Apple Aperture 3.5 - Manual (Page 284)

Chapter 7 Make image adjustments 284
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To adjust the tonal curve of an image based on an evaluation of each color channel: Click the Auto
Curves Separate button.
Click the Auto Curves
Separate button to
automatically set
the tonal curve for
the photo based
on an evaluation of
each color channel’s
luminance values.
The tonal curve of the image is adjusted. To fine-tune the tonal curve adjustment, see the
following instructions.
Manually adjust the tonal curve of an image
You use the tonal curve in the Curves adjustment controls to adjust the overall tonality of an
image. There are two types of tonal curve adjustments: RGB and Luminance. When you want
to specify a tonal curve adjustment that modifies both the contrast and the tint in the image,
you use the RGB tonal curve. When you want to adjust the overall tonality of an image without
affecting its color cast, you use the luminance tonal curve.
As you perform a tonal curve adjustment, a histogram appears behind the tonal curve and is
updated as you manipulate the tonal curve. You can specify the tonal range of the histogram to
focus the graph on the part of the tonal curve you plan to work with. For example, if you plan
to manipulate the contrast in the shadow areas of the image, you can limit the tonal range of
the tonal curve and histogram to display pure black to 50 percent gray only. You can also extend
the range of the histogram and tonal curve beyond pure white to capture highlight detail that
would be clipped otherwise.
1 Select a photo.
2 If the Curves controls aren’t shown in the Adjustments inspector or the Adjustments pane of the
Inspector HUD, choose Curves from the Add Adjustment pop-up menu.
Channel pop-up menu
Curves Action
pop-up menu
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