1.3.3 DATA COMPRESSION

Question 1

Why do files need to be compressed?

Answer 1

• A higher bandwidth would be needed to transmit the uncompressed file.
• A greater amount of storage space would be required for storing uncompressed files.

Question 2

Benefits of compression?

Answer 2

• less bandwidth required
• Compressing the file reduces size, hence, less storage space is required

Question 3

What is lossless compression?

Answer 3

Lossless reduces the file size without permanent loss of data, e.g., run-length encoding (RLE)

Question 4

What is lossy compression?

Answer 4

• Loss compression reduces the file size by permanently removing the data, e.g., reducing resolution or color depth, reducing sampling rate or resolution.

Question 5

What are common lossy file compression algorithms?

Answer 5

• JPEG
• MPEG - 3 (MP3)

Question 6

How is lossy compression used?

Answer 6

• It is used to compress music files, video files & photos.
• It is used for files where removing certain bits doesn’t detract from the quality.

Question 7

How does LOSSY compression actually work in an image/sound file?

Answer 7

• In an image, lossy compression may reduce the image resolution or the color depth (bit depth).
• In a sound file, lossy compression may reduce the sampling rate or the sampling resolution.

Question 8

What are the advantages of LOSSY compression?

Answer 8

• It reduces the file size more than lossless, hence saves more memory.
• It will require less time and less bandwidth if transmitted.

Question 9

What are the disadvantages of LOSSY compression?

Answer 9

• The quality of the image, audio, or video will be reduced.
• The original file cannot be restored.

Question 10

What is LOSSLESS compression?

Answer 10

• Lossless compression is designed to lose none of the original detail.
• It allows the original file to be re-created exactly when uncompressed.
• It can compress and reduce data to about 50% maximum.

Question 11

How is LOSSLess Compression used?

Answer 11

• It is used in compressing text files.
• It is used where the loss of any data would be disastrous, such as a spreadsheet file.

Question 12

What are the advantages of LOSSLESS compression?

Answer 12

• It reduces the file size, hence saves memory.
• The original file can be restored.

Question 13

What is the only DISADVANTAGE of LOSSLESS COMPRESSION?

Answer 13

• It reduces the file size lesser than lossy compression.