Slide1 : LECTURE 5 THE USES OF IMAGES IN MULTIMEDIA
Prepared by
Cik Nor Anita Fairos bt Ismail
Objective : Objective What is an image?
The types of image
Bitmap
Vector
3D models
Hardware used to acquire / edit images
Converting from one format to another
What is an image? : 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.
What is an image? : Images show us the prominent features of the objects that they represent.
These images are composed quite differently, each is an effective
representation of its subject What is an image?
What is an image? : What is an image? Images play an important part in multimedia
Navigation
User interface components
Help systems
Clip art
Image media types : Image media types Images can be generally divided into two formats:
Bitmapped or raster images
Vector graphics or Metafile images
Bitmapped images are stored as an array of pixels
Vector graphics are stored as the set of graphic primitives required to represent the image
Bitmaps Image : 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.
Bitmaps Image : 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
Colour depth : 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
Bitmaps Image : 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
Bitmapped images : Bitmapped images Original image Shown
magnified
Calculating the size of a raster image : 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)
Example : Example A 640 x 480 pixel image in 24-bit colour would require how much disk space?
Popular bitmap formats : 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
Popular bitmap formats : Popular bitmap formats 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
Advantages and Disadvantages of using bitmap images : 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
Software to create bitmap images : 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/
Vector images : 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.
Vector images : 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)
Vector images : Vector images CIRCLE : circle top, left, radius, color
LINE : Line x1, y1, x2, y2, color
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 Q: Could you defined what the different between a digital image
and Computer Graphics or graphics?
Primitive geometric drawing objects : Primitive geometric drawing objects Basic
Line
Polyline
Arc
Bezier curve
Text
Font, weight
Shapes
Circle
Ellipse
Rectangle
Square
Pie segment
Triangle
Pentagon, hexagon, heptagon, octagon, etc
Scaling vector graphics : Scaling vector graphics
Advantages and Disadvantages of using vector image : 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
Software to create vector images : Software to create vector 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
http://www.adobe.com/products/illustrator/main.html
Software to create vector images : Software to create vector images Paint programs
- Those creating bitmaps
useful in creating original art
Example: Paint Shop Pro
http://www.jasc.com/psp6.html
Image editing programs
Making changes to existing images, such as manipulating the brightness or contrast, applying textures, patterns.
Examples : Adobe Photoshop, Adobe Page Maker,
Vector formats : 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
Vector formats : Vector formats 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
3-Dimensional Graphic models : 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
3-Dimensional Graphic models : 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
3-Dimensional Graphic models : 3-Dimensional Graphic models
3-Dimensional Graphic models : 3-Dimensional Graphic models
Hardware used to acquire images : 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) Slide scanner Flatbed scanner
Hardware used to acquire images : 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 Web cam Digital camera
Hardware used to create / edit images : 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
Converting image formats : Converting image formats Bitmapped font TrueType / PostScript Type 1 font Optical Character
Recognition (OCR) Contour trace Render as bitmap
Working With Graphics : 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
How graphics/images can be used effectively : 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
How graphics/images can be used effectively : 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.
Advantages and Disadvantages of using images : 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
Advantages and Disadvantages of using texts : Advantages and Disadvantages of using texts 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.
Summary : Summary Today we have met the various types of image that are useful when creating multimedia applications
Pros and cons of bitmapped and vector images
What hardware is used to create each of these
Next lecture... : Next lecture... We will look at digital Audio formats