Pengolahan Citra

1. Pengolahan Citra Sistem Pengolahan Citra Digital

2. 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

3. 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

4. Software • Aplikasi Grafik • Pengolahan Citra Design • Rancangan Arsitektur • Rancangan Design • Animasi • Pengolahan Citra • Pengolah Citra • Pembuatan Efek • Contras • Brightness • Emboss

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

6. Proses Kompresi ADC Citra Citra Digital Media Penyimpan Proses Dekompresi Pengkodean Bit ke Tabel Warna Citra Digital Layar Proses Pengolahan Data Citra Secara Umum

7. 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)

8. CPU Layar Display Processor Memory 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

9. 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.

10. 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.

11. 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.

12. 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 = 480.000 1 Pixel  24 Bit = 3 Byte 480.000 x 3 / 1024 = 1440 Kb = 1,44 Mb

13. 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

14. 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.

15. 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

16. 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

17. 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

18. Bitmaps images Original image Shown magnified

19. 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)

20. Example • A 640 x 480 pixel image in 24-bit colour would require how much disk space?

21. 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

22. 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

23. 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/

24. 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.

25. 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

26. 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

27. Shapes Circle Ellipse Rectangle Square Pie segment Triangle Pentagon, hexagon, heptagon, octagon, etc Basic Line Polyline Arc Bezier curve Text Font, weight Primitive geometric drawing objects

28. Shown magnified Original image Scaling vector graphics

29. 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

30. 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

31. 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

32. 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

33. 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

34. 3-Dimensional Graphic models

35. 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)

36. 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

37. 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

38. Converting image formats TrueType / PostScript Type font Bitmapped font Render as bitmap Text Bitmapped image Vector image Contour trace Optical Character Recognition (OCR)