Technical information

48
8
.2
C
olour renderin
g
C
olour is a sensor
y
impression conve
y
ed b
y
the e
y
e.
The evaluation o
f
a colour stimulus b
y
the e
y
e causes
a uniform effect (colour stimulus specification). This
can be described by colourimetric numbers
(
e.
g
. x,
y
and z in the
C
IE 1931 or
C
IE 1976 colour space or
L, a and b in the
C
IE 1976
(
L*a*b*
)
s
p
ace or W, U and
V
in the
C
IE 1964 colour s
p
ace
(
W*, U*, V*
))
. But the
p
erceived colour
(
the sub
j
ective im
p
ression
)
de
p
ends
on the general conditions
(
colour mood, surrounding
surfaces, luminance
).
Th
e pr
i
mar
y
co
l
ours,
i
.e. saturate
d
monoc
h
romat
i
c co-
lours, run around the periphery o
f
the colour trian
g
le
.
A
n ideal black bod
y
(
or Planck radiator
)
radiates an
e
l
ectroma
g
net
i
c spectrum
d
epen
di
n
g
on
i
ts tempera-
ture.
Th
e co
l
our t
h
us
d
epen
di
n
g
on temperature
i
s
d
e
pi
cte
d
i
n t
h
e
Pl
anc
k
curve, t
hi
s
i
s t
h
e so-ca
ll
e
d
“colour tem
p
erature”
.
C
olours on the Planck curve are marked with the
corresponding colour temperature; chromaticity coor-
dinates deviating only slightly
f
rom the Planck curve
(
within the ran
g
e of the Judd strai
g
ht lines, corre-
spondin
g
to a distance o
f
approx. 5.4 threshold
v
alue units) are marked with the correlated colour
tem
p
erature.
Fi
g
. 50:
S
tandard colour chart as per DIN 5033
Fi
g
. 51: Definin
g
the colour renderin
g
indices in comparison for two li
g
ht sources
O
ne way of showing the colour impression is the stan-
d
ar
d
c
h
art as per
DIN
5033 –
b
as
i
c st
i
mu
l
us
.
Reference color temperature 4000K
HQL-Standard
HCI - NDL
R
1
: 99
R
2
: 97
R
3
: 88
R
4
: 96
R
5
: 97
CRI: 95
R
6
: 95
R
7
: 96
R
8
: 93
R
1
: 46
R
2
: 61
R
3
: 54
R
4
: 46
R
5
: 43
R
6
: 36
R
7
: 66
R
8
: 44
CRI: 50