Compression

Question 1

What are the two types of compression?

Answer 1

• Lossy ( Un-necessary information is removed from the original file
• Lossless ( Retains all information required to replicate exact original file

Question 2

Why is compression needed?

Answer 2

• Reduce the storage space of files on disk

* Allows faster transmission of data with smaller file sizes

Question 3

How does lossy compression work?

Answer 3

• Removing non-essential information from the original file

Question 4

What are disadvantages of using lossy compression?

Answer 4

File quality is sacrificed

Question 5

How does lossy compression of sound work?

Answer 5

Removes frequencies too high for most to hear, and removes quieter sounds that are played at the same time as louder sounds.

Question 6

How does lossless compression work?

Answer 6

• Recording patterns in data rather than the actual data.
• Using patterns and a set of instructions on how to use them, the computer can reverse the procedure and reassemble an image, sound or text file to an exact accuracy with no loss of data

Question 7

What is a disadvantage of lossless compression?

Answer 7

Final file size is much bigger than lossy compression

Question 8

Where might lossless compression be used?

Answer 8

• Documents where missing words could lead to confusion over the information available
• Programs, as missing characters and lines can result in errors in the program.