How incident rays refracted by a convex lens?

By convex lens, rays fallen would be definitely converged hence named as converging lens. If rays fall parallel to the principal axis after refraction they would be converged at a point known to be the principal focus of the lens. If rays go in diverging state as the source is in between its F and O, optic centre then they would appear to come from the same side and so we get a virtual enlarged image. This is what a palmologist does with a lens to read the lines on the palm. Optic centre is the point on the lens through which as rays pass then it goes unrefracted or undeviated.