How to calculate FWHM of beam profile

Hi,

I had acquired an image. After that, I plotted a beam profile from that image (as shown in attached picture below). I need to evaluate the FWHM of that beam profile in order to obtain distance between two point at half of maximum value.

The other problem I had faced is the noisy at pixel number 51 - 52.

My idea is to eliminate the noisy pixels and evaluate the FWHM. But, I dont know how to do it since the beam profile was flipped. Anyone know how to do it?

Thank you.

[dpb]

Use negative of signal to turn peak upside down is the classic way...

[Akira Agata]

Using median filter medfilt1 will remove this kind of spike noise. Then, use negative of signal. And applying findpeaks to identify the peak position. I believe this would be a straight-forward way to solve this problem.