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Data Representation (Images (Images are made up of pixels, Number of…
Data Representation
Images
Images are made up of pixels
Number of pixels does not alter in an image
More colours the more bits needed to store the image
Opposite is true
With 1 bit can have just 2 colours
2 bits = 2 to power of 2 which is 2 x 2 so 4 colours
3 bits = 2 x 2 x 2 = 8 colours
More bits per pixel more colour depth (means more colours used, greater sharpness)
Resolution
Concentration of pixels per unit
dpi = dots per inch
Metadata
additional information stored with the image such as date, time, height, width, resolution in dpi - remember this is the image properties
Instructions
Operator: Tells the CPU what to do
Operand: data linked to the Operator
Accumulator
Stores data currently being used by CPU
Address - location in the memory
Program Counter
Part of the CPU which controls the order of which task is next
Decode
Separates the operator and the operand
Sound
Sound waves are measured through sampling
Height / Amplitude of the sound wave is measured at regular intervals
More samples taken the closer to the original sound
More samples taken more data to store, increase file size
Opposite is true
Bit rate
Amount of space available to store sampled data per second
MP3 lower than a CD, higher bit rate better quality but more space needed to store
Binary - Base 2
Denary - Base 0
Hex - Base 16
Denary
1000, 100, 10, units
Units
0,1,2,3,4,5,6,7,8,9
Calculate the hex of 56
Work out the amount which 16 can go into the number so it is 48 which is 3 x 16 and remainder 8
So the Hex is
3 8
Hex
16, units
Remember that in hex you read the numbers differently
17 is not seventeen but is actually 1 x 16 +7 = 23
Calculate Denary of 3A
3 x 16 = 48
A = 10
48+10 = 58
3A = 58
Units
0,1,2,3,4,5,6,7,8,9,A, B, C, D, E, F
C = 12
Binary
128, 64, 32, 16, 8, 4, 2, 1
Adding binary
if adding 1 + 1 remember this is 10 as this is two in binary and then you carry forward
Overflow
this is when there are not enough bits to record the answer so you need to add another bit
Calculate the Binary of 58 as an 8 bit number
Use the column headings
128, 64, 32, 16, 8, 4, 2, 1
0 0 1 1 1 0 1 0
32+16+8+2 = 58
Units
1,0
Characters
Set of symbols / characters that a computer can recognise and understand
Unicode
16 bit though up to 32 bit
more characters available
includes ASCII as a subset of characters
ASCII
8 bit stores limited number of characters
does not deal with other languages