Things stored in computers are stored in binary.

Text

Character set - a defined list of characters recognised by computer hardware and software, each character represented by a single character.
Character sets are agreed standards.
ASCII is a 7-bit character set (128 combinations)
The extended ASCII character set is an 8-bit set (258 combinations)
(Includes arrow keys, delete key, space bar, shift…)
Unicode was originally a 16-bit set (some lesser used characters omitted)
It was then extended to 24-bit ( over 16 million combinations)
Each character is represented by a unique binary

Images

2 ways to store images:

• Bitmap - images made of coloured squares
• Vector - stores the maths to draw the shape

Metadata - data about data - like width, height, colour depth, colour pallette.
Start/end of image markers - where the list of pixels starts/ends
Dimensions - width and height of image
Colour depth (or pixel depth) - number of bits used to store each pixel, range of colours available in an image.

• Black and white - 1 bit
• Greyscale - 2 bit
• Colour scale - 24 bit
• More colours may require more bits.

Size of file: image height * image width * colour depth

Pixel density - number of pixels per inch
Resolution - the measure of pixel density

Sound

Analogue signal is converted to Digital signal
This is called analogue to digital conversion
Quality is Sample rate and Bit depth

• Sample rate - how frequently you record the amplitude of a sound wave
  • The more often sample is recorded the smoother the playback
  • Measured in hertz (Hz) (samples taken per second)
• Bit depth - number of bits needed to store sample
  • Measured in bits

Size of file = sample rate * duration * bit depth
In a graph, the x-axis represents time and the y axis represents amplitude