Improving dpi of a screenshot with a proper scaling of orientation axes

Hello users,
I am trying to generate high-resolution publication-worthy images (600 dpi) out of Paraview. As the first step, I simply increase the resolution of the screenshot of my visualization, which is in pixels. However, this process makes the orientation axes extremely small, almost to the point of making them unreadable. Is there a way around it? Mind you I had already made the axes quite big, almost three times their original size.

Debadutta Prusty