Indexed Colour

What would be a »good result«? 

What annoys you the most – the dithering, …? 

As @Trevor.Dennis already indicated please post screenshots so others might better understand what you are talking about. 

Can you maybe tell us a bit more about what you are trying to do?

Is there a reason you are using Indexed Color? 

Are doing something like designing sprites for an old school game look maybe?

Could you do this in RGB mode and then drop down to Indexed?

How many colours (bit depth) are you using?

Screen shots might help.

I'm thinking that if we knew your ultimate end state, then we might have other ideas on how to get there.

Yesh, Same issue