User`s manual

Reference: The Preview Window 47
Choosing the White & Black Points of an image
There are two ways to choose the white and black points of an image:
A. By using the Tag Windows tool in the Toolbar.
1) To choose the highlight (white) point in an image, click the Tag
Windows tool, press the Apple Command key, and click on a white
point in the image.
2) To choose the shadow (black) point in an image, click the Tag
Windows tool, press the Option key, and click on a black point in the
image.
B. By using the Magic Diamonds. See the next section for details.
Tag Windows tool
Magic Diamonds