daltonism

Farbe
Color Blindness
Normal Spectral Sensitivity of Cones
100%
rrelative s
sensitiviity
75%
S
M
L
50%
25%
350
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400
450
500
550
600
2
650
700 nm
Color Blindness
recessive trait, located on X-chromosome
much more likely to occur in males
8%-13% males have deficiencies
<1% females have deficiencies
cause: some cones missing or defect
several types of color blindness exist
depends on which cones are missing
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Color Blindness
recessive trait, located on X-chromosome
XX
XX
XY
XY
XX
XY
XX
XX
XX
XY
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XX
XY
XX
XX
XX
XX
XX
XX
XY
XY
XY
XX
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XY
XY
XY
XX
XX
XY
XX
XY
XY
XY
XY
XX
XY
Color Blindness Forms
red-green blindness (~2% of people)
Daltonism, after its discoverer (1798)
Daltonism
deuteranopia (missing „green“ pigments)
protanopia
t
i (missing
( i i „red“
d“ pigments)
i
t )
blue-yellow blindness ((~0
0.02%
02% of people)
tritanopia (missing „blue“ pigments)
ll di
t ib t d across males
l and
d ffemales
l
equally
distributed
complete color blindness ((~0
0.001%)
001%)
achromatopsia (monochromacy)
no spectrally
t ll selective
l ti pigments
i
t att allll
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Normal Color Vision
tri-chromatic vision
f
fovea:
mainly
i l redd and
d green-cones, no rods
d
outside fovea: mainly
y rods,, some blue cones
fovea
…cones
…rods
retina
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Protanopia
[Protanopie]
protanopia = red blindness
red-cones
d
actt as green-cones
people
p
p have only
y di-chromatic vision
blue = normal, green + red → greyish yellow
neutral
t l point
i t (grey!)
(
!) = 492 nm
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Protanopic Sensitivity of Cones
100%
rrelative s
sensitiviity
75%
S
M
L
50%
25%
350
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400
450
500
550
600
8
650
700 nm
Deuteranopia
[Deuteranopie]
deuteranopia = green blindness
green-cones actt as red-cones
d
people
p
p have only
y di-chromatic vision
blue = normal, green + red → orange-yellow
neutral
t l point
i t (grey!)
(
!) = 498 nm
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Deuteranopic Sensitivity of Cones
100%
rrelative s
sensitiviity
75%
S
M
L
50%
25%
350
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400
450
500
550
600
10
650
700 nm
Tritanopia
[Tritanopie]
tritanopia = blue blindness
bl
blue-cones
are missing
i i ((very rare))
people
p
p have only
y di-chromatic vision,,
but blue is the least important color (# cones)
blue → grey,
grey green + red = normal
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Tritanopic Spectral Sensitivity of Cones
100%
rrelative s
sensitiviity
75%
S
M
L
50%
25%
350
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400
450
500
550
600
12
650
700 nm
Achromatopsia
[Achromasie]
achromatopsia = total color bindness
allll cones are missing
i i (very
(
rare: ~1/100.000)
1/100 000)
all colors → grey
g y
blind fovea → no sharp images (poor acuity)
extremely
t
l sensitive
iti to
t bright
b i ht light
li ht
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Achromatopsia: No Cones
100%
rrelative s
sensitiviity
75%
S
M
L
50%
25%
350
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400
450
500
550
600
14
650
700 nm
Achromatopsia
[Achromatopsie]
normal vision
achromatic vision
fovea contains no cones (and no rods)
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Weaker Color Deficiencies
normal: sensitivity of pigments is varying
protanomaly: red-weakness (~1% of men)
deuteranomaly: green-weakness (~6% of men)
tritanomaly: blue-weakness (~0.01% of people)
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Comparison
normal
deuteranopia
protanopia
tritanopia
achromatopsia
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Comparison Programs
www.paciellogroup.com/resources/contrast-analyser.html
www.vischeck.com/vischeck
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CB Color Circle
for red-green blindness vs. „normal“
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CB Painting
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Copy of a Painting by a Red-Green Blind
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Comparison
< normal
deuteranopia >
protanopia >
< tritanopia
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Comparison
< normal
deuteranopia >
protanopia >
< tritanopia
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Comparison
normal / deuteranopia / protanopia / tritanopia
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Finding Raspberries
normal
deuteranopia
protanopia
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tritanopia
Color Deficiency Examples
normal
protanopia
source:
www.graphics.cornell.edu
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deuteranopia
26
tritanopia
Another Deuteranopia Example
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Color Deficiency/Blindness Tests
Ishihara Color Blindness Test (1917)
4 kinds of test plates
transformation plates
anomalous
l
observers
b
give
i different
diff
responses
disappearing digit (vanishing) plates
only normal observers recognize a pattern
hidden digit plates
only anomalous observers see a pattern
qualitative plates
to classify protan from deutan and
mild from severe anomalous color perception
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Color Blindness Tests
apart from color test charts, anomaloscopes
are used to test for the various forms of CB
source: Daniel Flück
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Anomaloscope
subject has to mix
red and green to
match a given
mono-chrome
h
lilight
ht
t
l people
l use ttoo much
h red
d
protanomal
deuteranomal people use too much green
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