Lecture Chapter 3: Graphics

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Lecture "Chapter 3: Graphics" presentation of content: What is a graphics, what is an image, introduction about adobe photoshop software, creating graphics by adobe photoshop, modifying graphics, modifying graphics, creating special effects, design website interface.

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Nội dung Text: Lecture Chapter 3: Graphics

Graphics 1
Objective  What is a Graphics  What is an Image  Introduction about Adobe Photoshop Software  Creating Graphics by Adobe Photoshop  Modifying Graphics  Adding Text to Graphics  Creating Special Effects  Design WebSite interface 2
What is a Graphics?  Graphics are building blocks for developing exciting and informative multimedia documents, presentations, and publications.  They are the images you use to enhance the work you do on your computer, and include drawings, paintings, logo, Navigation button, diagram, photographs, cartoons, charts, and maps.  Graphics programs provide the tools you need to create, edit, and mainpulate images on your computer. 3
What do graphics look like?  Graphics can be:  Black and White  Grayscale  Color  Still  Animated 4
What do graphics do?  Graphics can:  Illustrate or demonstrate procedures  Clarify data  Convey ideas  Tell stories  Add visual appeal 5
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. 6
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 7 representation of its subject
What is an image?  Images play an important part in multimedia  Navigation  User interface components  Help systems  Clip art 8
Image media types Images can be generally divided into two formats:  Bitmapped or raster images  Bitmapped graphics, also known as raster graphics, consist of grids of tiny dots called pixels. Each pixel is assigned a color.  Bitmapped images are stored as an array of pixels  Vector graphics or Metafile images  Vector graphics use mathematical formulas to define lines, curves, and other attributes.  Vector graphics are stored as the set of graphic primitives required to represent the image 9
Bitmaps Image  A pixel is the smallest element of resolution on a computer screen (Screen Resolution). Each pixel can be in a specific colour and each pixel consists of two or more colors.  A bitmap is composed of a matrix elements called pixels  Color depth refers to the number of distinct colors an image can contain. It can range from 2-bit (black and white) to 24- bit (16.7 million colors). Colour depth is measured in bits per pixel.  Resolution is the number of pixels per inch. 10
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(hiện thực), also known as true colour 11
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.  Two factors effect the size file bitmap are:  Resolution  Color Depth 12
Bitmapped images Original image Shown Magnified 13
Calculating the size of a raster image width height colour depth size in bytes 8  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) 14
Example  A 640 x 480 pixel image in 24-bit colour would require how much disk space? 640 480 24 7372800 size in bytes 8 8 921600 bytes 900KB 15
Popular bitmap formats  Microsoft bitmap (.bmp)  Used in microsoft windows  Supports pixel resolution up to 24 bits  TIFF - Tagged Image File Format (.tif)  Used for faxing images  Supports pixel resolution up to 48 bits  JPEG - Joint Photographic Expert Group (.jpg)  Useful for storing photographic images 16
Popular bitmap formats  GIF - Graphics Interchange Format (.gif)  Index(8 bits) of 24 bits(8R+8G+8B) is sent  Used a lot on web sites  PNG - Portable Network Graphics (.png)  BMP image format with lossless data compression. PNG was created to improve upon and replace the GIF format  A new format for web graphics  PCD – Kodak Photo CD  A new format for store image in a compressed form on a CD 17
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 18
Software to create bitmap images  Popular PC packages include:  Microsoft Paint  Microsoft PhotoDraw 2000  Adobe Photoshop  Paint Shop Pro  Macromedia Fireworks 19
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. 20