vision and colour Flashcards
iris
controls how much light comes in
lens
transmits incoming light to the retina adapting the focus nearer and farther
retina
photoreceptor (light sensor) layer
fovea
area of high density on the retina
rods
sensitive to light intensity
cones `
sensitive to light frequency
what are the two types of photoreceptors
rods
cones
central retina
only has cones
high density; perception of form
3 types of cones; colour perception
short cones
blue light sensitivity
peripheral retina
has more rods which detect light and motion
medium cones
green light sensitivity
long cones
red light sensitivity
how do we see colour
cones get hit by light at a certain wavelength and the retina does minus calculations to convert that into a biological signal
fovea vision
allows perception of detail
high resolution and colour sensitivity
what is the degree for fovea vision
1-2
what is the degree for peripheral vision
200 degrees left and right
130 degrees up and down
how do peripheral and fovea vision operate together
in parallel
peripheral vision
detection of stimuli; motion and light changes
fixations
we move our eyes to align with objects of interest to get details
how much time do we need for fixations
200ms before moving to the next fixation
saccades
the fast movement between each fixation
how much time do we need for saccades
20-30ms
what is our viewing range without head movements
30 degrees down and 20 degrees left and right
why do we need head movements when moving our eyes
helps us keep the eyes in a comfortable viewing range
cyclopean model
whilst we have two eyes we never see two different images as theyre fused into one
binocular model
our eyes are like two cameras at an offset from eachother
what is binocular vision and what is it caused by
images from both eyes are slightly different
parallax
binocular disparity
the difference between both eyes gives a hint to the depth of an object
vestibular
senses how much you rotate your head
what causes simulator sickness
when theres a conflict between physical and visually percieved motion
what gives us a sense of motion
when we move our heads a flow of light is created in the retina
vergence
depending on the distance of the fixation the eyes turn towards eachother in the head so the lines of sight are aligned
accommodation
eye lens changes shape to focus on an object with respect to the optics of the system
what is the colour of an object
the wavelength of light that it doesnt absorb
colour models
help us describe colours
what are the 3 main colour models
rgb
cmyk
hsv
cmyk
usually printers
reflects only a set of frequencies
key = black, dark/light, depth/shading
hsv
hue; where it is on the spectrum
saturation; purity, from grey to pure
value; lightness/intensity
how does contrast affect our perception
relative contrast can make colours look different
