Color models are based on color mixtures. For example, RGB is the color scheme for digital graphics; CMYK is used for four-color process printing; and HSB represents the human perception of color. Color models like these describe the colors used in digital graphics by using numeral values to represent the colors. When working with colors in a digital image, it is actually the numerical values of the color that are adjusted.
Choose the “Eyedropper” tool in the "Tools" panel, and then select a particular color in your digital image. This will become your new fill or stroke color at the bottom of the "Tools" panel or on the left of the "Color" panel.
Double-click the fill or stroke color at the bottom of the "Tools" panel or on the left of the "Color" panel to open the "Color Picker." The "Color Picker" dialog box contains the "Color Field," the" Color Spectrum" bar, a rectangular area that shows both the original (bottom rectangle) and new (top rectangle) colors, as well as the "Color Model" color values of a selected color.
The "Color Model" options in the "Color Picker" dialog box show you the HSB, RGB, CMYK or hexadecimal numerical values of the selected color.