The Eyedropper Tool is a great way to
sample colors from anywhere in an image
and add them to your Swatches panel.
To use it, first select the Eyedropper tool
from the toolbar. Then, in the Options Bar,
you can customize tool settings like Sample
Size and Sample to get the effect you want.
Finally, click on the color you want to
sample. When you’re finished, the color will
be added to your Swatches panel!