ImageJ scale bar

This page shows you how to add a scale bar to images in ImageJ

Note: in ImageJ addind a scale bar burns that scale bar into the image, so it should be the very last thing you do to the image before presenting it. You should always make a duplicate of you image and add the scale bar to that, so you don't destroy the original image when you save it.

• First you need to set the pixel size in your images, so ImageJ know how many pixels cover, for instance, 1 micrometer.

• If you used Bio-Formats or one of the other plugins or native microscopy formats readers, then imageJ may already know the pixel sizes, and will display them in the top bar of the image window, as a measurement in some unit length instead of just "pixels"

• If this is not the case, you need to tell ImageJ how big each pixel is in x and y dimensions. Use the built in function from the menu: Analyze - Set Scale. Here you can tell ImageJ how many pixels per micrometer, or vice versa. Check or uncheck the 'Global" box to change all open images, or just the active image.

• Next, use the built in function at: Analyse - Tools - Scale Bar. Here you can set the font size, colour, location, size etc. of your scale bar.