1.3 Compression

Question 1

Compression

Answer 1

process of reducing file size without significant loss in quality, for reduced search time to find data and faster transfer (compressed files need less bandwidth than uncompressed)

Question 2

Lossless compression

Answer 2

Allows for the perfect reconstruction of the original data via utilising some type of replacement

Question 3

Examples of lossless compression

Answer 3

Bitmap (.bmp), vector graphics (.svg), .png images, run-length-encoding (RLE) for text file compression, database records

Question 4

Run Length Encoding

Answer 4

RLE is a form of lossless compression used for compressing text files and bitmap images. It reduces the file size by encoding sequences of consecutive identical elements into two values, run count and run value.

Question 5

Lossy compression

Answer 5

Irreversibly eliminates unnecessary data. Accuracy/quality lower than lossless. Size significantly reduced (~10% of that of lossless compression)

Question 6

Examples of lossy compression

Answer 6

sound files (.mp3), .jpeg images.

Question 7

Lossy compression: Perceptual Coding

Answer 7

parts of the sound wave less audible/discernible by human hearing is removed