Compression

Question 1

What is data compression?

Answer 1

When we make the file sizes smaller while trying to make the compressed file as true to the original as possible.

Question 2

What uses do compressing data files have?

Answer 2

• smaller files take up less storage space on a device
• streaming and downloading files from the internet is quicker as they take up less bandwidth.
• allows web pages to load more quickly in web browsers
• email services normally have restrictions on the size of the attachment you can send but compressing the file allows you to send the same content with a much smaller file size.

Question 3

What are the two types of compression?

Answer 3

Lossy and lossless compression

Question 4

What is lossy compression?

Answer 4

Works by permanently removing data from the file limiting the number of bits the file needs and so reduces its size.

Question 5

What is lossless compression?

Answer 5

Makes the file smaller by temporarily removing data to store the file and then restores it to its original state when it’s opened.

Question 6

What are examples of file types of lossy compression?

Answer 6

• MP3 (audio)
• AAC (audio)
• JPEG (image)

Question 7

What are examples of file types of lossless compression?

Answer 7

• FLAC (audio)
• TIFF (image)
• PNG (image)

Question 8

What are advantages of lossy compression?

Answer 8

• greatly reduced file size, meaning more files can be stored
• take up less bandwidth so can be downloaded and streamed more quickly
• commonly used - lots of software can read lossy files.

Question 9

What are disadvantages of lossy compression?

Answer 9

• loses data so the file can’t be turned back to original
• can’t be used on text or software files as these files need to retain all the information of the original
• worse quality than the original. But loss in quality is normally unnoticeable.

Question 10

What are the advantages of lossless compression?

Answer 10

• data only removed temporarily so there is no reduction in quality and should look and sound like original
• can be decompressed turned back into original
• used on text and software files

Question 11

What are the disadvantages of lossless compression?

Answer 11

• only a slight reduction in in file size so they still take up quite a bit of space on your device.