Compression Quiz

Which type of compression ensures that all of the data is kept?

• Lossless

• Lossy

Lossy compression removes data that isn't needed...

• True

• False

Compression makes file sizes...

• Bigger

• Smaller

• Keeps them the same

An advantage of lossless compression is...

• All data is lost

• The file size stays the same

• All of the important data is kept

A disadvantage of lossless compression is...

• There is a big reduction in file size

• There is only a slight reduction in file size

• There is no reduction in quality

• Cannot be used on text or software files

The correct encoding of the letter C in this tree is...

• 11

• 10

• 01

• 00

Huffman trees use the _______________ of each character to work out their encoding.

• Frequency

• Order in ASCII

• Number value

How do you calculate the number of bits of a body of text in ASCII?

• Number of characters * 7

• Number of characters (including spaces) *7

• bits in Huffman * 7

• bits in Huffman / 7

Which formula shows how to work out the percentage a file has been compressed by?

• bits in (Huffman *7) /100

• bits in ASCii - bits in Huffman

• difference in bits / bits in ASCII * 100

Data compression is important for websites because:

• Your webpage will load faster
• Compressed images look better