The transparency of the image can be adjusted from invisible to completely visible.
The picture is a layer on top of the screen and all other apps under the layer are still clickable.
So it is possible, to take a new picture with the camera, which is similar to the old picture or rather only one object changes and the remaining parts are the same.
Of course, just a resized image can be placed anywhere on the screen and is always shown. To prevent that the toolbar takes place from screen, it can be hidden.