Perfecting Brightness with Curves

Perfecting Brightness with Curves

Curves rocks. I heart Curves. The Curves control is particularly
useful for gamma correction, because
. Curves lets you fully (and visually) control how adjustments
are weighted and roll off.
. You can introduce multiple gamma adjustments to a
single image or restrict the gamma adjustment to just
one part of the image’s dynamic range.
. Some adjustments can be nailed with a single wellplaced
point in Curves, in cases where the equivalent
adjustment with Levels might require coordination of
three separate controls.
It’s also worth understanding Curves controls because they
are a common shorthand for how digital color adjustments
are depicted; the Curves interface recurs in many—most—
color correction toolsets.
Curves does, however, have drawbacks, compared with
Levels:
. It’s not immediately intuitive, it can easily yield hideous
results if you don’t know what you’re doing, and there
are plenty of artists who aren’t comfortable with it.

. Unlike Photoshop, After Effects doesn’t offer numerical
values corresponding to curve points, making it a
purely visual control that can be hard to standardize.
. Without a histogram, you may miss obvious clues about
the image (making Levels more suitable for learners).
The most daunting thing about Curves is clearly its interface,
a simple grid with a diagonal line extending from
lower left to upper right. There is a Channel selector at the
top, set by default to RGB as in Levels, and there are some
optional extra controls on the right to help you draw, save,
and retrieve custom curves. To the novice, the arbitrary
map is an unintuitive abstraction that you can easily use
to make a complete mess of your image. Once you understand
it, however, you can see it as an elegantly simple
description of how image adjustment works. You’ll fi nd the
equivalent Curves graph to the Levels corrections on the
book’s disc.