When you project a photo or other image during a public speaking engagement, fill up the slide, or overhead as much as possible. This does not mean to fill the projection with lots of text. This tip only applies to images. Example: You take a picture of a funny sign on a pole. The sign is only about 18 inches tall. If you zoom in on the sign so that it fills the frame, it will have a much greater impact on the audience.
In the sample below the same piece of clip art has a completely different impact and effect because it fills the frame. When speaking in public, don't forget the impact of your visuals.