To measure distance:

1. Open an image in the Image window.

2. From the Image window menu, click Tools | Measuring Distances.

3. In the Measure Method option list, select the measurement method.

4. In the Units options list, select the appropriate unit of measurement.

5. Use the mouse to select points in the Image window.

   The distance between the points and the coordinates of the points are displayed at the bottom of the Measure Distances window.
    

6. If you are using the Multiple Segment method, click Get Distance to display the total length of all of the segments.