Color sampler tool
From The Glossary of Digital Photography
A software tool built in to Photoshop that allows the photographer to determine the numerical values of discreet color points in an image. It can be set to read color values from a single pixel or from an average of several larger areas. The reading is displayed in 8-bit RGB (red, green, blue), with 0 to 255 for each of the three colors, or in CMYK with the values in percentage. If the image is in 16-bit mode, it still gives a reading of 0 to 255 for each color. The color sampler tool allows the photographer to take four separate readings and display them all as a continuous reading by moving the cursor over the image. The color sampler tool is available in Photoshop by clicking on the eyedropper tool, then selecting color sampler tool from the drop-down menu that appears. The color that is sampled can then be used by the other tools in Photoshop, such as the painting tool or fill tool.
