You just have to make this picture brievely appears (like 1 second or less) with a monstruous sound.
You could make a layer especially made for Jumpscare. It's on this layer that you'll make the concerned picture visible. As you may understand, this Jumpscare layer has to be placed before the others layers (otherwise it will be a sort of "background" and your picture will spawn behind the decor, for example). Then there are plenty of options.
You could, for instance, place an invisible Sprite exactly where you want to trigger your jumpscare. When the player overlaps this invisible sprite, boum, the picture spawn with a horrible sound, and it's immediately destroyed after 1 second or less. Should be enough to do the trick.