03 Compression

Question 1

Effect of reducing the amount of data

Answer 1

Data is sent more quickly
Less bandwidth is used
Buffering is less likely
Less storage required

Question 2

Lossy

Answer 2

Non-essential data is permanently removed

Question 3

Lossless

Answer 3

Patterns in the data are spotted and summarised in a shorter format without permanently removing any information

Question 4

Lossy compression

Answer 4

Removes data permanently to reduce file size
Tries to reconstruct an image without any missing data.

Question 5

How does Lossless compression work

Answer 5

Using this pattern information, a new file can be replicated exactly without any loss of data
The reduction in file size is less than for lossy compression

Question 6

Run length encoding (RLE)

Answer 6

A basic method of compression that summarises consecutive patterns of the same data
Works well with image and sound data where data could be repeated many times

Question 7

Dictionary compression

Answer 7

Spots regularly occurring data and stores it separately in a dictionary