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1. Data Compression

   • Purpose of data compression
     • Reduce the physical file size of data on a file
     • Speed up data transmission times
     • Save strorage on primary storage drive (hard disk)
   • How Zipping compresses files
     • Include algrorithms capable of breaking down longer strings of data onto shorter ones
       • Basic
     • Then reassembles the longer strings of data later using what they retained from the shorter strings of data
     • Advanced
       • A algorithm is used to determine how to shrink the physical files size
         • Lossless compression (what WINZIP use)
           • Loseless compression works by temporarily removing data redundancy (repeated words/numbers/special charcters)
             • Lossless compression then replaces that redundant data with instructions
               • These instructions tell the system how much data repeats itself
                 • Example (data = FFFIII)
                   • Longer strings of data can be shortened into shorter strings E.G) F3I3
                     • Lossless compression enables the FULL RESTORATION OF A FILE to its ORIGINAL STATE when decompressed (UNZIPPED)
                       • Lossless compression doesn't lose a SINGLE BIT OF DATA
       • LOSSY Compression
         • Lossy compression PERMANENTLY removes redundant data to shrink the file size
           • Because lossy compression removes data permanenly
             • You cannot recreate the orginal file from the compressed file when decomopressing / unzipping
   • File formats
     • Bitmap
       • Retains all image details and quality at the expense of a large file size
       • Uncompressed image file format
       • Each pixel in a BITMAP images is represented by 8/16//24/32 bits (the colour depth)
     • JPEG (Joint photographic experts group_
       • Compressed image file format
       • Resolution can be reduced using compression methods (lossy / lossless)
       • Compression can cause the image quality to reduce (lossy compression)
         • The degree of lossiness can be altered to balnce the amount of quality lost and file size lost
       • lossy Compression causes the file size to reduce
     • GIF (Graphics interchange format)
       • File format used to display indexed colour graphics and images in HTML documents on the web
         • GIF can display up to a maximum of 256 colours
           • GIF is especially good at displaying grpahics with large blocks of colour and simple illustrations such as logo / icons
             • Gif isnt very good at displaying photogrpah images