Insert a Ruler to Measure Distance on an Image

Insert a ruler on an image to measure the distance between a starting and ending point.

Select an image.
Select the Line Style button and set up the style of the ruler tool.
Select the Ruler button.
Select to select the starting point on the image.
Drag the line to the end point, and then release the mouse button.
The Ruler Calibration window opens and displays measurement information that corresponds to the ruler.
In the Unit list, select a unit of measure.
Set a number of Decimal Places for the measured length.
To use the resolution information stored in the image file to calculate the measured length if you resize the ruler and automatically recalculate, clear the Measurement check box.
If you choose a different unit of measure, the measurement updates automatically.
To calculate measurements based on information you provide to calculate the measured length, select the Measurement check box and enter a new ruler length.
If you choose a different unit of measure, the measurement does not update automatically. If the Measurement check box is selected, the Recalculate on resize check box must be selected.
To enter a value that does not change when the ruler is resized, select the Measurement check box, and then clear the Recalculate on resize check box.
The measurement does not update automatically.
Select the Select button and right-click the measurement and select Properties.
The Properties window opens.
To save the image with the ruler, select Save.