The button object in Max gives visual feedback when it’s clicked upon, by flashing once briefly. If you’re using a picture (an fpic object) to serve as a button and you’d like it to give that same sort of visual feedback when clicked, you can cover the fpic object with a ubutton object, which behaves rather like a button but becomes transparent when the patch is locked.

Set up a flashing picture using ubutton

This is what it will look like in Presentation Mode.

The picture flashes when clicked.