Data Representation Flashcards
Lowest to highest: terabyte, kilobytes, nibble, petabyte, gigabyte, byte, bit
Bit, nibble, byte, kilobyte, megabyte, gigabyte, terabyte, petabyte
FROM BYTE THEY ALL GO UP IN 1000
Binary arithmetic rules:
0+0=0
1+0=1
1+1=0 carry the 1
1+1+1=1 carry the 1
Advantages of hexadecimal:
-simpler to remember
-quicker to write or type
-less likely to make an error
-easy to convert between hex and binary
Overflow error
When the result of an addition is too large for the number of bits the computer works with.
Character set
A set of letters, symbols and digits that can be represented by a computer
ASCII
American standard code for information interchange. 128 characters into 7 bit binary codes
Unicode
To represent other characters for other languages, 16 bits, 65536 possible combinations
5 different file formats for images:
-JPG, joint photographic experts group
-BMP, bitmap, uncompressed
-GIF, graphics interchange format
-TIFF, tag image file format
-PNG, portable networks graphics, loddless compression
Pixel
The smallest identifiable area of an image
Resolution
The concentration of pixels within a specific area
Increasing the number of colours:
More bits per pixel = more colour combinations
Bit depth
The number of colours that can be represented. Each pixel can represent a finite number of colours, a pixel is attributed a number of n bits.
The number of combinations (2 to the n) dictates the bit depth
Colour depth
Colours depth = bit depth
Metadata
Data about data, e.g. author, date created, dimensions
Bitmap images
Bitmap images are made up of PICture ELement or pixels
Bitmap images
Bitmap images are made up of PICture ELement or pixels
Analogue sound
Continuous
Digital sound
Discrete, repeatedly measuring and recording the sound wave
Analogue to digital converters
Sounds must be converted into a digital form in order to be stored and processed by a computer
ADC
Analogue to digital converter
DAC
digital signals to outputs
Sound sampling
Sound sample is a measurement of a sound wave at a given time
Sampling rate
Frequency or sample rate per second affects the level of detail in the digital representation. Number of samples per second
Sound file sizes
Sample rate x bit depth x duration
Digitised sound quality:
-improves the more frequently we sample the sound
-improves the more accurate we record the wave height
Lossy compression
JPG, GIF, MP3. Permanently looses some data, cannot do back to original data.
Lossless compression
Will not lose any of the original data. Algorithm finds groups of repeating patterns and records that as the data.
Benefits of compression:
-smaller files=fewer packets=faster transmission time
-quicker to complete transmission
-reduces download time
-images inside web pages appear faster
-reduces space on disk/servers
Bit rate
Amount of data used to represent one second of audio
JPEG
Joint photographic experts group, lossy compression for digital images
