Data Representation

Binary conversions
1. Adding binary
  1. 1011 +1111 11010
  2. If it's a double 1 it's makes 1 and you carry another 1
  3. If it's a 1 and a 0 you put a 0 and carry the 1
2. Hexadecimal and Deanery
  1. 0-9 are numbers 10-15 are A-F
  2. 10110111
    1. First split it down the middle
      1. 1011|0111
    2. Then it becomes a nibble each side
    3. Add up each nibble
      1. 11|7
    4. Then see if any are to be converted into letters
      1. 11=B
    5. You answer is B7
3. ASCII code
  1. A=65 a=97
  2. ASCII code does represent emojis Unicode does
4. Bits/nibbles
  1. Bit is a single binary integer
  2. 4 bits make a nibble
  3. 8 bits make a bite
Binary images
1. Pixels
  1. Pixels are the picture element so what the screen is made up of
  2. You can find out how many pixels there are but finding the area of the screen
2. Black+white images/ colour images
  1. If it's a black and white image 1=black and 0=white
  2. For colour images black would be the highest integer and white would be the lowest
  3. A bit depth is how many bits are used to represent the colours or the colour depth
  4. 2 to the power of colours used x W x H = bit depth
3. Meta data
  1. The resolution of the picture and colour depth
4. Lossy/lossless compression
  1. Lossy compression
    1. Reducing the file size
    2. But you can't get it back once it's deleted
    3. JPEG uses lossy compression
  2. Lossless compression
    1. Reducing the file size
    2. You can get the data back if you want
    3. PNG uses lossless compression
  3. Lossless and lossy compression is when the photo becomes compressed and the quality of the photo goes down
Sound representation
1. The wave
  1. Amplitude is how loud the sound is
  2. Wavelength is the distance between a on one wave and the same point on another wave
  3. It's easier to measure from the crest of one wave and the same point on the next wave
2. Frequency and pitch
  1. Frequency is the pitch of a sound the closer the wave the higher the pitch. The longer the wave the lower the pitch
  2. The frequency is measured in Hertz (Hz), Kilohertz (KHz) and Gigahertz (GHz)
  3. A frequency of 1 Hz means one wave per cycle per second. A frequency of 10 Hz means 10 wave cycles per second where the cycles are short and closer together
3. Sound on a computer
  1. Sound created on a computer exist as digital information encoded as audio files
  2. Stages of making digital sound
    1. 4. The computer then displays the digitalised sound for manipulation
    2. 3. An analogue to digital converter digitalises the electrical voltage to bytes of information
    3. 2. Microphone changes the air pressure into electrical voltage
    4. 1. Microphone measures changes in air pressure

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Data Representation

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	Created by Melissa Norwood about 7 years ago