How to Calibrate
Calibration refers to the process of determining the relation between the
output (or response) of a measuring instrument to the value of the input
quantity or attribute, a measurement standard. In non-specialized use,
calibration is often regarded as including the process of adjusting the
output or indication on a measurement instrument to agree with value of the
applied standard, within a specified accuracy.
To set calibration, use the Set Viewer Calibration button
located on the Viewer Control Toolbar.

Left Click selects the next available calibration
Right Click bring up a selection menu
Select Show and the distance line will be displayed in the image viewer. Adjust this on a know distance. Once you have placed the distance line where you want it, right-click the Calibration button again and select Set
The edit box will appear. This is where you set the calibration distance. Enter your
value, click Apply and then Close.
Reset will reset the calibration to pixels.
To test from the Viewer Control Toolbar select the Measure Distance Tool
from the Measurement Toolbar.
Pick
on the two points that you used to set your calibration and the
measurement distance will be shown using the new calibration value:
Calibration using the measurement tool
You can also set the calibration by using the Measure Distance Tool.
First reset the calibration of interest. Use Measure Distance Tool and once you have defined the distance measurement, right click the calibraiton tool and choose Set
Enter your distance value, click Apply then Close.
If you have more the one measurement distance on the viewer the selected/highlighted one will be chosen