make sure the image you use has exact pixel dimensions meaning it should be like 50x50 and not 50.2x50.4pixels. next make sure the x and y coordinates of the image in flash is set to exact pixels. next break apart the image ang group it. If you placed it inside a movie clip make the registration pint at 0,0 and set its alpha to 97%. if your image hase a border make it 1px or any thickness as long as it is an exact pixel.
This is the thing I do to my image in flash to make them appear decent at least.