raster = made from a grid of pixels, squares of colour made in a grid
raster = 1 colour value for each pixel in the image
vector = made from shapes with a built in maths formula for positioning these shapes
pixels = (pic)ture (el)ements, smallest possible unit of image data
file format = a standard way that a file to be made up by a computer program
file format = an expected file structure made by an application so that the application can open it again eg Microsoft Word .doc or docx
file format = how the information inside the file is organised
file format = examples are below... they are identified by the file extension .pdf or .mp3 etc
Raster Images - BMP
bmp is file format by microsoft as a device independent bitmap (DIB) and usually saved as .bmp
have a fixed resolution
edited in paint programs
no animation
no transparency
uncompressed
large file size
resolution dependent
require large memory to store because it stores every pixel
perfect for photographs with lots of colours
used for print, not the web
measured in dots per inch, and/or pixel dimensions
Raster Images - GIF
is a compressed image format, uses lossless LZW compression
animated gifs very popular on the www, even without a plugin
most suitable for flat colour
transparency = yes
use 8-bit colour, maximum 256 colours
1 colour can be used to designate transparency
Common format for text, clip art, animation, icons, logos, simple diagrams, line drawings graphics with large blocks of single colour, graphics with transparent areas
Raster Images - JPEG, JPG,
is a lossy compressed image format
24-bit colour, 16.7 million colours
no transparency
no animation
adjustable compression
ideal for colour photos
Common format for photographs, emailing photos, digital cameras
Raster Images - TIF
no animation
no transparency
compressed (lossy and lossless) or uncompressed
compressed is recommended
24 bit, 16 million colours
Common format for raw bitmap data, high resolution printing, not good for internet as too long to download - too big in file size
Raster Images - PNG
can use 8-bit or 24-bit colour, 16 million colours
lossless compression
no animation
yes transparency
only web image format to support alpha channels
higher quality substitute for GIF, more effective compression
not good for photos, good for web when compressed
common format for online viewing of images
some older browsers need a plugin for it to work
Vector Images
Based on coordinates X (horizontal) and y (vertical)
Made up of mathematical equations
created from mathematical formulas used to define lines, shapes and curves
can be scaled to any size
don’t have a background
resolution independent (change size and still high quality)
shapes can be edited by moving drawing points
anti-aliasing softens ‘jaggies’
must be rendered for display
rendered before filters and effects
require little memory to store because it stores only the maths calculation and essentials
perfect for logos, cartoons, clipart and illustrating with few colours
good for fonts and text effects
poor colour quality = not good for photos
can be downloaded quickly because small file size
created by vector applications like Adobe Illustrator and Corel Draw
.wmf (Windows Meta File, can be vector or raster)
.dwg (dwg from drawing, CAD packages)
.eps (Encapsulated PostScript, used in Adobe Illustrator)
.pdf (Portable Document Format, first with Adobe Reader)
.ai (Adobe Illustrator)
.svg (Scalable Vector Graphics)
Vector Image .cgm
stands for Computer Graphics Metafile
is a standard for 2D vector graphics and raster graphics and text
not common on the web
common in some technical applications
Vector Image .svg
stands for scalable vector graphic
svg is a standard that defines graphics in XML format (an XML document can be defined as a string of characters)
can be created and edited with text editors
can be scaled many times without losing quality
can be printed at high resolution without losing quality
Answer the following questions
What is a pixel?
What is resolution
Which image type is mathematically defined?
What is another name for a bitmap image?
Name a compressed file format?
What is a limitation of gif files?
common file formats for audio 11 ATAR, 12 GEN
audio = music, speech or any other sound
mp3 = Moving Pictures experts group MPEG-2 Layer 3 audio (mp3)
wav = Waveform audio file format
wma = Windows media audio file
codec = software/program to compress and decompress data, usually audio and video
player = special software/program to play audio files on a computer
Audio file - .mp3
mp3 is is a type of encoding
mp3 the most common audio file format on the internet
small file size, but good quality
file size can be reduced 10 times, but audio still fine = 1Mb per minute
it removes inaudible audio
Audio file - .wav
microsoft audio format for uncompressed audio
is uncompressed audio using LPCM, or linear pulse code modulation
LPCM is found in making audio CDs
file size is about 10Mb per minute
Audio file - .wma
is a sound file compressed by Windows media audio codec
designed to send audio files over the internet
less support than MP3
could be better for Windows users
Answer the questions below and save with your course notes.
Use a sound editor to make one audio file. Save or export to different sound file types and compare file sizes and quality.
Name each export version as follows; myAudioAAC256kbs.aac, m audioAAC192kbs.aac, myAudioMP364kbs.mp3 modify your actual file name to the export type
If you are using Garage Band ver 10, you will need to choose Export to Disk.
Save all your audio files to your audio files folder :)
What is the most common audio file for internet use?
What is the audio file made by Windows?
Why does MP3 have such a small file size?
Explain mp3 audio files.
Expain wav audio files.
Explain wma audio files.