To get better (and more than 256) color palates, you have to do all the converting yourself in the code, you make a list of colors available with the type of particle and any life/temp values they need, and go through comparing your current picture pixel to each finding the palate color with least difference. You can also add dithering, just google on how to do that.

currently there are about 70 thousand element colors (haven't counted/checked in a while, it may be much higher)