
Camera 77
X
Y
Z
=
a
11
a
12
a
13
a
21
a
22
a
23
a
31
a
32
a
33
R
G
B
= A
R
G
B
. (3.20)
For each different triplet (R, G, B) we could have a different (and optimal)
matrix A, but this would definitely be something very unpractical. A single
colorimetric matrix A to be applied to all (R, G, B) colors can be computed
in the following way [205]:
1. Build a set of n test patches of representative or important colors.
2. Under controlled conditions, with a known illuminant (e.g. D65), mea-
sure the tristimulus values of the patches with a tristimulus colorimeter
obtaining (X
i
, Y
i
, Z
i
), 1 ≤ i ≤ n.
3. Under the same conditions, use the camera to measure the (R, G, B)
values ...