The colour bar displays the colours that the user picks. The left and right marker text fields below the colour bar displays the grey level values represented by the markers on the colour bar. They can also be used to move these markers to a specific value. These values can also be modified by dragging the markers with the mouse. In the standard mode, the markers are filled with the colours they are pointing to. In custom mode the markers are filled with the choices made for the first and last colours in the interpolation.