Digital Prints

color geeky, you’ll want to explore the
concept of E, spoken as Delta-E, where
each E unit represents the just-noticeable
difference between any two LAB colors.)
The LAB color space most closely represents
how humans see. It’s the one that
Photoshop uses for its mode changes. It’s
the one that color management systems
(see below) generally use as a reference
space to relate their input and output
behaviors. It’s the largest of all the common
color spaces, and it includes most of
the colors in the RGB and CMYK
gamuts. Best of all, LAB is not dependent
on any particular device, ink, or process.
It just is, offering universal color definitions.
Admittedly, it’s a little
hard to understand LAB,
which is why you may not
be spending much time
there except for some specialized
purposes.
RGB
RGB is the dominant
color space for digital
artists. It’s based not only
on the viewable colors on
a television screen or
computer monitor, but
also on the fact that red,
green, and blue form the
basis of the tristimulas
model of color perception, which scientists have now discovered corresponds to how our
nervous systems perceive color.
RGB is the default space for most digital cameras and scanners (all scanners scan in RGB;
if you’re getting CMYK scans, the scanner operator or the software is converting the data),
and it’s the preferred space for film recorders, digital photo print, and most desktop inkjets.
That last one may surprise you, but even though inkjets must print real inks on real paper
in CMYK fashion, they prefer RGB files, and some people actually call them “RGB
devices.” I wouldn’t go that far, but it is true that Epson printers, for example, are RGBbased,
and if you send CMYK information to an Epson through its normal printer driver,
it will first convert the data to RGB and then back again to CMYK for printing! (The use
of a CMYK RIP will bypass this workflow.)
Chapter 4 ■ Understanding and Managing Color 121
Figure 4.5 The CIE xyY
Chromaticity Diagram, which
represents (in two dimensions) the
color range of human vision.
Graphing by CHROMiX ColorThink
Figure 4.6 The three-dimensional
ICC LAB color space.