Matakuliah
Tahun
Versi
: T0553/Sistem Multimedia
: 2005
:5
Pertemuan 05
Graphics
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Menunjukkan Penggunaan Gambar pada
Aplikasi Multimedia
2
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.
• Images play an important part in multimedia
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Navigation
User interface components
Help systems
Clip art
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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
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Bitmaps Image
• A pixel is the smallest element of resolution on a
computer screen (Screen Resolution)
• A pixel is the basic unit of a digital images. Digital image
is a picture that may be stored in, displayed on,
processed by a computer.
• As mentioned, bitmap is composed of a matrix elements
called pixels
• Each pixel can be in a specific colour and each pixel
consists of two or more colors.
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Bitmaps Image
• The range of these colours is known as the
colour depth.
• The color depth determined “How much data in
bits used to determined the number of colors”.
• 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
• 1 bit per pixel = 2 colours (monochrome)
• 2 bits per pixel = 4 colours
• 4 bits per pixel = 16 colours
• 8 bits per pixel = 256 colours
– Generally good enough for colour images
• 16 bits per pixel = 65536 colours
– Better quality for photograph-like images, also known as high colour
• 24 bits per pixel = >16 million possible colours
– Used to recreate photo realistic images, also known as true colour
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Bitmaps Image
• The more colours that are allowed per pixel, the
greater the size of the image
• 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 
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• 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 

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8
 921600 bytes
 900KB
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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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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
• Shapes
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Circle
Ellipse
Rectangle
Square
Pie segment
Triangle
Pentagon,
hexagon,
heptagon,
octagon, etc
Text
Text
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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 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
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3-Dimensional Graphic models
• A 3D model is a variation on
the vector format
• The location of a 3-dimensional
object is specified using x, y
and z co-ordinates
X
• Further primitives can be found
in 3D models
3D model
– Cube, sphere, pyramid, etc.
– Camera, spotlight, texture,
shading etc.
Y
Z
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3-Dimensional Graphic models
• 3D graphics offer the photorealistics effects that
have you seen in TV, Computer Games
• Examples, Motion Picture films such as:
– Jurassic Park, Terminator 2, Lost World and Toy Story
• Examples 3D programs:
– Carigali Truespace
– 3D Studio Max
– Infini-D
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3-Dimensional Graphic models
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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
“web-cam” type camera
– Home products tend to be low
resolution
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Hardware used to create / edit
images
• Graphics tablet and pen
– Preferred by digital artists
– Pressure sensitivity
Tablet and pen
• Digitiser tablet
– Preferred by technical
artists
– Mouse has accurate
crosshair to help digitise
drawings
Digitiser
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Converting image formats
TrueType / PostScript Type font
Render as bitmap
Contour trace
Vector image
Text
Optical Character
Recognition (OCR)
Bitmapped image
Bitmapped font
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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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