In Prezi Classic there was the option to add multiple backgrounds into your presentation. You could zoom in and a different background was revealed depending on the level of zoom. You can also achieve a similar effect in Prezi Next. Watch the example below with a bowling ball and pins:
Prezi Classic supported up to 3 backgrounds, but in Prezi Next you can only use 2 background: one that will be visible in the overview slide and the second that will be revealed when you zoom into a topic. The trick here is that you add one background as the Real background image from the background menu. The second image is just a regular image that you insert into your overview slide (Use right click and “send to back” to send it behind all other content). The peculiarity of Prezi Next is that while your are on the overview slide then all content is visible, however when you zoom into a topic, then all other content, except the “real background” image will disappear.
With this simple trick you can easily achieve the effect of one background image changing a little or completely turning into a another image. The most common use of this effect would be to make the same background image blurred once you zoom in.