Photos not always becoming sharp - urgent

[flamenco45]

I have a set of photos, all of which have displayed properly. When I ask iPad to show them in a sideshow, some appear blurred then become sharp. Others appear blurred and remain blurred even though they have been on display sharp previously. There is some urgency as I was hoping to show the slide show at my fathers funeral this Thursday. Should I resize the pictures or what? I really want a smooth, error free sideshow. Please help if you can.
Dave