Calibrating the Ruler

Introduction

When a measurement is not available, the ruler displays the value expressed as "--" followed by mm (millimeter), in (inches), or cm (centimeters). Use an object of known length as a reference to calibrate the ruler.

If you know the scale factor that takes the acquired image magnification factor into consideration, enter this value to calibrate your ruler.

Note:

Manual calibration does not apply to volumetric annotations such as 3D sphere. Manual calibration is only available for the ruler.

Steps

1. Measure an object of known length with a ruler.
2. Right-click the Ruler annotation and select Calibrate. Synapse displays the Calibrate dialog box.
3. Do one of the following:

   If you want to ...	Do this ...
   Change the Known Length Scale Factor.	Enter a different value for Scale Factor.
   Enter the Known Length.	Enter the length of the ruler in Known Length. Option: Select Propagate to apply the Known Length value to all images in a series. Note: Calibration propagation is not available for some series and therefore, you could see differences between 2D/3D and the other images in a series. In this case, the Propagate option is grayed out.
   Remove the applied calibration and reset the Scale Factor back to the default value.	Delete the Scale Factor value.

4. Click OK.

Results

Synapse displays an asterisk * next to an annotation value to indicate it was manually calibrated or if the accuracy of the pixel spacing is not guaranteed (ERMF).

Related Topics

Using the Ruler