3.3

Chapter 17 Making Image Adjustments 350
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Range pop-up menu: Choose a viewing range option from this pop-up menu. Choosing
Shadows restricts the view of the histogram and tonal curve from pure black to 50 percent
gray. Choosing Normal presents the view of the histogram and tonal curve from pure black
to pure white. Choosing Extended enlarges the view of the histogram from pure black to two
times pure white. Because some cameras are capable of capturing image information beyond
pure white, using the Extended range option provides controls for bringing that information
into the viewable image.
Working with the Auto Curves Buttons
You use the Auto Curves buttons to analyze the image and apply a tonal curve adjustment to the
image based on that analysis. This is a good way to make a quick correction to an image before
ne-tuning the Curves adjustment with the manual adjustment controls.
To automatically adjust the tonal curve of an image based on total luminance
When you want to quickly adjust the tonal curve of an image based on total luminance values—
red, green, and blue channels combined—you click the Auto Curves Combined button. Red,
green, and blue channels are adjusted by the same amount based on the total luminance. You
use the Auto Curves Combined button for luminance when you want to correct the contrast of
the image without modifying the color cast of the image.
Before Auto Curves Combined adjustment After Auto Curves Combined adjustment
1 Select a photo.
2 If the Curves controls are not shown in the Adjustments inspector or the Adjustments pane of
the Inspector HUD, choose Curves from the Add Adjustment pop-up menu.
3 In the Curves area of the Adjustments inspector or the Adjustments pane of the Inspector HUD,
click the Auto Curves Combined button.
Click the Auto Curves
Combined button to
automatically set the
tonal curve for the
photo based on all
three color channels.