Apple Aperture 2 - Manual (Page 370)

370 Part III Performing Image Adjustments
Using the Auto Levels Separate Button
When you want to automatically adjust the levels of an image based on individual
evaluations of the red, green, and blue channels, you use the Auto Levels Separate
button. Red, green, and blue channels are adjusted based on the evaluation of each
channel. You use the Auto Levels Separate button when you want to correct the color
cast in the image in addition to correcting the contrast.
To automatically adjust the levels based on an evaluation of each color channel:
1 Select an image.
2 In either the Adjustments inspector or the Adjustments pane of the Inspector HUD, click
the Auto Levels Separate button.
The levels of the image are automatically adjusted for each color channel. To fine-tune
the levels adjustment, see “
Working with the Levels Controls ” on page 429.
Before Auto Levels Separate
adjustment After Auto Levels Separate
adjustment
Click the Auto Levels
Separate button to
automatically set the
levels for the image
based on an evaluation
of each color channel’s
luminance values.