[Unwise]

I had a similar problem when putzing around with my first map. I solved it thus:

If you're using photoshop, use the color/hue option to slightly darken all the layers except for the one containing your dots (if you don't have a layer just for the dots, make one).

The theory is that there are several white pixels very close to one another that is confusing the routine. By darkening the "eye candy" layers an infintesimal amount, you disqualify these from consideration.