Is there a way to interpolate bump or normal map in cycles (in rendertime)?
The same lofi map connected to diffuse has nice interpolation. It looks like there is no interpolation on Glossy BSDF shader whatsoever. And vice versa, you cant achieve Closest neighbour on diffuse.
If you’re using normal maps be sure to select Non-Color Data from the texture node. If it’s a bump doing that, i suppose it’s pretty low res. Anyways, you can choose different type of interpolations, in the texture Node. Linear/Closest/Smart/Cubic.
Closest is no interpolation (no “blurriness” at all), Linear is the default.