Compression
Computer Science: OCR A Level, topic 3.1.1
Types of Compression
Representing audio, images, and especially video take up a lot of secondary storage space. Compression helps to reduce the size of these files so that we can store more data.
Lossy compression
- An algorithm is applied to remove unnecessary detail from the original file.
- Some data is permanently lost, but enough remains so that the file is still useful and there is barely a noticeable difference.
- Lossy compression results in dramatic file size reduction.
Lossless compression
- None of the original data is lost.
- An algorithm can be used to perfectly restore the original file when needed.
- This is especially useful for executable files, where all of the data is necessary.
- Lossless compression causes file size to reduce moderately.
Test yourself on Compression
Which compression method results in the best size reduction?
For which of these is lossy compression appropriate?