Color Picker Dialog Box
The Color Picker dialog box is available in many areas of Photoshop. The easiest way to get to it is to click your foreground or background color. There are many choices in this dialog box because there are many different ways to define a color. In this section, we'll cover all the various ways you can choose a color. I'll start off by showing you how to preview the color you're selecting.
Previewing a Color
While you're choosing a color, you can glance at the two color swatches to the right of the vertical gradient to compare the color you've chosen (the top swatch) to the color you had previously (the bottom swatch).
Be sure to watch for the out-of-gamut warning, which is indicated by a small triangle that appears ...