filtering noise from image and higlighting tubular structures

Hi, I'm required to highlight the faded- white tube structures (marked several with green circles) in the image below (gray background) and get rid of the black dots (marked with red). Among many things, I tried using "fibermetric" filter and adjusting the contrast (the result is shown in the image with black background) , but for some reason the black dots become highlighted also. How do I approach this kind of problem?

Thanks, Jordan

Answer 1

[Image Analyst]

Try a tophat or bottom hat filter, imtophat() or imbothat().