I tried this with self service counter in our Tesco store. With hand scanner it worked, those built in the table did not want to read the code from watch display. It should make it simpler for me to access the bonus cards for different stores. But the principle can be applied even on other images.
I will simply attach link to an example how can be the custom variables pro feature used to display multiple different images temporary or on toggle. We had these in some topic I do not remember, so I tried to summarize two approaches in one face. Sorry, I am not going to extract the formulas here. I assume who had the urge to subscribe for pro, has at least minimal knowledge how to inspect open faces. To access it, right click the face and open it in new browser tab or window.
The upper button toggles and cycles trough the images with just repeating touch in same spot, then the image disappears after 5 seconds.
The bottom has the feature splitted, one var is used to turn the image on/off, other var is used to cycle trough them.