What it says on the tin. I'm using 2xBRZ and 4xBRZ filters to upscale vanilla Minecraft blocks/items (because TFC+ still uses those), TFC+ as well as some of the mods that work with it.
- Vanilla Minecraft 1.7.10
- TFC+ 0.82.7
- TFC+ Udary 0.3.01
- TFC+ Cellars Addon 1.1
- Antique Atlas 4.4.4
In order to make full (or likely any) use of these you will have to use Optifine as well as one of SEUS Shaders (SEUS Renewed 1.0.0 tested). Others might work too if they make use of normal/specular maps but you'll have to experiment on your own.
Make sure to go through the shader options and see if there is an option to specify the resolution of your resource pack (2xBRZ is 32, 4x is 64 but I haven't made the specular/normal maps for these yet). These are far from perfect as I'm mostly just experimenting, feel free to give constructive criticism, I know full well myself that these are flawed.
Specular maps make surfaces shiny/metal-like (or at least they're supposed to) and normal maps add the bumps. Here's SEUS' documentation for the way their shaders implement the maps.