Transcript Colour quality description of LED light sources for

Colour vision
János Schanda
Virtual Environments and Imaging
Technologies Laboratory
University of Pannonia
Overview

Human trichromacy
The human retina
 Colour deficiencies
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Path from the retina to the cortex
Brightness versus luminance
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The fifth light sensitive cell in the human
retina
Visibility
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Perceiving details
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Rapid identification
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Brightness/lightness evaluation
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Hue & colourfulness evaluation
The eye
The structure of the eye
The human eye
Fovea: only cones,
covered by the
macula lutea,
yellow
pigmentation.
Foveola: central
parto of fovea, only
L and M cones,
blue colour blind.
Artist’s view of the structure of the
foveal retina
Light perception
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Imaging the exterior
world on the retina
The retina and its most
sensitive part the fovea
The receptive cells
The structure of the retina
Cones and rods
Distribution of rods and cones
within the retina
Spectral sensitivity of the three cone types, logarithmic scale
1
log cone action sensitivity
0
-1
-2
L-cone
-3
M-cone
-4
S-cone
-5
-6
-7
-8
350
450
550
wavelength, nm
650
750
Fundamental colour
matching experiment
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Wright and
Guild
experiments
Different
fundamentals
Transformed
to common
basis
R, G, B primary based CMFs
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R: 1 unit, 700
nm
G: 4,5907
units,
546,1 nm
B: 0,0601
units,
435,8 nm
Background information
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CIE 1931 2° standard colorimetric
observer and Colour Matching
Functions (CMFs)
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CIE 1924 spectral luminous efficiency
function
CIE 1964 10° standard colorimetric
observer and CMFs
CIE TC 1-36 report
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Fundamental Chromaticity Diagram with
Physiological Axes - Part 1: CIE 170:2006
L,M,S cone fundamentals
 Photopigment absorption spectrum
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Macular pigment absorption
Field size dependence
Sties-Burch colour matching
functions
l
3.5
3.0
2.5
_
tristimulus values
r(λ)
2.0
1.5
_b(λ)
_
g(λ)
1.0
0.5
0.0
-0.5
350
400
450
500
550
600
650
w avelength (nm)
700
750
800
850
Macular pigment optical density
0.4
Optical Density
0.3
o
2
0.2
o
10
0.1
0.0
350
400
450
500
w avelength (nm)
550
600
Lens and ocular media optical
density
2.5
Optical Density
2.0
1.5
1.0
0.5
0.0
350
400
450
500
550
w avelength (nm)
600
650
700
Derived photopigment low density
absorbance
2.5
Optical Density
2.0
1.5
1.0
0.5
0.0
350
400
450
500
550
w avelength (nm)
600
650
700
Complete path of getting to the
corneal level cone fundamentals
Lens
pigment
o.d.
Stiles
& Burch
Reference
10° cone fundame ntals
Cone photo
pigment o.d.
 10 deg
 l10(), m10(), s10()
Retina
Cornea
CMFs
 10 deg
Macular
pigment o.d.
 10 deg
Photopigment
low density
spectral
absorbance
Ai,o(L-pig ment)()
Ai,o(M-pig ment)()
Ai,o(S-pigment)( )
Fitted
CMFs
 2 deg
Cone photo
pigment o.d.
 2 deg
2° cone fundame ntals
 l2(), m2(), s2()
Lens
pigment
o.d.
Macular
pigment o.d.
 2 deg
2° cone fundamentals
Spectral sensitivity of the three cone types, linear scale
Transformation to XYZ-like CMFs
for the 2°observer
(tentative equation!)
CIE 2° and cone fundamental
derived (CFD) 2° CMFs
2
1.8
1.6
trisitm.values
1.4
x¯(λ)
y¯(λ)
1.2
z¯(λ)
1
0.8
xF¯(λ)
yF¯(λ)
0.6
zF¯(λ)
0.4
0.2
0
350
400
450
500
550
600
wavelength, nm
650
700
750
800
Standard
and cone
fundamental
chromaticity
diagram
(Insert: DE per
wavelength)
D(u’,v’) differences if the CIE 2° observer is used
or the tentative CMFs of CIE TC 1-36
4
5
6
CFD-CMF
0,025
0,038
0,025
0,011
0,013
0,010
0,013
0,003
0,002
Calculated chromaticities using
CIE 1931 2° CMFs
0,6
0,005
0,002
0,003
7
8
0,017
0,002
0,009
0,003
9
0,006
0,004
#5
#4
#6
#9
#8
0,5
#1
#3
v'
1
2
3
CIE 1931
2°
0,4
#7
RGB LED
Visual average
Broad-band reference
#2
0,3
0,0
0,1
0,2
0,3
0,4
u'
Dom. wavelength: 626 nm,
525 nm, 473 nm
0,5
0,6
CIE u’,v’ differences in case of CIE 2°, TC1-36 2°
(Fundamental CMFs) und modified 2° Őbserver
(Mod.Fund. CMFs)
Chromaticity differences using different CMFs (CIE 1976 u'v')
0,050
0,045
CIE 1931 2° CMFs
Fundamental CMFs
Modified Fundamental CMFs
0,040
0,035
0,030
0,025
0,020
0,015
0,010
0,005
0,000
Sample
#1
Sample
#2
Sample
#3
Sample
#4
Sample
#5
Sample
#6
Sample
#7
Sample
#8
Sample
#9
Retinal processing
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Cone vision -> foveal
vision
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Long wave -LMedium wave -MShort wave -Ssensitive
cones
New signals are created
already at retinal level
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Receptor cells produce
analogue potential
difference for excitation
At output (ganglion cell)
level fireing frequency
signal is produced
Antagonistic colour channels and the
brightness/lightiness channel
ON and OFF signals
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The ON centre
bipolar cell is
activated by the
cone signal
The OFF centre
cell gets activated
as the light
decreases.
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Differences in the
ganglion cell
fireing rate
Receptive fields, functional diagram
Receptive fields
Neural signal generation
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H1 &H2: horizontal cells,
participate in the antagonistic
signal processing
B: bipolar cells, participate in
the centre/surrounding
antagonistic process (ON and
OFF cells)
G: ganglion cells
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MC: magnocellular (ON and OFF
cells)
PC: parvocellular (2 ON and OFF
cells)
KC: koniocellular (2 ON cells)
Neural pathway - 1
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Achromatic channel:
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L + M cone signal
Sensitive on edges, contrast
Luminance like spectral responsivity
 flicker photometry
 small step brightness comparison
Rapid signal transmission
Neurons leading to magnocellular layers
Standardised visibility functions
1.2
V(l)
VM(l)
1
V´(l)
y(l)10
rel. sensitivity
0.8
0.6
0.4
0.2
0
350
400
450
500
550
600
wavelength, nm
650
700
750
800
Neural pathways -2
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Parvocellular: L-M cone signal
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Fine details, slow
Red – green antagonistic structure
Koniocellular: S – L, M-S cone signals
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Slow
Yellow – blue antagonistic structure
Way of the colour signal from
the retina to the brain
Lateral geniculate body
Chromatic adaptation
Received from Prof. Hunt
Parsing of information
Visual areas of the cortex
Brightness – luminance
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L+M signals: luminance like
All three cones participate in brightness
perception
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Possible rod contribution to brightness
Intrinsically photosensitive Retinal Ganglion Cells
might contribute too by pupil diameter regulation
Rod vision -> scotopic and peripheral vision
Mesopic vision: interaction between rod and
cone receptors
Brightness description
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Photopic system
Scotopic system
x(λ)input y(λ )input z(λ)input
V'(λ )input
Scotopic
luminance
L'
Photopic
luminance
L
Cy/b Cr/g
H elm holtz-K ohlrausch
effect
Purkinje effect
a=
1-a
L
L+ a
a
(L') · (L) ·10
(adaptation coefficient; achromatic)
c
cc =a
= acc·[ f(x,y)
f(x,y) - 0.078]
1/2
kL
ac = 1/2
L +b
(adaptation coefficient; chromatic)
Equivalent luminance, Leq
Parameters:
CIE supplementary
system of
photometry, CIE
200:2011
a = 0.05 cd/m2, b = 2.24 cd/m2, k = 1.3, f(x,y)=Nakano (1999)
Luminance and brightness
160,00
140,00
120,00
rel. resp.
100,00
V(l)
80,00
Vb2(l)
60,00
Landolt1,2,4,6
40,00
20,00
0,00
400
-20,00
500
600
wavelength, nm
700
Sp. sensitivity of different
receptors
rel. sensitivity, arb. units
1
0.8
0.6
Gall-Circ
l¯(λ)
0.4
m¯(λ)
s¯(λ)
0.2
0
350
400
450
500
550
wavelength, nm
47
600
650
700
Binary – broad band match
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Broad-band:
tunable LED
source
(curtasy of
Zumtobel)
with 470 nm
blue
component
Two
component:
cyan + deep
red LED
25 observers
1.00
rel. intensity, arbitr. units
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0.80
0.60
0.40
0.20
0.00
400
450
500
550
600
wavelength, nm
2LED
Zumtobel
48
650
700
Matching point of binary-broadband match
0.9
0.8
0.7
0.6
y
0.5
0.4
0.3
0.2
0.1
0
0
0.2
0.4
0.6
x
49
0.8
View of the double booth
Nonfluorescent
white paper
placed on
black
background,
no colour in
field of view.
50
Relative power in the circadian-, S-cone and Rod sensitivity
bands comapred to the luminous flux
LED source
Circadian/lum.flux
S-cone/lum.flux
rod/lum.flux
2 LED combination
0,73
0,39
0,22
0,23
1,1
0,56
Zumtobel
adjustable source
Results of brightness comparison of 2 LED and “Zumtobel”
source illuminated samples
Number of Persons
4
(1<35Y,0>65Y)
15
Rel. brightness
(2 LED/”Zumt.”
0,86
(1<35Y,4>65Y)
1,20
% st. dev.
2,1
9,9
6
(1<35,1>65Y)
1,02
3,1
Observers found chromatic mismatch for equal chromaticity and
luminance setting (Instr. Syst. CAS 140CT+TOP100 radiance probe)
51
Visual acuity
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Landolt-C investigation
The fovea is also in the mesopic range V()
sensitive
Subjective evaluation is mainly based on foveal
vision
Summary
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Foveal task: V()
Peripheral task: V´()
Brightness evaluation:
Equivalent luminance
Colour deficiencies
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Dichromat
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Anomalic trichromat
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protanope
deuteranope
tritanope
protanomal
deuteranomal
tritanomal
Monochromat
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cone monochromat
rod monochromat
Normal trichromat
Dichromat
Red-green colour
deficient: cone
density normal,
but has only S
and M cones
Dichromat
Red-green colour
deficient : cone denstiy
only 35 % of normal,
has only S and L cones.
Rod achromat
Congenital rod
achromat
 1,00 %
 0,02 %
 1,10 %
 0,01 %
 0,002 %
?%
Basic forms of colour deficiency
Protanópia
Deuteranópia
Tritanópia
Ishihara test
8 % of males is colour deficient, in case of females it is only
0,4 %.
With regard to the colour deficient!
Old
coloration
Normal
Deuteranop
Modern
coloration
Thanks for your kind attention!
This publication/research has been supported by the
TÁMOP-4.2.2/B-10/1-2010-0025 project.