From VFXPedia

Status Bar Information

The status bar at the bottom of the Fusion interface will provide the exact RGBA and Z values for the pixel beneath the mouse pointer if the mouse is over one of the display views. Additional information about the X and Y coordinates of the mouse and the exact pixel position are also displayed in the status bar.

The Color Inspector subview can also be used to show more information about the pixels in the view.

See Subviews earlier in this chapter for more details.