>>1076517I find Paint Tool Sai is excellent for this. Does not just provide a generic Quality slider but fine tuning options like color fidelity. Also ignore the weird symbols instead of text, seems to be a side effect of me running it under wine on linux.
It can easily aquired at, ahem, 100% discount on the internet.
Also of course Photoshop, especially if wanna try some tricks like pallette change (Indexed color etc).
