Image fusion is a way of combining two or more pictures into one. The idea is that by combining the pictures, you can get a better idea of what the scene or object looks like overall. For example, if you are taking a picture of a person and they are wearing glasses, you can use image fusion to combine a picture of their face with a picture of their glasses. This way, you don't miss out on the detail of their glasses and still get a good overall picture of the person.