Lossy vs Lossless

Question 1

What are the three key points for Lossy compression?

Answer 1

• Reducing the file size by removing data
• Original can’t be reconstructed
• Reduction in file size is very significant

Question 2

What are the four key points for Lossless compression?

Answer 2

• Reducing file size in a way which results in no data loss
• Allows the original file to be recreated exactly using redundant data
• If an item occurs multiple times it will only be stored and sent once as well as the information regarding where it was
• Dictionary coding made and sent along with the file allowing it to be recreated

Question 3

Where is Lossy compression used and what are the common file formats?

Answer 3

• Typically used for images and sound files

* Common file formats JPEG, MPEG and MP3

Question 4

Where is Lossless compression used and what are the common file formats?

Answer 4

• Used in text documents

* Common file formats ZIP, GIF, PNG