Page 117 - Graphic Design and Print Production Fundamentals

Graphic Design 105
spoke of Lab earlier as the three-dimensional model colour science has produced to map the way we
perceive colour. The Lab colour space is device independent because we do not depend on the values
associated with the output of a specific device to enumerate the colour. Lab values are calculated
from spectral readings in a controlled environment so that they define a consistent colour experience
for any circumstance and from any device. Device independent colour is the Rosetta stone of colour
management that allows us to translate from the unique dialect of colour behaviour on one device into
a universal language and then back to the specific colour dialect of a different device and maintain the
colour meaning.

The device independent colour spaces are known as profile connection spaces (PCS) since they provide
this gateway service between the device dependent colour spaces of individual devices. Lab and XYZ
are the two PCS allowed in the ICC specification that defines profile creation. From the examination
of the measurement file, we can see how it provides the first step in establishing and tabulating a
relationship between the device dependent values of a particular device’s output and the corresponding
device independent values that characterize the actual colour appearance associated with the output.

We’ve talked about the measurement file as the gateway to our profile creation, so let’s see what steps
remain to get us there.