topic 2 - Fundamentals of data representation

• A compression technique used to reduce the number of bits used to represent each letter

  Huffman coding
• A simple form of lossless compression in which runs of data are stored using frequency/data pairs

  Run length encoding
• A data encoding method where files are compressed but no data is lost

  Lossless compression
• A data encoding method where files are compressed by removing some of the detail

  Lossy compression
• The frequency with which you record the amplitude of the sound

  Sample rate
• The number of bits used to store each sample

  Sample resolution
• A measure of amplitude at a point in time

  A Sample
• (image width x image height x colour depth) / 8

  File size in bytes
• image width x image x colour depth


  File size in bits
• The number of bits per pixel


  Colour depth
• Unicode represents the characters of all the languages of the world. Unicode uses between 8,16 or 32 bits per character. It uses the same codes as ASCII up to 127.


  Unicode
• The basic ASCII codes use 7 bits for each character. This gives a total of 128 possible unique symbols. The extended ASCII code uses 8 bits, which gives an additional 128 character (256 in total).


  ASCII code
• Divides the number by two for every right shift

  Right binary shift
• Multiplies the number by two for every left shift

  Left binary shift
• The smallest addressable unit of memory in a computer

  A byte