Images seem to look the same in Aurora 18.0a2 as they did in FF 17.0.
FF: http://puu.sh/1vYCv Aurora: http://puu.sh/1vYzU
And my image scaling options in Aurora are: http://puu.sh/1vYR2
I tried the min factor at default, and at 1, same result. I don't care about performance, I want to see high quality rendering always.