Absolute Beginner's Guide to Digital Photography

CHAPTER 15 THE IMPORTANCE OF LEVELS AND CURVES 227

FIGURE 15.10
The classic S
curve that is
often used as a
gauge to
increasing
brightness and
contrast in an
image.

Understanding the Curves Dialog Box

The Curves command changes brightness, contrast, and color balance more power-

fully than the Levels and Color Balance commands. Levels enable you to adjust only

three points on the tonal scale: black, middle-gray, and white; Curves lets you adjust

as many as 16 gray points, more than most images need. In addition to a curve for

the combined colors, there is a curve for each primary color. Thus Curves will do

what the Color Balance command does, and do it with more power and control.

The straight line from the bottom-left corner of the graph to the top-right corner is

what will become a “curve.” When you click and drag on the line, it becomes elastic

and forms a curve (see Figure 15.11). Moving this line changes the tones of the

image.

FIGURE 15.11
The curve
becomes an
elastic curve
when you click
on it and drag
with the mouse.