How to measure FWHM



I’m using “Plot Profile” and “Curve Fitting” inside Analyze menu to measure FWHM of tubulin in superresolution images. I’ve tried drawing and rotating a rectangle, but the box message “Line or rectangular selection required” appeared. Some publications show the rotated rectangles of the measurement areas which aligns the length of tubulins. I would like to know the accurate method to measure FWHM.

The following photo is a rectangle of the measurement area.



Hello sarochin_s!

Something went wrong with your image upload.

Anyhow, if you are trying to measure a profile perpendicular to a structure, but you want to average over some lenght along that structure, you can use a line profile with a line width higher than 1.
Simply double click on the line tool icon and set some width useful for your application. Draw the line (now thickness shows as a transparency), and just get the profile using plot profile (ctrl K).
The profile you get now averages over the whole width of the line.

Good luck!


Good day,

no doubt a wide line selection, as pointed out by Nico, is the way to go if you need to integrate along the structure.

However, what appears highly problematic is the sample image you’ve posted. It consists of only around 30 gray-values and it is slightly over-exposed.

As such the image is not really suited for reasonable measurements of intensity profiles.

Here’s the image for those who have problems downloading it: