Pengolahan Citra

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Pengolahan Citra

• Sistem Pengolahan Citra Digital

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Sistem Pengolahan Citra Digital

• 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

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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
• 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

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Software

1. Aplikasi Grafik
2. Pengolahan Citra Design
3. Rancangan Arsitektur
4. Rancangan Design
5. Animasi
6. Pengolahan Citra
7. Pengolah Citra
8. Pembuatan Efek
9. Contras
10. Brightness
11. Emboss

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Hardware

• Perangkat Input
• Scanner
• Digital Camera
• Perangkat Output
• Printer
• Plotter
• Monitor
• Aspek penentuan kualitas citra dari perangkat
  keras
• Resolusi
• Warna
• Kecepatan
• Kapasitas

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Proses Pengolahan Data Citra Secara Umum
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Perangkat Input Data

• 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
• Sensor intensitas cahaya
• Penjelajah untuk merekam seluruh bagian citra
• Analog Digital Converter (ADC)

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Perangkat Output data

• 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
• I/O
• Display Processor akan mengubah digital ke
  analog, digunakan untuk berinteraksi dengan CPU
  dan mengontrol operasi dari display device

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Mode Layar Monitor

• Mode Teks
• 25 x 80
• 25 x 40
• Mode Grafiks (Resolusi)
• 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.

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Monitor

• Tipe Resolusi
• High Penampungan jumlah pixel pada layar
  maksimum
• Midle
• Low
• Tipe Monitor
• 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.

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Sistem Monitor

• Aspek Ratio (Y/X)
• 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
• 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.

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Jumlah Warna
2 4 16 256 64K 16,7 M Warna
High Color True Color
1 2 4 8 16 24 . 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

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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 gt16 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 sizeof a raster image

• 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?

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Popular bitmap formats

• Microsoft bitmap (.bmp)
• Used in microsoft windows
• TIFF - Tagged Image File Format (.tif)
• Used for faxing images (amongst other things)
• JPEG - Joint Photographic Expert Group (.jpg)
• Useful for storing photographic images
• GIF - Graphics Interchange Format (.gif)
• Used a lot on web sites
• PNG - Portable Network Graphics (.png)
• A new format for web graphics
• 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/produ
  ctinfo/

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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

• Shapes
• Circle
• Ellipse
• Rectangle
• Square
• Pie segment
• Triangle
• Pentagon, hexagon, heptagon, octagon, etc

• Basic
• Line
• Polyline
• Arc
• Bezier curve
• Text
• Font, weight

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Scaling vector graphics
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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

• Windows metafile (.wmf)
• Used by Microsoft Windows
• SVG - Scalable Vector Graphics (.svg)
• A new format devised for the web
• CGM - Computer Graphics Metafile (.cgm)
• Older format commonly used for clip art
• Adobe PostScript (.ps)
• A page description language used to control
  printers
• Adobe Portable Document Format (.pdf)
• A page description language common on the web
• Drawing Exchange Format (.dfx)
• Store 3D image created by design program AutoCAD
• Encapsulated PostScript (.epf)

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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
• Further primitives can be found in 3D models
• Cube, sphere, pyramid, etc.
• Camera, spotlight, texture, shading etc.

X
3D model
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
• 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
• Digitiser tablet
• Preferred by technical artists
• Mouse has accurate crosshair to help digitise
  drawings

Tablet and pen
Digitiser
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Converting image formats
TrueType / PostScript Type font
Bitmapped font
Render as bitmap
Text
Bitmapped image
Vector image
Contour trace
Optical Character Recognition (OCR)