chapter 7: editing your shots 179
Contrast
The Contrast slider changes the shape of the histogram by pushing the data out in
both directions. Contrast is the difference between the darkest and lightest tones in
your picture. If you increase the contrast, you “stretch out” the shape of the histo-
gram, creating darker blacks and brighter whites (Figure 7-12). When you decrease
the contrast, youre scrunching the shape of the histogram inward, shortening the
distance between the dark and light endpoints. Since the image data now resides in
the middle area of the graph, the overall tones in the picture are duller. Photographers
might call this look “flat” or muddy.
Contrast works especially well for these “flat” shots because a single slider moves
the histogram in two directions at once (outward toward the edges). You can create
a similar effect in Levels by moving the endpoints inward toward the edges of the
histogram.
Which approach is better? If the histogram data is centered in the middle of the graph,
then Contrast is the easier adjustment because it pushes the data outward evenly. But
if the histogram data is skewed to one side or the other, then Levels is the better choice
because you can adjust the highlights and shadow areas independently.
Highlights and Shadows
These two new sliders are new in iPhoto ’08, and they’re being met with cheers and
ticker-tape parades. They’re designed to recover detail in the highlights and shadows
of your photos, turning what you once might have been unsalvageably overexposed
or underexposed photos into usable shots.
Sure, you can find this kind of sophisticated adjustment in Adobe Camera RAW or
Aperture—but iPhoto?
Suppose you’ve got everything in the photo looking good, except that you don’t have
any detail in either the brightest parts of the shot or in murky dark areas. All you have
to do is drag the appropriate slider and watch as the detail magically appears from
the murk (or the bleached-out brightness). Suddenly, you’ll see texture in what was
once washed-out white walls, or detail in what used to be solid black (Figure 7-13),
or discover that Uncle Bob’s missing black cat was hiding under his chair all along.
You have to be a little careful; if you drag the Shadows slider too far, everything takes
on a strange, radioactive sheen. But used in moderation, these sliders work magic,
especially if you’re working with RAW files.
Color Balance
If all you ever shoot is black-and-white photos, then Levels or Exposure/Contrast
may be all you ever need. If youre like most people, though, you’re also concerned
about a little thing called color.
Contrast
180 iphoto ’08: the missing manual
Truth is, digital cameras (and scanners) don’t always capture color accurately. Digital
photos sometimes have a slightly bluish or greenish tinge, producing dull colors,
lower contrast, and sickly-looking skin tones. In fact, the whole thing might have a
faint green or magenta cast. Or maybe you just want to take color adjustment into
your own hands, not only to get the colors right, but to also create a specific mood.
Maybe you want a snowy landscape to look icy blue, so friends back home realize
just how darned cold it was!
Color Balance
Figure 7-13:
Top: Even though
the histogram
looks good for
this shipwreck
photo—it has a full
range of darks and
lights—there’s a lot
of detail lost in the
shadows.
Bottom: Drag the
Shadows slider to
the right. Presto!
A whole world of
detail emerges
from the murk.
This ship is not
only wrecked, but
rusty and painted
as well. Who
knew?

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