Graphics Programs Reference
In-Depth Information
this document, it will preview correctly, but I can't be sure that when R
= G = B this will produce a neutral. This document is still considered to
be in an RGB working space. That is, any RGB document we open in
Photoshop, whether it is well behaved or directly from a capture or
output device, is considered by Photoshop to be in an RGB working space.
Therefore, it is important to differentiate the differences between RGB
working spaces based upon these synthetic constructs and RGB working
spaces based upon some actual device.
Two primary attributes of these synthetic RGB working spaces sepa-
rate them from one another. The most important is the color gamut of
the working space. As we will see, these working spaces range from a
rather small color gamut to working spaces that have a very large color
gamut. The other attribute is the gamma encoding of the working space.
This gamma has nothing to do with the gamma of your display, but rather
the gamma (TRC or tone corrections) of edits that are applied to the
image. A 2.2 gamma encoding of a working space is somewhat prefer-
able since the edits applied over the tone curve are more evenly spaced
and approximately perceptually uniform. What this means is that if you
apply an edit to a document in Photoshop, the visual change from one
level to the next level over the tonal range appears the same. Even if the
working space isn't perceptually uniform, Photoshop does a very good
job, thanks to the Display Using Monitor Compensation of showing you
the relative strengths of an edit applied over the entire tone curve of the
image.
There are a number of RGB working spaces that were created for this
well-behaved editing behavior of our images. Over the years, some have
undergone name changes, some have been removed from installation by
Adobe Photoshop, and some have been created by users and color geeks
to be loaded into Photoshop. Before we look at the more common RGB
working spaces and what differentiates them, it is important to under-
stand there is no perfect RGB working space. If there were, we'd need to
use only one! When Adobe decided to implement RGB working spaces
in Photoshop, they understood this, and provided a number of choices—
some would say, too many choices. Some RGB working spaces are ideal
for certain users and not for others. After a description of some of the
available working spaces and a tutorial, you should have a much better
idea of what these RGB working spaces can provide. See Chapter 9, Tuto-
rial #4: “RGB Working Space.”
Which Working Space?
Think of the various RGB working spaces as standard editing spaces.
Many of the working spaces Adobe implemented are based on RGB color
spaces that have been used in various industries for years. These
Photoshop-provided RGB working spaces have an increasingly wider
color gamut: from sRGB, the smallest to Wide Gamut RGB, and beyond.
