So I have previously set the scale, etc. for some data analysis so that my scale bar would be in microns and not pixels. Unfortunately, when I have tried to do that recently it won’t let me change the units for the scale. Any help?
Can you give us a bit more information? How exactly are you setting your scale - with Set Scale? What version of ImageJ/Fiji/Java are you running? For this info - just click on the status bar and report back.
The more info/details you can give us - the better we can help you.
Like @etarena says, give more information. In particular:
Did you first select a known distance in the image using the line (5th tool), then in the Analyse>Set Scale menu enter the known length (the measured distance in pixels should be filled out automatically), and then enter the units (eg. µm), then press OK? If you change the number in the box of Known distance, does the number after Scale: in the lower part of the Set Scale dialog change? Does it reflect the Unit of Length? Can you enter text in the Unit of length text box at all?
Reason for asking is your use of the sentence ‘my scale bar’, which to my knowledge is not a part of ImageJ (although it can be drawn onto an image with a calibrated image, using the line or rectangle tool). Or do you try to alter ‘Scale Bar’ in the Analyze>Tools menu?