Is it possible to convert precise UV mapped texture details into a precise mask instead of having to imprecisely stencil mask it by hand?

Not as straightforward might be an understatement. I sure hope there is a better way to do this. Cubes have an auto UV map. I added that pattern to the new UV mapped diffuse texture in Gimp. Subdivided enough to have a good amount of detail, then baked the diffuse texture to the vertex colors. In ed…