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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.
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- What do graphics look like?
Graphics can be:
Black and White
Grayscale
Color
Still
Animated
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- 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.
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- 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
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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
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- 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.
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- 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
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- Bitmapped images
Original image
Shown
Magnified
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- 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)
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- 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
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- 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
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- Software to create bitmap images
Popular PC packages include:
Microsoft Paint
Microsoft PhotoDraw 2000
Adobe Photoshop
Paint Shop Pro
Macromedia Fireworks
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- 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.
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