Brightness, Contrast, and levels
When it comes to luminosity—that is, light colors
compared with dark ones—you most often hear
this expressed as “brightness and contrast,” where
brightness is the lightness or darkness of a group
of colors and contrast is the degree of difference
between light and dark colors, as illustrated in
Figure 6-6. These are the exact qualities that allow
us to distinguish a strawberry from, say, its leaves
or a bowl of inedible unstrawberry-shaped rocks.
Photoshop pays lip service to this colloquialism
with its Brightness/Contrast command. Although
exceedingly easy to use—and vastly improved in
recent years—it lacks the control of Photoshop’s
more capable functions such as Levels, Curves, and
Shadows/Highlights, some of which we’ve used
cursorily in previous lessons. These tools analyze
an image according to three basic attributes—
highlights, shadows, and midtones, or what the
uninitiated might call light colors, dark colors,
and everything in between. But we know better
(having read the last section): We’re talking about
brightness values rather than hue or saturation.
Figure 6-7 provides some examples.PeaRl Of WISDOm
There is no specific, numerical distinction for highlights,
shadows, and midtones. The highlights are the brightest
values in an image, the shadows are the darkest, and the
midtones are the areas in between.Such distinctions not only let you adjust brightness
and contrast but also provide you with selective
control over an image. You can make the shadows
darker, make the midtones lighter, and leave the
highlights unchanged. And you can make these
changes without upsetting the color balance one
iota; or you can adjust luminosity and color val-
ues together. Be it red or blue, night or day, the
sky’s the limit. The later exercises in this lesson
will help you learn how to use these tonal tools to
their best effect.Figure 6-6.Figure 6-7.
Low contrastHigh contrastLow brightnessHigh brightness182 Lesson 6: Adjusting Color and Luminance