To Use Levels To Correct A Color Cast; About The Curves Dialog Box - Adobe PHOTOSHOP CS2 User Manual

Moving the middle slider adjusts the image gamma
Click OK.
5
You can view the adjusted histogram in the Histogram palette.

To use Levels to correct a color cast

Do one of the following to open the Levels dialog box:
1
• Choose Image > Adjustments > Levels.
(Photoshop) Choose Layer > New Adjustment Layer > Levels. Click OK in the New Layer dialog box.
•
Do one of the following to neutralize a color cast:
2
• Double-click the Set Gray Point Eyedropper tool
Enter the values you want to assign to the neutral gray, and click OK. Then click in a part of the image that should
be neutral gray.
Click Options in the Levels dialog box. Click the Midtones color swatch to display the Adobe Color Picker. Enter
•
the values you want to assign to the neutral gray, and click OK. This method has the advantage of showing you a
preview of the values you're assigning.
In general, assign equal color component values to achieve a neutral gray. For example, assign equal red, green, and
blue values to produce a neutral gray in an RGB image.

About the Curves dialog box

The Curves dialog box, like the Levels dialog box, lets you adjust the entire tonal range of an image. But unlike Levels,
which has only three adjustments (white point, black point, gamma), Curves lets you adjust up to 14 different points
throughout an image's tonal range (from shadows to highlights). You can also use Curves to make precise adjust­
ments to individual color channels in an image. You can save settings made in the Curves dialog box for use in
another image. See "To save and reapply settings in a dialog box" on page 282.
in the Levels dialog box to display the Adobe Color Picker.
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