You can choose between several different basic units for the active image. Meter, Inch and Angstrom are available.
For example, select the Image > Change Basic Unit > Inch to use Inch as the basic unit for the active image.
Where does the basic unit have an effect on something?
Image calibration
All of the calibration data will be recalculated to the new basic unit.
For example: The active image has been calibrated in the basic unit Meter. One of the active image's pixels is 1 x 1 µm² in size.
Select Inch as the basic unit. The size of the pixel will now be given as 39.37 x 39.37 µin².
Scale bar
The scale bar's unit is the basic unit. When you select another basic unit, the scale bar's labeling will also be changed. The scale bar's length will also be adapted.
Measurement values
All measurement results will be specified in the image's basic unit. Should measurements already have been made on the image, the existing measurement values will be recalculated in the new basic unit.
Changing the basic unit for the image acquisition
The Change Basic Unit command only has an effect on the active image. The basic unit for all of the other loaded images will remain unchanged.
If you want to measure all of your images in the basic unit Inch for example, you can change the basic unit for the image acquisition. You specify the basic unit for the image acquisition in the camera settings, in the Acquisition Settings > Acquisition > General dialog box. For example, in the Camera Control tool window, click the Acquisition Settings 
button to open this dialog box.
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