The Eyedropper tool lets selecting a color from an image. Press I to quickly access this tool.
A color selected with a mouse-click is shown as the current color in the Color palette. If you move a cursor holding down the Eyedropper tool you can see how the current color dynamically changes. Moving the Eyedropper with the pressed Shift-key averages out colors along all pixels in the cursor's path.
Adjust the tool's options in a popup menu which shows when right-clicking on the image or in the Settings Panel.
In the popup menu you can select between the variants. In the Settings Panel it's possible to set more precise Sample Size using the slider or entering a numerical value in the parameter field.
1. Gradient line with the current color in the center, on the left side is +30% black, and on the right side +30% white.
2. The previously selected color.
3. The current color of the pixel where the cursor is.
4. Colors of surrounding pixels.
5. Average colors from areas of 3x3, 5x5, 11x11, 31x31, 51x51, 101x101 px (around the eyedropper's tip).
This feature helps you select colors more precisely. If it's hard to catch a certain color, you can see adjacent tints in the Color Ring and select the color on the ring while holding the Ctrl-key.