I am trying to make a few simple textures for a building that will be in the background of an animation. When rendering the textures side by side, I see a faint line where the texture edges are not black which represent a window frame. I remember that there is a way to make them sharp, but I cannot remember where or how to do this. Is this aliasing, and if so where do I turn off that option for this job?

Thanks
vkirchner