Data Representation Flashcards
What is a character set?
A defined list of characters recognised by a unique binary number.
Give some examples of character sets
ASCII, Unicode
What does ASCII stand for?
American standard for information interchange
What makes Unicode special?
It is international
What are the two ways images can be stored?
Bitmaps , vectors
What are bitmaps made up of?
Coloured squares
How are vectors made?
They store the mathematics to draw coloured shapes
What does the number of bits required for pixel depend on?
The number of colours required
How can the number of coloured be calculated?
2^n
What is the number of bits used for each pixel known as?
Colour depth
What is metadata?
Additional data stored within the image
Examples of metadata are…
Image width, height , colour depth, colour palette
Does the file size decrease or increase when the colour depth and resolution are increased?
Increase
What do bitmaps usually store?
Pictures
What do vectors usually store?
Technical drawings, logos, clip art
What is the sound file size?
The total number of bits in a sound
How is the sound file size found?
Number of samples per second X number of bits per sample X length of sample in seconds
What is the boy depth?
The number of bits stored per sample
The higher the number of bits … the greater/worse the quality of sound?
Greater
What is sample rate?
The number of samples stored per second
What is compression?
Reducing the number of bits in a file
Why is compression used?
To make the storage capacity of a file lower, making transfer of the file quicker
What are the differences of lossy and lossless compression?
LOSSY:
-some of the data is lost and cannot be recovered
-Greatly reduces file size
-Reduces the quality of the image/sound
LOSSLESS:
-None of the data is lost, it is encoded differently
-Can be turned back into the original format
-Less effective than Lossy
What type of files can Lossy work on?
Images, sound, video
