ok but if this is the case, I think this is not a good behavior.
because If you define 4 images per slide for example and If you have only 6 images, then bullets will not be displayed.
I think a user friendly behavior is to diplay bullets everytime your images number is higher than limit defined.
ex 1: you define 4 images per slide for example and you upload 3 images => bullets are not displayed.
ex 2: you define 4 images per slide for example and you upload 5 images or more => bullets are displayed.
this is more logic I think.