Let’s say you’re using the Curves dialog for correcting images and you have an image where you’re trying to adjust the color of some green plants. How do you know where that particular green “lives” on the curve so you can dial in and adjust it? Photoshop can tell you—in fact, you can have Photoshop automatically plot that color on the curve for you. With the Curves dialog open, just Command-click (PC: Control-click) on that color within your image. Photoshop will then add a point to the curve that represents the spot you sampled, and now you’re ready to tweak it.