Question about working on textures in software like Photoshop or Gimp

Hi folks, I’m learning apply textures in Gimp for my models. I made them in Blender. So i’m wandering how can I use a black mask to cover the empty area of my UV layout, but only show the texture that are overlapped with the UVs. (Sorry for my bad English, the screenshot can explain what I want to do) This method seems like the correct way to apply texture to the UVs, I also want to ask if I do it this way, can I still tile it inside of UE4 without making the black area to appear on my model?

You cant really tile a texture like this. for that, you’d need a seamless texture.
You could however multiply (or lerp) this texture with a seamless one for some more variation, but you’ll get seams along the edges of your uv island.

I see. So without worrying about tiling, how can I create a texture like the screenshot shows?

Hmm, either use a 3d program to render out a uv-map and paint over it in photoshop/inkscape, or use something like substance, 3d coat or quixel to make one.