Week 11: image compression.

Question 1

what is image compression

Answer 1

reducing the size of an image file without/with loss of image quality

required for large files, multiple images, legal requirements (storage)

Question 2

what are the two types of image compression

Answer 2

lossless:
no visible loss of info.

Lossy:
no/yes loss of info

Question 3

what is lossless/ how does it operate

Answer 3

no visible loss of info, removes redundant info

uses run length coding
huffman coding
lwz coding

Question 4

what is lossy compression

Answer 4

possible/ no loss of image info

reduces spatial resolution or contrast resolution

i.e from 10 bit into 8 bit
loss of info will occur if histogram spreads well over a smaller bit total. dependant on dynamic range.

Question 5

what do JPEG images use for compression?

Answer 5

use both lossless and lossy