Color Sampler Tool
Use the Color Sampler Tool to select a color directly from the surface of your picture, rather than from the palette. This feature is particularly handy when working with 16-million color, 256 color or gray scale images where it can be difficult to distinguish between individual shades or when you want to match a color exactly.
To use the Color Sampler, place the mouse cursor directly over the desired color in your picture. You should be able to spot the color at the center of the cursor's cross hairs. If needed you can use the Zoom Tool to increase the magnification which will make the pixels easier to see. The color you choose will become the selected color in the Color Box. Press the left mouse button to choose a new left/fill color or the right to choose a new right/line color.
The Color Sampler also can be temporarily activated when using other tools by pressing and holding down the CTRL key.