When you generate mattes, modify shots, or match colours between shots, you can sample the current image in the Player. When you sample the image, the input and output colour values are displayed in the Pixel Analyser.
The sample will appear in the Curves menu so you can view input colour values when you refine the image. R, G, and B colour values are plotted separately on the RGB curves while the combined RGB colour value is plotted on the Hue, Saturation, Lightness, and Luminance curves.
When you create a key, you must sample the image to set tolerance and softness values. See Creating a Secondary by Keying a Range of Colours.
The sample appears in the Pixel Analyser.