Characters

• Binary can be used to represent..?

  characters
• Define what a characters set is.

  Collections of characters that a computer recognises from their binary representation.
• Name two character sets.

  ASCII

  Unicode
• Each character in ASCII is given how big of a binary code?

  7 bit
• How many characters can ASCII represent?

  128
• Each ASCII character fits nicely into 1 byte because?

  a 0 is added to the front of every 7 bit binary, making 8
• Unicode uses multiple what for each character?

  bytes
• Unicode cover all major what?

  languages
• How do you work out the file size of a text file?

  file size in bits=number of bits per character x number of characters
• How are images stored?

  As a series of pixels
• What are images called when they are made up of pixels?

  bitmap images
• Each colour in an image is represented by what?

  a binary code
• What does increasing colour depth increase?

  file size
• What is colour depth?

  The number of bits used for each pixel
• How can you work out how many colours can be made when you have colour depth?

  total number of colours= 2^n (n is number of bits per pixel)
• Image resolution=?

  number of pixels in image
• Give formula for calculating file size of an image in bits

  image resolution x colour depth = width x height x colour depth
• What is metadata needed for?

  to display images
• What is metadata?


  The information stored in an image which helps the computer recreate the image
• Give metadata examples for an image

  width

  height

  file format

  colour depth

  resolution
• Sound is sampled and stored digitally
• Sound is recorded by a microphone as an analogue signal
• Analogue signals are pieces of continually changing data
• Analogue needs to be converted into digital data so that computers can read and store sound files.
• The process of converting analogue to digital is called sampling.
• How do you convert analogue to digital?

  Sample amplitude of wave at regular intervals

  The amplitude can only take certain values depending on the bit depth
• What affects size and quality of sound files?

  Sample rate

  Bit depth
• How do you calculate file size for a sound file?

  sample rate x bit depth x duration in seconds