Margulis - Photoshop LAB Color

Margulis - Photoshop LAB Color, INNE - RÓŻNOŚCI, Photography

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A
B
 The Canyon Conundrum
LAB
has a reputation for enormous power, yet virtually all reference
materials that advocate its use illustrate its capabilities with a single
class of image. This chapter introduces the basic
LAB
correction method
and explains why it is so extraordinarily effective—if you happen to
have a picture of a canyon.
eep in Death Valley, land of desolation and summertime heat
in the high 120s, a narrow canyon holds several lessons
about color, photography, human perception, and a power-
ful digital imaging tool.
Parts of the clayish soil contain mineral deposits that
create striking color variations, especially when the light
hits just right in the late afternoon. The effect allegedly reminds some
people of a painter mixing up the tools of his trade.
So, it’s called “Artist’s Palette,” a considerable stretch. These dull tints
have about as much to do with those found on the palettes of Renoir or
Rembrandt as this book does with animal husbandry. But nothing seems
great or small except by comparison. It’s such a shock to encounter green
or magenta dirt that it seems absolutely blazing next to the monotony
of the surroundings. People stand and stare at Artist’s Palette for hours,
seeing subtleties that cameras can’t record and imagining brilliant colors
that cameras don’t think are there.
We can leave aside the philosophical question of whether the reality is
these dull colors that the camera saw in Figure 1.1A, or the comparatively
bright ones conjured up by the infinitely creative human visual system.
The fact is, if this picture is a promotional shot or even something for a
nature publication, the original isn’t going to fly. Anybody would prefer
Figure 1.1B, which was created in approximately 30 seconds in
LAB
.
When I first wrote about
LAB
, in a 1996 column, I used a canyon shot
Figure 1.1
This Death Valley canyon is noted for its strangely colored clay. Green soil like that on
the right side of this photograph is so unusual that people remember it as being greener than what
the camera saw. Canyon images are often used to illustrate the power of
LAB
correction (bottom).
1
 4
Chapter 1
from Capitol Reef National Park in Utah. My
book
Professional Photoshop
goes around 100
miles to the south with a shot from Canyon-
lands National Park.
Another Photoshop book illustrates its
LAB
section with a shot from Bryce Canyon Na-
tional Park. A third uses a scene from Grand
Canyon National Park, and a fourth a canyon
from the Canadian Rockies. And author Lee
Varis has a scintillating
LAB
exercise, repro-
duced here in Chapter 16, that brings out the
best in a canyon in North Coyote Buttes, on
the Arizona/Utah border.
Start to detect a pattern?
Ye s , in d e e d .
LAB
does really, really well
with canyons. And you don’t even need to
know how it works to make the magic hap-
pen; the approach to canyons is simplicity
itself. Figure 1.1B isn’t the best we can do in
LAB
(we’ll be revisiting this image in Chapter
4, treating it in a slightly more complex way)
but it’s much better than any comparable
moves in
RGB
or
CMYK
, and even if you could
match the quality in some other colorspace it
would take far longer.
When I wheeled out that first canyon shot
in 1996, I likened
LAB
to a wild animal: very
powerful, very dangerous. That label has
stuck. Use of
LAB
is now widespread among
top retouchers, but a huge fear factor limits
the techniques they use it for. Most of those
who claim to be
LAB
users are only doing
what’s described in the first five chapters
here, missing out on much magic.
You c a n’t bl a m e t h e m f or b e i n g s a t i s fi e d
with what they’ve got, because those limited
LAB
tools can make an extraordinary differ-
ence in image quality. They are also so simple
that beginners can enjoy their benefits.
I hope, and the publisher hopes harder,
that people with limited experience will
learn enough to dramatically improve their
pictures. On the other hand, some of what
follows either is unbearably complicated or
suggests methods that only power users can
fully appreciate. For the best of reasons, it
isn’t customary for Photoshop books to cater
to novices and simultaneously include mate-
rial that leaves experts cursing in frustration
until they re-read it for the eighth time.
Special handling is clearly required.
The Rules of the Game
Each of the first six chapters is divided into
two parts, readily identifiable by a change
in typeface. If you’re just trying to get into
working with
LAB
as quickly as possible, you
can skip the second part of each chapter,
which is more analytical, and can be some-
what difficult to follow.
Figure 1.2
Like Figure 1.1, this image features colors
that are possibly accurate, yet too subdued when taken
in the context of the scene. This canyon is called
“Yellowstone” for a reason. The yellowness of the
canyon walls should be played up.
 The Canyon Conundrum
5
For efficiency’s sake we will bypass two
customary procedures. First, a few para-
graphs ago, I did something that I find
exceedingly irritating when other authors try
it. I asserted that a certain way of doing things
is better than the customary alternative, and
expected you to take it on faith. Yet, if I
had stopped to prove that straight
LAB
correction indeed yields better results than
RGB
in canyon images, there would have
been an eight-page detour.
So, in the interest of speed, the first half of
each chapter concentrates on the how, not
the why. I will say things that might be
labeled matters of opinion without stopping
to prove they are so. Take my word for them if
you like; if you’d rather not, they are backed
up in the “Closer Look” section.
Also, the first halves don’t assume much
Photoshop expertise. I try to give simple
explanations of each command being used.
The second parts play by no such rules, and
often dive right into techniques familiar only
to a sophisticated audience. And they don’t
offer many explanations of Photoshop basics.
LAB
is always an intermediate step. Files
must be converted into it before the fun
begins and out of it afterward. Almost every-
one will be converting into
LAB
from an
RGB
file. When finished, some will convert
back to
RGB
and others, needing a print file,
will go to
CMYK
. For the time being, it doesn’t
matter which; we will assume for conve-
nience that it goes back to
RGB
.Your defini-
tions of
RGB
and
CMYK
in Photoshop’s Color
Settings dialog don’t matter yet, either. We’re
now ready to tackle some canyons.
designed not just to encompass all conceiv-
able colors (and some that are imaginary, a
fascinating concept that we’ll explore at
length later, notably in Chapter 8), but to sort
them out in a way that relates to how humans
see them.
The version of
LAB
used in Photoshop was
born in 1976, child of a standards-setting
group called the International Commission
on Lighting and known by its French ini-
tials,
CIE
.
There have been several close relatives.
We need know nothing about them, but color
scientists feel that we should use a more
precise name for our version. They call it
CIELAB
or L*a*b*, both of which are a pain to
pronounce and maddening typographically.
Photoshop calls it “Lab color,” but the name
has nothing to do with a laboratory: the
L
stands for luminosity or lightness; the
A
and
A 30-Second Definition of
LAB
It would take a wheelbarrow to carry every
way of defining color that’s been propounded
in the last century. Our current
LAB
is one of
the most prominent, an academic construct
Figure 1.3
A more vivid version of Figure 1.2, prepared
using the
LAB
recipe of this chapter.
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