Lossy And Lossless

 Lossy compression

◼Lossy compression removes some of a file’s original data in order to reduce the file size. 

◼This might mean reducing the numbers of colours in an imagea or reducing the number of samples in a sound file. 

◼This can result in a small loss of quality of an image or sound file.

◼A popular lossy compression method for images is the JPEG, which is why most images on the internet are JPEG images.

 ◼A popular lossy compression method for sounds is MP3.

 

◼Once a file has been compressed using lossy compression, the discarded data cannot be retrieved again.

Lossless compression

◼Lossless compression doesn’t reduce the quality of the file at all.

 

◼No data is lost, so lossless compression allows a file to be recreated exactly as it was when originally created.

◼There are various algorithms for doing this, usually by looking for patterns in the data that are

repeated.

 ◼Zip files are an example of lossless compression.

◼The space savings of lossless compression are not as good as they are with lossy compression.