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Data Representations
- Binary Number
- Binary is base 2 and can be
represented as a 1 or 0.
- Conversions
- 1 or 0 = 1 bit
- 4 bits = 1 nybble
- 8 bits = 1 byte
- 1,024 bytes = 1 kilobyte
- 1,024 kilobytes = 1 megabyte
- 1,024 megabytes = 1 gigabyte
- 1,024 gigabytes = 1 terabyte
- 1 or 0 = 1 bit
- Binary Denary
conversions
- use table: 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1
- Denary to binary
- 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
- 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
- Binary to denary
- in each slot that a 1 is present add the
number it corasponds to the total
- in each slot that a 1 is present add the
number it corasponds to the total
- Denary to binary
- use table: 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1
- Binary is base 2 and can be
represented as a 1 or 0.
- Graphics
- Bit Map Image
- Bit map images are
made up of pixels
- Bit map uses bits to
represent colours
- 1 bit can use 2 colours
- 2 bits can use 4 colours
- 4 bits can use 16 colours
- 8 bits can use 256 colours
- 1 bit can use 2 colours
- Working out how much
data is needed for bit map
images
- Bits per Pixel x Resolution = bits needed to store image
- Bits per Pixel x Resolution = bits needed to store image
- Resolution
- Width x Height of image
- Width x Height of image
- Bit map images are
made up of pixels
- Vector Image
- Vector images do not
store data by pixels
- Vector Images store
data as instructions such as:
- Colour line
- Thickness of line
- Fill Colour
- Distance from origin
- Coordinances of origin
- Colour line
- Advantages:
- Can be scaled without loss of quality
- Use less storage space
- Can be scaled without loss of quality
- Vector images do not
store data by pixels
- Metadata
- Term refers to
"Data about data"
- Tells about key properties
needed to display the image
- Resolution
- Height
- Width
- Height
- Colour depth
- Resolution
- Term refers to
"Data about data"
- Bit Map Image
- Hexadecimal
- Hex uses base 16 for
its numbers
- numbers up to 9 are the same
in hex as in denary, however
10-15 use the alphabet A-F
- Hex uses the table :16 | 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.
- 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
- 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.
- Hex uses base 16 for
its numbers
- ASCII
- Stands for American Standard Code for
Information Interchange
- 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
- Stands for American Standard Code for
Information Interchange
- Sound
- Sound waves are analogue, making it hard for
computers to store them as there is no specific
measurable value so sound is stored digitally
- The analogue wave is sampled then a digital
representation of the original sound is saved.
- The higher the sampling rate the better the quality of the sound
is, however this needs more storage space.
- 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.
- 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.
- The higher the sampling rate the better the quality of the sound
is, however this needs more storage space.
- The analogue wave is sampled then a digital
representation of the original sound is saved.
- Sound waves are analogue, making it hard for
computers to store them as there is no specific
measurable value so sound is stored digitally
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