Compression

Question 1

What does compression mean?

Answer 1

• Making a file smaller.

Question 2

Benefits of compression:

Answer 2

• Files take up less storage space so more files can be stored.
• Files can be transferred quicker because they are smaller.
• Files can be read from or written to quicker.

Question 3

Lossy Compression - what does it do, how does it work, what are some examples where it is used?

Answer 3

• Uses an algorithm to analyse a file and remove data that cannot be heard or seen by humans.
• This reduces the size of the file.
• Further lossy compression removes data that humans can see/hear.
• Removes data permanently, so the file can never return to its original form.
• Used with images, audio and video.

Question 4

Lossless Compression - what does it do, how does it work, what are some examples where it is used?

Answer 4

• Reduces the size of a file without permanently removing any data.
• Because of this, the file is returned to its original form when decompressed, so no quality is lost.
• The finished file size is usually larger with lossless than with lossy because no data has been permanently removed.
• Used with files that wouldn’t work it data was not removed for example executable files (programs, games) and word documents.