#
 IMAGE menu:
 There are two submenus: BLOCK SELECT; MEASURE DISTANCE.
     
 BLOCK SELECT submenu:
      After mouse-clicking the BLOCK SELECT submenu, the system
 is activated for selecting a rectangular block on the screen.
 The user should place the mouse-pointer on the upper-left
 corner of the desired particle, and push the left mouse-button.
 The user should then drag the mouse-point to the lower-right corner
 of the desired select-block, and release the left mouse-button.
 The SELECT-BLOCK outline appears in red, and the system determines
 the edge of the particle in the center of the SELECT-BLOCK.
 Select EDGE to modify the edge-detection parameters.
     
 MEASURE DISTANCE submenu:
     After mouse-clicking the MEASURE DISTANCE submenu, the system
 is activated for measuring any segment-distance on the screen.
 The user should place the mouse-pointer on the left point of
 the desired segment, and push the left mouse-button.  The user
 should then drag the mouse-point to the right point of the desired
 segment, and release the left mouse-button.  The system provides
 the x-distance (horizontal), y-distance (vertical),
 and the Euclidean distance for the segment.
#