The Eyedropper tool makes it easy to copy a color without having to select a swatch. It copies, or samples, the color of an area in your photo to set a new foreground or background color. You can sample from the active image, from another open image, or from your computer’s desktop.
If you want the color always to be available, you can add the sampled color to the Color Swatches palette. You can also specify the size of the area that the Eyedropper tool samples. For example, you can set the eyedropper to sample the average color values of a 5‑by‑5- or 3‑by‑3-pixel area under the pointer.
Point Sample to get the precise value of the pixel you click.
3 By 3 Average or 5 By 5 Average to get the average value of the specified number of pixels within the area you click.
To select a new foreground color from an image, click the desired color in your image. To select a color that appears elsewhere on your computer screen, click inside your image and drag away from it.
To select a new background color from an image, Alt-click the color you want.
As you click and drag the Eyedropper tool, the foreground color box changes.