pengolahan citra iii sistem pengolahan citra digital

7/22/2019 Pengolahan Citra III Sistem Pengolahan Citra Digital

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Pengolahan CitraSistem Pengolahan Citra Digital


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Sistem Pengolahan Citra Digital

Merupakan suatu kesatuan yang salingberhubungan atau terintegrasi untukmembentuk suatu sistem antara data,

perangkat keras, perangkat lunak,prosedure pengolahan, dan tenagapelaksana dalam ekplorasi citra digital


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Konsep Dasar

Pengolahan citra digital merupakan manipulasi daninterprestasi digital dari citra dengan bantuankomputer. Konsep dasar pengolahan citra dengan datamasukan pokok (internal data) berupa langkah berikut

:1. Pengumpulan data yang relevan, yaitu citra digital

2. Klasifikasi atau pengelompokan dengan cara pengkelasan

3. Penyusunan data sesuai kelas

4. Perhitungan dan manipulasi

5. Pengujian ketelitian dan perhitungan6. Penyimpulan dan rekapitulasi hasil

7. Informasi


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Software

1. Aplikasi Grafik2. Pengolahan Citra Design

1. Rancangan Arsitektur2. Rancangan Design3. Animasi

3. Pengolahan Citra1. Pengolah Citra2. Pembuatan Efek3. Contras4. Brightness5. 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 UmumCitra ADC Citra Digital

ProsesKompresi

Media Penyimpan

ProsesDekompresi

Citra Digital Pengkodean Bitke Tabel Warna

Layar


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Perangkat Input Data

Perangkat input data yang digunakandiantaranya perangkat penangkap atau capturecitra yang bekerja membaca citra dengan cara

dijelajahi dan kemudian dilakukan proseskonfersi kedalam data digital.

Perangkat capture ini memiliki 3 (tiga) elemendasar :

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 layarmenggunakan perangkat pengolah data yang dikenalsebagai Card VGA atau Display Processor dengan carakerja seperti terlihat dalam gambar berikut :

Display ProcessorCPUMemoryDisplay Processor Layar

I/O

Display Processor akan mengubah digital ke analog,digunakan untuk berinteraksi dengan CPU danmengontrol operasi dari display device

CPU

Memory

DisplayProcessor

Layar


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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 jumlahpixel 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 jenismonitor juga tergantung dari interface yang berupa Card Monitor sepertiVGA Card.

Layar dari ukuran monitor terbatas dan tidak akan tampak jelas dilihat darijarak jauh, untuk keperluan tersebut digunakan Computer DisplayProjektor.


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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-horizontalyang 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 1pixel

Raster Scan Monitor Penggambaran suatu gambar yang sama dengan penelusuran

setiap garis Refresh rate : 3060 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

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 = 480.0001 Pixel 24 Bit = 3 Byte

480.000 x 3 / 1024 = 1440 Kb = 1,44 Mb

2 4 16 256 64K 16,7 M Warna

High Color True Color

1 2 4 8 16 24 . Bit


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Image Media Types

Images can be generally divided into twoformats: Bitmapped or Raster images

Draw-type or Vector graphics or Metafile images

Bitmapped images are stored as an array ofpixels. It represents the image as an array of

dots, called pixels

Vector graphics are stored as geometric shapeto represent the image


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Bitmaps Image

A pixel is the smallest element of resolution on acomputer screen (Screen Resolution)

A pixel is the basic unit of a digital images. Digital imageis a picture that may be stored in, displayed on,processed by a computer.

As mentioned, bitmap is composed of a matrix elementscalled 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 thecolour depth.

The color depth determined How much data inbits 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



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

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, thegreater the size of the image

The number of pixels is related to the size of filethat 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

Shownmagnified


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8bytesinsize depthcolourheightwidth

Calculating the size

of 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 wouldrequire how much disk space?

900KB

bytes921600

87372800

824480640bytesinsize


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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

PCDKodak 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 graphicprimitives required to represent the image

A graphic primitive is a simple graphic based ondrawing 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 theobject when needed.


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Vector images

Storing and representing images by mathematicalequations is called vector graphics or Object Orientedgraphics.

Each primitive object has various attributes that go tomake 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 resizedwithout losing the integrity of the original image.

Scaling a vector is a mathematical operation -only the attributes change, the image isunaffected


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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

TextText


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Scaling vector graphics

Original image

V e c t o r

g r a p h i c s

Shownmagnified

V e c t o r

g r a p h i c 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 ofmemory 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 createand 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) Professional printing: Illustration program, Adobe Systems, Desktop Publishing programs


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3-Dimensional Graphic models

A 3D model is a variation onthe vector format

The location of a 3-dimensionalobject is specified using x, yand z co-ordinates

Further primitives can be foundin 3D models

Cube, sphere, pyramid, etc.

Camera, spotlight, texture,shading etc.

3D model

X

Y

Z


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3D graphics offer the photorealistics effects thathave 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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Hardware used to acquire images

Scanners and digital imagingproducts

Many forms of scanner

Drum

Flat-bed

Negative / slide

Hand-held

Important to check the opticalresolution of the scanner

measured in dots per inch (DPI)


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Hardware used to acquire images

Digital camera

Uses digital memory instead offilm

Images are transferred tocomputer via a cable

Can be very high resolution

Stills from a camcorder or PCweb-cam type camera

Home products tend to be lowresolution


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Hardware used to create / edit

images

Graphics tablet and pen

Preferred by digital artists

Pressure sensitivity

Digitiser tablet

Preferred by technicalartists

Mouse has accuratecrosshair to help digitisedrawings

Tablet and pen

Digitiser


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Converting image formats

Text

Bitm

apped

image

V

ectorim

age

Bitmapped font

TrueType / PostScript Type font

Optical CharacterRecognition (OCR)

Contour trace

Render as bitmap

pengolahan citra iii sistem pengolahan citra digital

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