Operation Manual

Points on the curve that are not selected remain anchored, allowing you to independently
adjust each tonal area.
Darkening the shadows
and lightening the
highlights creates
an S-curve, indicating that
the image’s contrast
is increased.
9 Repeat steps 7 and 8 for each tonal area in the image that you want to correct.
The tonal values in the image are adjusted, giving the image the appropriate amount of
contrast.
Using Eyedropper Tools to Set Black, Gray, and White Points
You use the Black Point, Gray Point, and White Point eyedropper tools in the Curves
adjustment controls when you want to have Aperture selectively modify the tonal values
of the shadows, midtones, and highlights in an image automatically. Using an eyedropper
tool, you sample the pixels of the tonal value in the image you intend to correct, and
Aperture places a point on the tonal curve and automatically adjusts the image so that
the pixels that fall in the same tonal range as the sampled pixels are set to either black,
gray, or white. For example, you use the Black Point eyedropper tool to select the specific
area of the image that should be black. Aperture samples the pixels within the selection,
places a point on the curve, and then adjusts the curve to make the selected pixels—and
all other pixels in the image of the same tonal value or darker—black.
In some difficult cases, you can use the Black Point, Gray Point, and White Point eyedropper
tools in combination with points that you manually place on the tonal curve to neutralize
a tint or create the specific contrast you want in the image. For more information about
manually adjusting the tonal curve, see Adjusting the Tonal Curve of an Image Using the
Curves Controls.
546 Chapter 17 Making Image Adjustments