So recently I’ve been increasing the size of some of the textures in Black Mesa but when I re-size them they become slightly blurry is there any way to re-size them in gimp with as little loss in quality as possible.
You do understand that resizing them does not increase their quality, right?
If so, I’m afraid I can’t help you; I never managed to figure out that program myself.
I realize that but I’ve done it on the Character faces and they seem to look somewhat better looking in game.
By increasing the resolution of the textures, you’re messing with the scale at which they were applied in the level editor.
The only way to fix it would be to open the maps in Hammer and readjust the scale, but I’m not sure you can do that without the .vmf files.
And, really, there’s only so much information on a texture file, simply increasing the dimensions won’t do much except make it blurrier. If you really want to make the textures themselves higher res, you’ll need to edit the textures to add more detail.
Good luck; I believe that there are thousands of textures in this game.