| | Compression : Lossy Methods | 
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Some compression methods lose some of the information from the original file when a file is compressed. Such methods are know as lossy because information is lost when compression takes place. The lost information can not be recovered when the file is decompressed.
Lossy compression methods can only be used for specific applications. Here are some common lossy compression methods :
| Method | Use |
| JPEG | JPEG files are compressed graphics files. You can select how much you want the file to be compressed by. The more a file is compressed the more information will be lost from the image. The JPEG compression algorithm tries to lose the least important information from the image. This is the information that a human is least likely to notice. |
| MP3 | MP3 files are highly compressed music files. The compression algorithm cleverly tries to identify parts of the music that a human would not hear and removes these from the compressed file to save space. |
Lossy compression methods can not be used to compress files such as computer software packages or documents. Any loss of data from such files would not be acceptable.
GCSE ICT Companion 04 - (C) P Meakin 2004