Transcript Pengolahan Citra

Pengolahan Citra
Sistem Pengolahan Citra Digital
Sistem Pengolahan Citra Digital
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Merupakan suatu kesatuan yang saling
berhubungan atau terintegrasi untuk
membentuk suatu sistem antara data,
perangkat keras, perangkat lunak,
prosedure pengolahan, dan tenaga
pelaksana dalam ekplorasi citra digital
Konsep Dasar
Pengolahan citra digital merupakan manipulasi dan
interprestasi digital dari citra dengan bantuan
komputer. Konsep dasar pengolahan citra dengan data
masukan pokok (internal data) berupa langkah berikut
:
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1.
2.
3.
4.
5.
6.
7.
Pengumpulan data yang relevan, yaitu citra digital
Klasifikasi atau pengelompokan dengan cara pengkelasan
Penyusunan data sesuai kelas
Perhitungan dan manipulasi
Pengujian ketelitian dan perhitungan
Penyimpulan dan rekapitulasi hasil
Informasi
Software
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2.
Aplikasi Grafik
Pengolahan Citra Design
1.
2.
3.
3.
Rancangan Arsitektur
Rancangan Design
Animasi
Pengolahan Citra
1.
2.
3.
4.
5.
Pengolah Citra
Pembuatan Efek
Contras
Brightness
Emboss
Hardware
Perangkat Input
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Scanner
Digital Camera
Perangkat Output
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Printer
Plotter
Monitor
Aspek penentuan kualitas citra dari perangkat keras :
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Resolusi
Warna
Kecepatan
Kapasitas
Proses Pengolahan Data Citra
Secara Umum
Citra
ADC
Citra Digital
Proses
Kompresi
Media Penyimpan
Proses
Dekompresi
Citra Digital
Pengkodean Bit
ke Tabel Warna
Layar
Perangkat Input Data
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Perangkat input data yang digunakan
diantaranya perangkat penangkap atau capture
citra yang bekerja membaca citra dengan cara
dijelajahi dan kemudian dilakukan proses
konfersi kedalam data digital.
Perangkat capture ini memiliki 3 (tiga) elemen
dasar :
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Sensor intensitas cahaya
Penjelajah untuk merekam seluruh bagian citra
Analog Digital Converter (ADC)
Perangkat Output data
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Diantara perangkat keras output diantaranya layar
menggunakan perangkat pengolah data yang dikenal
sebagai Card VGA atau Display Processor dengan cara
kerja seperti terlihat dalam gambar berikut :
Display ProcessorCPUMemoryDisplay Processor
Layar
CPU
I/O
Display
Processor
Layar
Memory
Display Processor akan mengubah digital ke analog,
digunakan untuk berinteraksi dengan CPU dan
mengontrol operasi dari display device
Mode Layar Monitor
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Mode Teks :
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Mode Grafiks (Resolusi)
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25 x 80
25 x 40
320 x 200
640 x 200
640 x 400
800 x 600
640 x 480
1024 x 768
1180 x 1024
1600 x 1400
Dibedakan oleh adanya Pixel  Resolusi Layar Monitor
Resolusi adalah jumlah penembakan titik pada horizontal atau
vertical tiap pixel oleh elektron gun. Resolusi merupakan jumlah
pixel percentimer vertical dan horizontal.
Monitor
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Tipe Resolusi
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Tipe Monitor
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High : Penampungan jumlah pixel pada layar maksimum
Midle
Low
Monocrome
CGA (Color Graphic Adapter)
EGA (Enchanded Graphic Adapter)
VGA (Video Graphic Array)
SVGA (Super VGA)
XGA (eXtra Graphic Array)
Warna yang dihasilkan pada setiap monitor selain tergantung pada jenis
monitor juga tergantung dari interface yang berupa Card Monitor seperti
VGA Card.
Layar dari ukuran monitor terbatas dan tidak akan tampak jelas dilihat dari
jarak jauh, untuk keperluan tersebut digunakan Computer Display Projektor.
Sistem Monitor
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Aspek Ratio (Y/X)
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Perbandingan antara Y dan X yang digunakan untuk
mendapatkan panjang yang sama antara garis vertical-horizontal
yang dibutuhkan yaitu vertical 3 pixel dan horizontal 4 pixel.
Random Scan Monitor
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Pengaksesan setiap titik secara langsung yang digunakan untuk
menelusuri titik pada tiap screen dengan cukup[ diwakili oleh 1
pixel
Raster Scan Monitor
Penggambaran suatu gambar yang sama dengan penelusuran
setiap garis
Refresh rate : 30 – 60 frames/sec
Frame = banyak pixel pada layar
Interlaced System : Teknik untuk mengatasi layar bergoyang,
dengan cara menampilkan tiap frame secara bergantian.
Jumlah Warna
2
1
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4
2
16
4
256
8
64K
16,7 M
High Color
True Color
16
24
……
Warna
….
Bit
Setiap Pixel dapat menampilakan 1 warna
Total warna yang dapat ditampilkan dapat ditentukan, sebagai
contoh
Monitor resolusi 800 x 600 warna yang ditampilkan 16,7 Juta warna,
memori yang dibutuhkan  16,7 Juta = 24 Bit
Jumlah Pixel = 800 x 600 = 480.000
1 Pixel  24 Bit = 3 Byte
480.000 x 3 / 1024 = 1440 Kb = 1,44 Mb
Image Media Types
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Images can be generally divided into two
formats:
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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
Bitmaps Image
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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.
Bitmaps Image
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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
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Remember: a bit (binary digit) is either 1 or 0 and
that there are eight bits in a byte
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
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16 bits per pixel = 65536 colours
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Generally good enough for colour images
Better quality for photograph-like images, also known as high colour
24 bits per pixel = >16 million possible colours
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Used to recreate photo realistic images, also known as true colour
Bitmaps Image
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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:
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Resolution
Color Depth
Bitmaps images
Original image
Shown
magnified
Calculating the size
of a raster image
width  height  colour depth
size in bytes 
8
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Where:
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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:
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1024 bytes = 1 kilobyte (KB)
1024 kilobytes = 1 megabyte (MB)
Example
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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
8
 921600bytes
 900KB
Popular bitmap formats
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Microsoft bitmap (.bmp)
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TIFF - Tagged Image File Format (.tif)
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Used a lot on web sites
PNG - Portable Network Graphics (.png)
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Useful for storing photographic images
GIF - Graphics Interchange Format (.gif)
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Used for faxing images (amongst other things)
JPEG - Joint Photographic Expert Group (.jpg)
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Used in microsoft windows
A new format for web graphics
PCD – Kodak photo CD
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A new format for store image in a compressed form on a CD
Advantages and Disadvantages
of using bitmap images
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Advantages
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Convey detail of information quickly
Real life
Disadvantages
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Depend on a Resolution
Effect to the image quality
Size file is big
Software to create bitmap
images
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Popular PC packages include:
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Microsoft Paint
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Microsoft PhotoDraw 2000
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http://www.adobe.com/products/photoshop/main.html
Paint Shop Pro
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http://www.microsoft.com/office/photodraw/
Adobe Photoshop
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Included with microsoft windows
http://www.jasc.com/psp6.html
Macromedia Fireworks
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http://www.macromedia.com/software/fireworks/productinfo
/
Vector images
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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
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e.g. square, line, ellipse, arc, etc.
The image consists of a set of commands
(mathematical equations) that are drawn the
object when needed.
Vector images
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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
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e.g. x-y location, fill colour, line colour, line style, etc.
Example:
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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
Vector images
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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
Primitive geometric drawing objects
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Basic
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Line
Polyline
Arc
Bezier
curve
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Shapes
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Text
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Font,
weight
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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
Advantages and Disadvantages
of using vector image
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Advantages
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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
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Limited level of detail than can be presented
in an image
Software to create images
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Graphics programs are tools that allow an artist to create
and edit designs used in multimedia applications.
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Generally, graphics programs can be categorized as:
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Drawing programs
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Paint programs
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Creating draw type graphics
Provide freehand. Example geometric shape
Example : Adobe Illustrator, Corel Draw, Macromedia Freehand
Those creating bitmaps
Useful in creating original art
Example: Paint Shop Pro
Image editing programs
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Making changes to existing images, such as manipulating the
brightness or contrast, applying textures, patterns
Examples : Adobe Photoshop, Corel PhotoPaint
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
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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
3D model
Further primitives can be found
in 3D models
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Cube, sphere, pyramid, etc.
Camera, spotlight, texture,
shading etc.
Y
Z
3-Dimensional Graphic models
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3D graphics offer the photorealistics effects that
have you seen in TV, Computer Games
Examples, Motion Picture films such as:
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Jurassic Park, Terminator 2, Lost World and Toy Story
Examples 3D programs:
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Carigali Truespace
3D Studio Max
Infini-D
3-Dimensional Graphic models
Hardware used to acquire images
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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
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measured in dots per inch (DPI)
Hardware used to acquire images
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Digital camera
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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
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Home products tend to be low
resolution
Hardware used to create / edit
images
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Graphics tablet and pen
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Tablet and pen
Preferred by digital artists
Pressure sensitivity
Digitiser tablet
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Preferred by technical
artists
Mouse has accurate
crosshair to help digitise
drawings
Digitiser
Converting
image
formats
TrueType / PostScript
Type font
Render as bitmap
Contour trace
Vector image
Text
Optical Character
Recognition (OCR)
Bitmapped image
Bitmapped font