Data storage and compression

Any one from: • Kilobyte is an SI measurement, whereas kibibyte is an International Electrotechnical Commission (IEC) measurement • Kilobyte is equivalent to 1000 bytes, whereas a kibibyte is equivalent to 1024 bytes • Kilobyte is equivalent to 10³ bytes, whereas a kibibyte is equivalent to 2¹⁰ bytes • Kilobyte is a base 10 measurement, whereas a kibibyte is a base 2 measurement

• kilobyte (kB) - 10³ • megabyte (MB) - 10⁶ • gigabyte (GB) - 10⁹ • terabyte (TB) - 10¹²

• Less internet bandwidth is used when files are downloaded/uploaded • Transfer time is faster • Reduced file size / less storage space is needed • Smaller files reduce congestion on the internet

• Reduces file size without deleting any data • When compressed data is uncompressed, it is restored completely to the original file

Algorithms look for areas of redundancy where same data is stored many times, grouping this data into one reference (this is an example of run-length encoding)

Successful uses • Text files • Graphic files with a low colour depth Less successful uses • Audio files • 24-bit colour files

• Reduces file size by deleting some data • Changes made are irreversible and original form cannot be retrieved

• Image files - algorithms analyse image and find areas where there are slight differences, give these area same value and the file is rewritten with less bits • Digital sound recordings - small variations in frequency, tone and volume are removed, human ear cannot detect these small differences

Successful uses • Image files • Digital sound recordings Less successful uses • Text files • Executable software

• JPEG • MP3

3c3w2c6w3c