I have scanning electron microscopy image for a steel sample and I want to measure its surface roughness by applying that image into ImageJ software application
Ganesha Krishna V S Unfortunatly "method" in a link you gave us is highly misleading. I am not aware about any ImageJ plugins capable of roughness measurements. There are software packages capable of full 3D reconstruction from SEM pictures, including roughness measurements, but they are not cheap.
@vladimir, as I have tried both Imagej and AFM, I am aware of the method and its realiability. So I said go for AFM. However, using imagej is given in the link is the way to do it with imagej.