The picture I have on my screen is about 1 meg, & looks pretty good. Looks nice & sharp unless you put your face right up against the screen. My partner on skis, with a clear blue sky & a mountaintop behind her - beautiful day, about -10C IIRC.20mg is a large photo Ozzy. If you are still having trouble you could reduce the dimensions to about 1350 x 950 which should make each photo less than 1mg. That will still provide a picture that will fill a monitor screen when it is enlarged and be of good quality.
Cheers.