Data Representations

Binary Number
1. Binary is base 2 and can be represented as a 1 or 0.
2. Conversions
  1. 1 or 0 = 1 bit
  2. 4 bits = 1 nybble
  3. 8 bits = 1 byte
  4. 1,024 bytes = 1 kilobyte
  5. 1,024 kilobytes = 1 megabyte
  6. 1,024 megabytes = 1 gigabyte
  7. 1,024 gigabytes = 1 terabyte
3. Binary Denary conversions
  1. use table: 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1
    1. Denary to binary
      1. take the denary number and minus the largest number from the table, without making the denary number negative. at a 1 under the number from the table, and repeat until the denary number = 0
    2. Binary to denary
      1. in each slot that a 1 is present add the number it corasponds to the total
Graphics
1. Bit Map Image
  1. Bit map images are made up of pixels
  2. Bit map uses bits to represent colours
    1. 1 bit can use 2 colours
    2. 2 bits can use 4 colours
    3. 4 bits can use 16 colours
    4. 8 bits can use 256 colours
  3. Working out how much data is needed for bit map images
    1. Bits per Pixel x Resolution = bits needed to store image
  4. Resolution
    1. Width x Height of image
2. Vector Image
  1. Vector images do not store data by pixels
  2. Vector Images store data as instructions such as:
    1. Colour line
    2. Thickness of line
    3. Fill Colour
    4. Distance from origin
    5. Coordinances of origin
  3. Advantages:
    1. Can be scaled without loss of quality
    2. Use less storage space
3. Metadata
  1. Term refers to "Data about data"
  2. Tells about key properties needed to display the image
    1. Resolution
      1. Height
      2. Width
    2. Colour depth
Hexadecimal
1. Hex uses base 16 for its numbers
2. numbers up to 9 are the same in hex as in denary, however 10-15 use the alphabet A-F
3. Hex uses the table :16 | 1
  1. to convert Denary to hex / by 16 for the first value, then use the remainder for the second value, then convert the numbers into hex.
  2. To convert hex to denary: if any letters are present, covert them to numbers, the the first number, X by 16 then add the second number
ASCII
1. Stands for American Standard Code for Information Interchange
2. ASCII is used to represent all alphabetic upper and lower case characters and 32 punctuation and other symbols, which can then be stored as binary
Sound
1. Sound waves are analogue, making it hard for computers to store them as there is no specific measurable value so sound is stored digitally
  1. The analogue wave is sampled then a digital representation of the original sound is saved.
    1. The higher the sampling rate the better the quality of the sound is, however this needs more storage space.
      1. The recommended sample rate is 48kHz(48,000 samples per second) because above 50kHz humans cannot tell any difference so cannot benefit from better quality.

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Data Representations

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	Created by hcl.wong over 10 years ago