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ImageJ macro to conveniently (and quickly) change the scale of opened images.
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Quick Set Scale

With this ImageJ macro you can quickly change the scale of an image according to pre-defined parameters, usually based on your equipment.


You must know the pixels/unit ratio for each magnification beforehand, otherwise you cannot use Quick Set Scale. Do not use the default settings, it was calibrated for a specific set of equipments (camera, compound scope, objectives, etc). Using it to set the scale of an image taken with a different setup will give you the wrong measurements.

The ratio is shown whenever you run Analyze > Set Scale.... Take note of it for each magnification you want quick access to and you are ready to go. For example:

Zeiss Axioplan2 with attached Nikon Coolpix at max zoom

Objective       pixel/µm
2.5x            2.0450
10x             0.5277
20x             0.2571
40x             0.1333
100x            0.0525

If you do not know how to calibrate the scale in ImageJ there are plenty of tutorials out there (a good example).


  1. Copy QuickSetScale.txt to ImageJ/macro/toolsets/


Quick Set Scale comes with 2 examples. Simply remove, add, or change the values to fit your parameters. You can add as many setups as you may dare.

Edit the list of setups on this line (newArray items):

Dialog.addChoice("Equipment:", newArray("Microscopio Zeiss Axioplan2", 
"Lupa Zeiss Stemi SV11 APO"));

Input your magnifications and pixel/unit ratios using the template:

if (equip=="Microscopio Zeiss Axioplan2") {
    magnifications = newArray("2.5x", "10x", "20x", "40x", "100x");
    scales = newArray("2.0450",  "0.5277", "0.2571", "0.1333", "0.05255");
    setScale("Zeiss Axioplan2", magnifications, scales);



  1. Restart the program (or launch).
  2. Click on the toolset switcher on right-end of ImageJ's toolbar and select Quick Set Scale.


Originally published at (in Portuguese).

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