48-11Colorimetry
to the bidirectional geometries. For semigloss samples, the problem becomes more complex. e two
bi
directional
ge
ometries
ar
e
sim
ilar
to th
e
wa
y
a pe
rson
ev
aluates
co
lor
vi
sually
an
d
ar
e
o
en
th
ought
to ag
ree
be
tter
wi
th
vi
sual
ev
aluation
. On th
e
ot
her
ha
nd,
th
e
di
use
ge
ometries
me
asured
wi
th
th
e
sp
ecular
re
ection
in
cluded
mi
nimize
th
e
e
ect
of th
e
sa
mple’s
te
xture
an
d
gl
oss
an
d
ar
e
qu
ite
us
eful
fo
r
co
mputerized
co
lor
ma
tching
. Ra
ther
th
an
pu
rchasing
mu
ltiple
in
struments,
mo
st
us
ers
se
lect
th
e
ge
ometry
m
ost
s
uited
to t
heir
m
ajor
n
eeds
a
nd
c
ompromise
o
n
o
ther
m
easurements
.
48.5.6 Spectrophotometers
Spectrophotometers are used to measure an object’s reection characteristics throughout the visible
sp
ectrum
. Do
uble-beam
sp