4.5.6.4-6 FoDR (Representing images, sound and other data) Flashcards
How are bitmaps represented
- Made up of discrete pixels of colour
-Each pixel is mapped to and controlled by a sequence of bits in memory
What is a pixel
Picture element - the smallest addressable unit of a bitmap image
What is resolution
The number of dots per inch where a dot is a pixel.
What is meant by the size in pixels of an image
width of image in
pixels x height of image in pixels
What is meant by colour depth
The number of bits used to store each pixel
What is the inequality for colour depth
2ˣ >= n
- x –> Colour depth
- n –> number of colours
What is the equation for storage requirements
file size = size of an image x colour depth
What factor are you ignoring in the storage requirement equation
The metadata of the bitmap image
What is metadata
Data stored about the bitmap image
What are example of metadata
- Image width
- image height
- colour depth
- file size
- image size
- resolution
- type of compression used
What are the factors affecting the storage requirement of a bitmap image
- Metadata
- Resolution
- Colour Depth
How do vector graphics represent images
- Vector graphics are made of a list of objects
- The properties of each object is stored in a list
-These properties are called primitives
What are some typical primitive data about objects
-Object type
-Fill colour
-Edge colour
-Line width
-Line style
What are the advantages of vector graphics over bitmap images
For geometric images:
- less storage space likely to be needed
- Will load faster from secondary storage
- Will download faster due to lower bandwidth
Generally:
- Can be scaled without a loss of quality
- Image can be searched for individual objects
- Easy to manipulate individual objects
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