Graphics Pertemuan 4 Matakuliah: T0732 / Sistem Multimedia Tahun: 2007

Bina Nusantara Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Menunjukkan Penggunaan Gambar pada Aplikasi Multimedia

Bina Nusantara Outline Materi What is an Image Image Media Types Bitmap Image Vector Image 3-Dimensional Graphic Models Working With Graphics

Bina Nusantara 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: –Photographs –Drawings –Paintings –Television and motion pictures –Semantics –Maps, etc.

Bina Nusantara What is an Image? Images play an important part in multimedia –Navigation –User interface components –Help systems –Clip art

Bina Nusantara 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 (mathematically defined)

Bina Nusantara Raster Image A pixel is the smallest element of resolution on a computer screen (Screen Resolution) Bitmap  matrix of pixel Each pixel can be in a specific colour and each pixel consists of two or more colors. The range of these colours is known as the colour depth. 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

Bina Nusantara 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 = 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

Bina Nusantara Colour Depth True Colour (24 bits) 8 bits 4 bits1 bit

Bina Nusantara Raster Image More colour per pixel  bigger image size 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

Bina Nusantara Bitmaps images Original image Shownmagnified

Bina Nusantara 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)

Bina Nusantara Example A 640 x 480 pixel image in 24-bit colour would require how much disk space?

Bina Nusantara Type of Compression Lossless compression : Modify the way the data is organized or represented to reduce storage size. No loss in detail; Example: ‘Run-length Encoding’. Original : AAABBBCCCCCCABCABC RLE : 3A3B6C2ABC

Bina Nusantara Type of Compression Lossy compression schemes: Try to maximise compression without loss obvious to human user. Remove detail during the compression NOTE: repeated compression caused loss in quality

Bina Nusantara

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

Bina Nusantara 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

Bina Nusantara Software to create bitmap images Popular PC packages include: –Microsoft Paint Included with microsoft windows –Microsoft PhotoDraw –Adobe Photoshop –Paint Shop Pro –Macromedia Fireworks

Bina Nusantara Software to create raster

Bina Nusantara 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.

Bina Nusantara 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

Bina Nusantara 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

Bina Nusantara 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

Bina Nusantara Scaling vector graphics Original image Shownmagnified

Bina Nusantara 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

Bina Nusantara Software to create vector

Bina Nusantara 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

Bina Nusantara 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

Bina Nusantara 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. 3D model X Y Z

Bina Nusantara 3-Dimensional Graphic models 3D graphics offer the photorealistics effects that have you seen in TV, Computer Games Examples, Motion Picture films such as: –The Incredibles, Shrek, Happy Feet, Transformer, etc. Examples 3D programs: –Lightwave –3D Studio Max –Maya

Bina Nusantara Photorealistics Effects Transformer the Movie (2007)

Bina Nusantara Software to create 3D image

Bina Nusantara 3-Dimensional Graphic models

Bina Nusantara Photorealistics Effects

Bina Nusantara 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)

Bina Nusantara 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

Bina Nusantara 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

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

Bina Nusantara 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

Bina Nusantara 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

Bina Nusantara 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.

Bina Nusantara Advantages and Disadvantages of using images Advantages –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

Bina Nusantara Q & A