EDIT: I should mention I'm running Ubuntu 12.04 with Cinnamon, though I could switch to Unity to change, then switch back.
Alright, so I changed the background on my login screen (the cheap way, by just renaming my image to "/usr/share/backgrounds/warty-final-ubuntu.png"), and the color of the ubuntu loading splash (by editing /lib/plymouth/themes/ubuntu-logo/ubuntu-logo.script). These both work perfectly fine.
The problem: Between the loading splash and the login screen, there's a brief period while my background image loads, where the background is just the default purple color, with the white dot overlay. I'd like to know how I can change the color of this (and possibly get rid of the dots too).