Doom - resolution and image quality

[spud11]

Pi Model or other hardware: See signature
Power Supply used: standard + 2 powered hubs
RetroPie Version Used: See signature
Built From: Pre made SD Image on RetroPie website
USB Devices connected: See Signature
Controller used: See Signature
Error messages received: As per log shown below
Guide used: Retropie Docs/wiki for Doom
File:
Emulator: Zdoom
Attachment of config files:
How to replicate the problem: How to improve image quality at 1920x1080 resolution

I've been using Zdoom and have set the game to 1920x1080 for Brutal Doom and Project Brutality. I'm not really expecting the same image quality as on my PC where I'm using gzdoom and the engine is OpenGl and I've got an Nvidia 970, but I was hoping there might be suggestions as to how to get the best image quality on the Pi (eg anisotropic filtering??) without sacrificing too much in the way of speed. Any suggestions would be welcome, particularly if they are for the commandline.

I'm currently using individual bash scripts. An example config that I have:

 #!/bin/bash
/opt/retropie/ports/zdoom/zdoom -width 1920 -height 1080 +set fullscreen 1 +set freelook 0 -config /opt/retropie/configs/ports/doom/zdoom.ini -iwad /home/pi/RetroPie/roms/ports/doom/doom2.wad -file /home/pi/RetroPie/roms/ports/doom/brutalv20b.pk3 -file /home/pi/RetroPie/roms/ports/doom/mapsofchaos-ok.wad -file /home/pi/RetroPie/roms/ports/doom/DoomHDv03.pk3 -file /home/pi/RetroPie/roms/ports/doom/zdoom-dhtp-20130802.pk3 -file /home/pi/RetroPie/roms/ports/doom/brightmaps.pk3 -file /home/pi/RetroPie/roms/ports/doom/lights.pk3 -file /home/pi/RetroPie/roms/ports/doom/BrutalTeam_Metal.wad

Thanks.