Wednesday 16 November 2016

Compression

  • The process of reducing the volume of data by applying compression technique is called Compression.
  • The reduced data is called compressed data.

Decompression

  • The reverse process of reducing the original data from compressed data is called Decompression.
  • The resulting data is called decompressed data.

Compression types

  • Compression divided into two types lossy and lossless see below figure.

Compression Utilities

  • There are normally used compression utilities Win RAR and Winzip.
    WinRAR
    • WinRAR is a trialware file archiver utility for Windows. It can create archives in RAR or ZIP file formats, and unpack numerous archive file formats. Itsupports lossless data compression.
    • Below figure shows the how to compress the a folder using WinRAR software.
    • Below figure shows the how to decompress the a folder using WinRAR software.
        Winzip
        • ZIP is an archive file format that supports lossless data compression. A .zip file may contain one or more files or directories that may have been compressed.
        • The .zip file format permits a number of compression algorithms, though DEFLATE is the most common. Zip files are compressed to save space.
        • Below figure shows the how to compress the a folder using Winzip software.
        • Below figure shows the how to decompress the a folder using Winzip software.

          Advantages of Compression

          • Reduce file size.
          • Provide security.
          • Save disk space.
          • Increase transfer speed at a given data rate.
          • Allow real-time transfer at a given data rate.

          Disadvantages of Compression

          • Lose the the data.
          • Lose the quality.
          • Some times we can forgot the password we lose the data.

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