I've been tinkering a little more with the lighting code, as well as the textures. It is starting to look rather good:
There's a trick to that image, though... It is actually done using GLSL shaders through the LWJGL libraries.
I still need to benchmark it, but performance is way better. I might even get an animated gif once I figure how to avoid making them so heavy.
On other news, I've gone through all the archives and renamed the project from DooM-4K to miniDooM, as well as doing some typo hunting.
I'd better stick to that project name, lest I have to do the whole renaming thing again.