possibility to change an image each time an application opens

thank you for helping me find a solution:

is there a possibility to change an image each time an application opens ???

I made this code

<img style = "position: relative; margin-left: 0; zoom: 100%; height: 100%" src = "images / home <? php $ random = rand (1,4); echo $ random;?> .png "alt =" [Random Image] "/>

but each image does not always change at each opening of the application sometimes it changes by another image sometimes not.