Sample image colors with the Eyedropper tool

The Eyedropper tool can sample colors from anywhere in an image and add them to your Swatches panel.

Select the Eyedropper tool (I) .

Use the Options Bar to customize tool settings, like Sample Size and Sample, to get the effect you want.

Click on the color you want to sample.

The the sampled color will become the foreground color and will be added to your Swatches panel.