 kinds of line drawings:
• Isometric - represent 3-D objects without realistic perspective
• Orthographic - are 2-D representations of objects
• Perspective - represent objects in their most realistic form
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How graphics/images can be used effectively
• Graphs and Tables
– In just a glance, graphs can
provide specific data, show
general trends in data or depict
the relationships between data
and data trends
• Diagrams
– Help users conceptualize a
process, flow or
interrelationship. Examples of
diagrams include: Flow charts,
Schematic Drawings and Block
Diagrams.
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Advantages and Disadvantages of using images
• Advantages
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Convey a lot of information quickly
Add visual simulation and colour
Can communicate across language borders
Enhance other media
• Disadvantages
– Do not provide in-depth explanations
• Graphics rarely suffice to convey a whole message in
business, technical or safety settings
– Can be misinterpreted
• Graphics should be used carefully to make sure the message
is not ambiguous or cryptic
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Q&A
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