GCSE Computing/the differences between lossy and lossless compression
Contents
Lossless versus lossy compression[edit]
Summary[edit]
It is often necessary to compress a file to make it small enough to be used - for example making a music file small enough so that enough can be stored on an iPod. There are two main possibilities:
- Lossless
- These are used to make a file a smaller size but without losing any of the information. Using this method you can always get back to the original file
- Lossy
- Sometimes some loss of quality is acceptable. For example the human ear cannot hear all frequencies, so a file format that throws away parts that people can't hear may end up with a smaller file, but it is not possible to get back to how exactly the original music sounded.
Which format to choose?[edit]
The only real reason for choosing a lossy format is because the file would be too big if you used a lossless one. For example, a lossless picture may be too big to download in a sensible amount of time, or you could store many less tracks on an iPod if you used a lossless format instead of AAC or MP3. Another factor to choose lossy or lossless compression may be the computational power needed (and the time).
Examples[edit]
Lossless Compression[edit]
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Wikipedia has related information at Portable Network Graphics |
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Wikipedia has related information at Tagged Image File Format |
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Lossy Compression[edit]
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Wikipedia has related information at MP3#Development |
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Wikipedia has related information at JPEG#JPEG compression |
