Systems, methods and apparatus are provided through which in some implementations a graphical object is generated around a mathematical boundary of a region of interest in an image. The graphical object has varying opacity in which a higher opacity in areas of the graphical object in close proximity to the boundary acts as a visual cue to indicate close proximity to the boundary, and lesser opacity in areas of the graphical object of more distant proximity to the boundary acts as a visual cue to indicate distant proximity to the boundary.