week 8: perception/contrast eye

Question 1

what is brightness

Answer 1

subjective descriptor of light.

the eyes are continually adapting therefore we can’t use them to measure brightness

Question 2

what is luminance

Answer 2

measure of amount of light energy received by observer (measured in lumens (Lm))

Question 3

what is webers law

Answer 3

as luminance changes, human eye can’t detect the same changes until apron 2% has changed

humans can detect small changes to dark intensity rather before we can detect small changes to bright intensities

Question 4

what is just noticeable difference (JND)

Answer 4

amount of luminance light intensity change that has occurred before we notice it

Question 5

how many shades of grey can we detect

Answer 5

30

Question 6

what is contrast sensitivity

Answer 6

measured in JND. we can’t detect contrast at high and low brightness levels (its harder)