Mesh rendered material and Render Software

Aaaaarghh you contradict yourself. But whatever, I think if there are different color on vertex rendering tools are doing linear interpolation so increasing resolution of texture will not help (as you will surely do linear interpolation). But increasing mesh resolution will.

I have some tool in Nautilus that smooth values on mesh they could be applied on color so with “bad” data you can have a better render. It is a Catmull & Clark tool for mesh and weight on vertex.