Color Management and Why We Need It - Color Management for Photographers - page 12

Fig. 1-4 The eyedropper
tool in Photoshop shows a
value of the yellow square,
R227/G186/B0. Every pixel
in an image may contain a
different value. The
Histogram to the right
shows the distribution of
values in each channel
running from dark to light
(left to right on the
horizontal axis).
can be measured from crest to crest, in nanometers (nm; one billionth
of a meter). Well illustrated in Fig. 1-5, there is a range of frequencies
from approximately 400 nm to 700 nm that is visible to the eye. There
are many other forms of electromagnetic radiation with wavelengths
on either side of this range of visible energy (infrared, microwaves, and
radio on one end the scale, ultraviolet to x-rays and gamma-rays on the
other).
Much of what we know about light, an admittedly critical factor to
seeing color, dates back to good old Isaac Newton and his fondness for